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+I n t e r n a t i o n a l   T e l e c o m m u n i c a t i o n   U n i o n
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**X.1032**
+
+(12/2010)
+
+SERIES X: DATA NETWORKS, OPEN SYSTEM  
+COMMUNICATIONS AND SECURITY
+
+Information and network security – Network security
+
+# --- **Architecture of external interrelationships for a telecommunication IP-based network security system**
+
+Recommendation ITU-T X.1032
+
+![ITU-T logo](84a1d09fb489061482111515543b60dc_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with a red lightning bolt striking it, and the text "ITU" in blue, followed by "International Telecommunication Union" in a smaller font.
+
+ITU-T logo
+
+## ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY
+
+|                                    |                      |
+|------------------------------------|----------------------|
+| PUBLIC DATA NETWORKS               | X.1–X.199            |
+| OPEN SYSTEMS INTERCONNECTION       | X.200–X.299          |
+| INTERWORKING BETWEEN NETWORKS      | X.300–X.399          |
+| MESSAGE HANDLING SYSTEMS           | X.400–X.499          |
+| DIRECTORY                          | X.500–X.599          |
+| OSI NETWORKING AND SYSTEM ASPECTS  | X.600–X.699          |
+| OSI MANAGEMENT                     | X.700–X.799          |
+| SECURITY                           | X.800–X.849          |
+| OSI APPLICATIONS                   | X.850–X.899          |
+| OPEN DISTRIBUTED PROCESSING        | X.900–X.999          |
+| INFORMATION AND NETWORK SECURITY   |                      |
+| General security aspects           | X.1000–X.1029        |
+| <b>Network security</b>            | <b>X.1030–X.1049</b> |
+| Security management                | X.1050–X.1069        |
+| Telebiometrics                     | X.1080–X.1099        |
+| SECURE APPLICATIONS AND SERVICES   |                      |
+| Multicast security                 | X.1100–X.1109        |
+| Home network security              | X.1110–X.1119        |
+| Mobile security                    | X.1120–X.1139        |
+| Web security                       | X.1140–X.1149        |
+| Security protocols                 | X.1150–X.1159        |
+| Peer-to-peer security              | X.1160–X.1169        |
+| Networked ID security              | X.1170–X.1179        |
+| IPTV security                      | X.1180–X.1199        |
+| CYBERSPACE SECURITY                |                      |
+| Cybersecurity                      | X.1200–X.1229        |
+| Countering spam                    | X.1230–X.1249        |
+| Identity management                | X.1250–X.1279        |
+| SECURE APPLICATIONS AND SERVICES   |                      |
+| Emergency communications           | X.1300–X.1309        |
+| Ubiquitous sensor network security | X.1310–X.1339        |
+| CYBERSECURITY INFORMATION EXCHANGE |                      |
+| Cyber information exchange         | X.1500–X.1519        |
+| Vulnerability/state exchange       | X.1520–X.1539        |
+| Event/incident/heuristics exchange | X.1540–X.1549        |
+| Exchange of policies               | X.1550–X.1559        |
+| Heuristics and information request | X.1560–X.1569        |
+| Identification and discovery       | X.1570–X.1579        |
+| Assured exchange                   | X.1580–X.1589        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+## **Recommendation ITU-T X.1032**
+
+# **Architecture of external interrelationships for a telecommunication IP-based network security system**
+
+## **Summary**
+
+Recommendation ITU-T X.1032 proposes four models that make possible a review of interrelationships between a telecommunication IP-based network security system (TNSS) and various groups of external objects. Each object is considered in terms of its main functions and its probable effect on TNSS construction and functioning principles. This Recommendation provides a basis for developing detailed recommendations on network security with regard to the effect on external objects.
+
+## **History**
+
+| Edition | Recommendation | Approval   | Study Group |
+|---------|----------------|------------|-------------|
+| 1.0     | ITU-T X.1032   | 2010-12-17 | 17          |
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2011
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|    |                                                                                                              | <b>Page</b> |
+|----|--------------------------------------------------------------------------------------------------------------|-------------|
+| 1  | Scope .....                                                                                                  | 1           |
+| 2  | References.....                                                                                              | 2           |
+| 3  | Definitions .....                                                                                            | 2           |
+|    | 3.1 Terms defined elsewhere.....                                                                             | 2           |
+|    | 3.2 Terms defined in this Recommendation.....                                                                | 2           |
+| 4  | Abbreviations and acronyms .....                                                                             | 3           |
+| 5  | Conventions .....                                                                                            | 3           |
+| 6  | General.....                                                                                                 | 3           |
+| 7  | TNSS interrelationships with security systems of information systems and<br>information structure .....      | 3           |
+|    | 7.1 Model of interrelationships.....                                                                         | 3           |
+|    | 7.2 Functions of external objects and their effect on TNSS.....                                              | 3           |
+| 8  | TNSS interrelationships with telecommunication system objects.....                                           | 5           |
+|    | 8.1 Model of TNSS interrelationships.....                                                                    | 5           |
+|    | 8.2 Functions of external objects and their effect on TNSS.....                                              | 5           |
+| 9  | TNSS interrelationships with external organizations .....                                                    | 6           |
+|    | 9.1 Model of interrelationships.....                                                                         | 6           |
+|    | 9.2 Functions of external organizations and their effect on TNSS.....                                        | 6           |
+| 10 | TNSS interrelationships with security threats sources .....                                                  | 7           |
+|    | 10.1 Model of interrelationships.....                                                                        | 7           |
+|    | 10.2 Functions of external objects and their effect on TNSS.....                                             | 7           |
+|    | Appendix I – Possible composition of technical facilities of the telecommunication<br>IP-based network ..... | 9           |
+|    | Bibliography.....                                                                                            | 10          |
+
+
+
+# Architecture of external interrelationships for a telecommunication IP-based network security system
+
+# 1 Scope
+
+**1.1** A study of any object needs to take into account not only the interconnections between different components within the object, but also the object's external relationships. Through external relationships, the object performs its functions in the context of an overall system. However, these interrelationships may pose a risk due to a variety of threats that can disturb the functioning of the object.
+
+A study of these objects is particularly important for a telecommunication IP-based network security system (TNSS), which needs to protect a telecommunication IP-based network mainly against external threats (see Figure 1).
+
+Possible composition of technical components of a telecommunication IP-based network is presented in Appendix I.
+
+![Diagram illustrating the interrelationships between a telecommunication IP-based network and its security system (TNSS).](0236eff05bcb8f3a343ea7933aaa306b_img.jpg)
+
+The diagram shows a large blue rectangle labeled "Telecommunication IP-based network". Inside this rectangle, at the bottom, is a smaller pink rectangle labeled "Telecommunication IP-based network security system (TNSS)". Below the pink rectangle, there is a dashed horizontal line. Three white circles are positioned on this dashed line. From each circle, a white arrow points upwards towards the bottom edge of the pink rectangle. Below the dashed line, the text "Interrelationships with external objects and external threats in a telecommunication IP-based network" is centered. To the right of the dashed line, the text "TNSS external interfaces/ interrelations points" is written. At the bottom right of the diagram, the identifier "X.1032(10)\_F01" is present.
+
+Diagram illustrating the interrelationships between a telecommunication IP-based network and its security system (TNSS).
+
+**Figure 1 – Interrelationships between a telecommunication IP-based network security system and external objects**
+
+**1.2** The TNSS does not function as a free-running system; it works in close interaction with a number of external systems.
+
+Firstly, these external systems include the telecommunication IP-based network itself, which protects the TNSS. The principles that govern the construction of the transport medium and the service platforms directly determine the requirements and, therefore, the design of the TNSS.
+
+Secondly, these external systems include the telecommunication IP-based network users whose requirements should be fulfilled by the telecommunication IP-based network and its TNSS.
+
+Some other external organizations can also affect the TNSS construction principles. These organizations include:
+
+- national regulatory authorities;
+- trusted third parties providing services for security systems (on the "outsourcing" principle);
+- organizations using telecommunication IP-based network services for the creation of information networks.
+
+In essence, the main TNSS tasks consist of the protection of the telecommunication IP-based network and the information transmitted through this network against the various external security threats in the environment in which the TNSS functions.
+
+The above list indicates that TNSS has interrelationships with many external objects which may be subdivided into several groups.
+
+**1.3** TNSS interrelationships with external objects can either directly or indirectly affect the TNSS requirements, the TNSS construction and the functioning principles. Therefore, these interrelationships should be taken into account in the course of TNSS development. Existing ITU-T Recommendations address certain aspects of this problem (for example, [ITU-T X.842] and [ITU-T X.843] address interrelationships with a trusted third party). However, there are many aspects of TNSS interrelationships with external objects that have not yet been considered.
+
+**1.4** This Recommendation covers a general architecture of TNSS interrelationships with external objects. This architecture can be applied to various types of telecommunication IP-based networks and to various telecommunication security systems. This Recommendation provides an overview of all external interrelationships of TNSS. This Recommendation may serve as a basis for elaborating more detailed recommendations on network security, with respect to the effect on external objects.
+
+# **2 References**
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T X.800] Recommendation ITU-T X.800 (1991), *Security architecture for Open Systems Interconnection for CCITT applications*.
+
+[ITU-T X.805] Recommendation ITU-T X.805 (2003), *Security architecture for systems providing end-to-end communications*.
+
+[ITU-T X.842] Recommendation ITU-T X.842 (2000) | ISO/IEC TR14516:2002, *Information technology – Security techniques – Guidelines for the use and management of trusted third party services*.
+
+[ITU-T X.843] Recommendation ITU-T X.843 (2000) | ISO/IEC 15945:2002, *Information technology – Security techniques – Specification of TTP services to support the application of digital signatures*.
+
+# **3 Definitions**
+
+## **3.1 Terms defined elsewhere**
+
+None.
+
+## **3.2 Terms defined in this Recommendation**
+
+This Recommendation defines the following terms:
+
+**3.2.1 security system:** A variety of interrelating elements (certain principles, organization and technical measures for security provision) that minimize vulnerability of assets and resources.
+
+**3.2.2 telecommunication IP-based network security system (TNSS):** Security system used in a telecommunication IP-based network.
+
+# **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+ICT Information and Communication Technologies
+
+TNSS Telecommunication IP-based Network Security System
+
+# **5 Conventions**
+
+None.
+
+# **6 General**
+
+**6.1** Consideration of TNSS interrelationships with external objects is complicated by the great number of these objects and by various types of relationships and interfaces. Therefore, a major problem is the possibility of decomposition (division) of the set of interrelationships. This Recommendation proposes four types of external interrelationships:
+
+- TNSS interrelationships with security systems that overlay infrastructure information systems and information structures;
+- TNSS interrelationships with telecommunication system objects;
+- TNSS interrelationships with other objects, e.g., external organizations;
+- TNSS interrelationships with security threats in the form of either the above-named objects or new objects.
+
+These types of interrelationships are considered below in clauses 7, 8, 9 and 10, respectively.
+
+**6.2** In addition, each of the clauses 7, 8, 9 and 10 employs the decomposition principle. First, a model of interrelationships is defined in a graphical form. This model contains external objects and their interrelationships with TNSS. The functions of each external object are then described. Finally, proceeding from these functions, brief assessments are made for:
+
+- the possible effects of external objects on TNSS (for example, effects on requirements to TNSS, effects on principles of TNSS construction and functioning);
+- the possible types of interrelationship (for example, an electrical interface, organizational requirements, external environment influences).
+
+# **7 TNSS interrelationships with security systems of information systems and information structure**
+
+## **7.1 Model of interrelationships**
+
+Figure 2 shows TNSS interrelationships with security systems that overlay infrastructure information systems which, in turn, have interfaces with information structure security systems.
+
+## **7.2 Functions of external objects and their effect on TNSS**
+
+**7.2.1** Information systems employ various kinds of information technologies using telecommunications. Functions of information systems include, for instance, collection, storage and retrieval of information, organization of databases and users' sites, technical support of editing, conversion and other kinds of information processing. Information systems can perform functions of remote information transfer and distribution, using telecommunication services (i.e., from
+
+information-telecommunication networks). Internet is one example of a public information-telecommunication network.
+
+Traditional types of communication (for example, telephone communication and facsimile communication) can be effected both with and without the use of information-telecommunication network.
+
+Information system security systems serve to protect the technical processes of these systems and the information stored and transferred within these systems. Information system security systems may affect TNSS in the following way, for example:
+
+- supplement each other during protection against certain threats, for instance, against information disclosure; and
+- introduce limitations for security protocols used within TNSS.
+
+External interrelationships of TNSS with the information system security systems may be:
+
+- hardware or software interfaces; or
+- contractual agreements.
+
+![Figure 2: Model of TNSS interrelationships with security systems of information systems and information structure. The diagram shows three stacked layers. The top layer, 'Information structure', contains 'Users (people and machinery – sources and recipients of information) + connecting cyberspace + information circulation in cyberspace' and an 'Information structure security system'. The middle layer, 'Information-telecommunication infrastructure', contains 'Information systems' and 'Information system security systems'. The bottom layer, 'Telecommunication IP-based network', contains a 'Telecommunication IP-based network security system (TNSS)'. Vertical double-headed arrows connect the security systems across the layers: between the top and middle layers, and between the middle and bottom layers. A long vertical double-headed arrow also connects the top and bottom layers. Labels on the left indicate the vertical extent of each layer: 'Information structure' for the top, 'Information-telecommunication infrastructure' for the middle, and 'Telecommunication IP-based network' for the bottom. A small identifier 'X.1032(10)_F02' is at the bottom right of the diagram.](053f1077d592e6622cd21dc4bb4cb366_img.jpg)
+
+Figure 2: Model of TNSS interrelationships with security systems of information systems and information structure. The diagram shows three stacked layers. The top layer, 'Information structure', contains 'Users (people and machinery – sources and recipients of information) + connecting cyberspace + information circulation in cyberspace' and an 'Information structure security system'. The middle layer, 'Information-telecommunication infrastructure', contains 'Information systems' and 'Information system security systems'. The bottom layer, 'Telecommunication IP-based network', contains a 'Telecommunication IP-based network security system (TNSS)'. Vertical double-headed arrows connect the security systems across the layers: between the top and middle layers, and between the middle and bottom layers. A long vertical double-headed arrow also connects the top and bottom layers. Labels on the left indicate the vertical extent of each layer: 'Information structure' for the top, 'Information-telecommunication infrastructure' for the middle, and 'Telecommunication IP-based network' for the bottom. A small identifier 'X.1032(10)\_F02' is at the bottom right of the diagram.
+
+**Figure 2 – Model of TNSS interrelationships with security systems of information systems and information structure**
+
+**7.2.2** Information structure ensures information is used in all spheres of human activities. The information structure security system serves to protect users of cyberspace (authors, owners, sources, recipients and buyers of information) against intrusions in cyberspace which disrupt the users' work. Cyberspace users include both people and machinery (sensing elements, actuators, automatics, etc.). Examples of unwanted intrusions are viruses, "worms", spam and various malware that exist in cyberspace. An unwanted intrusion may also include a denial of service in the information and communication infrastructure.
+
+The information structure security system may affect TNSS directly or via information network security systems. For example, it may place requirements on TNSS such as cyberspace protection by means of technical tools which could support the implementation of legal, administrative and organizational measures used within the information structure security system. Such technical tools include the means to counter viruses and spam.
+
+The external interrelationship of TNSS with the information structure security system may be by a contractual agreement.
+
+# 8 TNSS interrelationships with telecommunication system objects
+
+## 8.1 Model of TNSS interrelationships
+
+Figure 3 shows TNSS interrelationships with its own telecommunication network objects and with security systems of other telecommunication system objects, i.e., with security systems of users' terminal equipment and neighbouring telecommunication networks.
+
+## 8.2 Functions of external objects and their effect on TNSS
+
+**8.2.1** Telecommunication network internal objects (transport stratum and service stratum) determine the nomenclature of provided telecommunication services, as well as quantitative and qualitative characteristics of these services. These objects directly affect TNSS. In particular, they determine:
+
+- The list of services subject to protection;
+- The network possibilities for the realization of security mechanisms.
+
+External interrelationships of TNSS with the transport stratum and the service stratum may be:
+
+- hardware or software interfaces; or
+- contractual agreements.
+
+![Figure 3: Model of TNSS interrelationships with telecommunication system objects. The diagram illustrates the interactions between the Telecommunication IP-based network security system (TNSS) and its external components. The central element is the 'Telecommunication IP-based network' (blue box), which contains the 'Transport stratum' and 'Service stratum' (light blue boxes). Below this is the 'Telecommunication IP-based network security system (TNSS)' (red box). To the left, a green box represents 'Neighbouring telecommunication networks (including networks in other countries)', which contains a purple box for 'Security systems of neighbouring telecommunication networks'. To the right, a green box represents 'User terminal systems', which contains a purple box for 'Security systems of users' terminal systems'. Above the left green box is another green box for 'Users of information-telecommunication networks', and above the right green box is a green box for 'Users of information-telecommunication networks (people and machinery – sources and recipients of information)'. Double-headed arrows indicate bidirectional relationships between the TNSS and the security systems of neighbouring networks and users' terminal systems. Additionally, double-headed arrows connect the users to their respective terminal systems, and the terminal systems to the neighbouring networks.](c78c2eefd86269d1740ab85a916f24f2_img.jpg)
+
+Figure 3: Model of TNSS interrelationships with telecommunication system objects. The diagram illustrates the interactions between the Telecommunication IP-based network security system (TNSS) and its external components. The central element is the 'Telecommunication IP-based network' (blue box), which contains the 'Transport stratum' and 'Service stratum' (light blue boxes). Below this is the 'Telecommunication IP-based network security system (TNSS)' (red box). To the left, a green box represents 'Neighbouring telecommunication networks (including networks in other countries)', which contains a purple box for 'Security systems of neighbouring telecommunication networks'. To the right, a green box represents 'User terminal systems', which contains a purple box for 'Security systems of users' terminal systems'. Above the left green box is another green box for 'Users of information-telecommunication networks', and above the right green box is a green box for 'Users of information-telecommunication networks (people and machinery – sources and recipients of information)'. Double-headed arrows indicate bidirectional relationships between the TNSS and the security systems of neighbouring networks and users' terminal systems. Additionally, double-headed arrows connect the users to their respective terminal systems, and the terminal systems to the neighbouring networks.
+
+**Figure 3 – Model of TNSS interrelationships with telecommunication system objects**
+
+**8.2.2** Users' terminal systems may contain some terminal devices (telephone apparatus, television sets, computers and other sort of terminals) and relevant home/corporate network connections (see Appendix I for details). Security systems of users' terminal systems perform functions of protection for terminal devices and home/corporate networks against security threats. These threats may emanate either from the telecommunication network itself or from internal sources (e.g., users' terminal systems). Besides, security systems of users' terminal systems employ mechanisms to protect user information transmitted to the telecommunication network.
+
+Security systems of users' terminal systems may affect TNSS. In particular, they may:
+
+- support each other during protection of user information against certain threats, for example, by encrypting transmitted data;
+- determine requirements for the target security level(s) to be ensured by TNSS.
+
+External interrelationships of TNSS with the security systems of users' terminal systems may be:
+
+- an electrical interface; or
+- organizational requirements and limitations.
+
+**8.2.3** Neighbouring telecommunication networks (including networks in other countries) perform traffic exchange with the telecommunication network under consideration. Security systems of neighbouring telecommunication networks perform functions to protect these networks and the information transmitted via these networks against security threats. These systems may affect TNSS, in particular, they may:
+
+- supplement each other during users' information protection against certain threats, for example, against corruption or modification of information; and
+- introduce limitations for use of certain TNSS security mechanisms or functioning modes of these mechanisms.
+
+External interrelationships of TNSS with security systems of neighbouring telecommunication networks may be:
+
+- an electrical interface; or
+- agreed bilateral organizational provisions.
+
+# **9 TNSS interrelationships with external organizations**
+
+## **9.1 Model of interrelationships**
+
+Figure 4 shows TNSS interrelationships with various organizations external to the telecommunication network including:
+
+- regulatory authorities;
+- trusted third parties;
+- law-enforcement authorities; and
+- providers of technical tools (hardware and software).
+
+![Diagram illustrating the Model of TNSS interrelationships with external organizations. The central element is the 'Telecommunication IP-based network security system (TNSS)' (pink box), which is part of the 'Telecommunication IP-based network' (blue box). The TNSS interacts with several external entities: 'National regulatory authorities, laws, standards and regulations' (green box) above, 'International standards' (green box) to the right, 'Trusted third parties' (green box) to the left, 'Law-enforcement authorities (prosecution of malefactors)' (green box) to the right, and 'Providers of technical tools (hardware and software)' (green box) below. Arrows indicate bidirectional interactions between the TNSS and these entities.](78ffccd66df9bafd96e3e081110d09dd_img.jpg)
+
+```
+graph TD
+    NRA[National regulatory authorities, laws, standards and regulations] <--> IS[International standards]
+    NRA <--> TNSS[Telecommunication IP-based network security system (TNSS)]
+    IS <--> TNSS
+    TTP[Trusted third parties] <--> TNSS
+    LEA[Law-enforcement authorities (prosecution of malefactors)] <--> TNSS
+    PTT[Providers of technical tools (hardware and software)] --> TNSS
+```
+
+Diagram illustrating the Model of TNSS interrelationships with external organizations. The central element is the 'Telecommunication IP-based network security system (TNSS)' (pink box), which is part of the 'Telecommunication IP-based network' (blue box). The TNSS interacts with several external entities: 'National regulatory authorities, laws, standards and regulations' (green box) above, 'International standards' (green box) to the right, 'Trusted third parties' (green box) to the left, 'Law-enforcement authorities (prosecution of malefactors)' (green box) to the right, and 'Providers of technical tools (hardware and software)' (green box) below. Arrows indicate bidirectional interactions between the TNSS and these entities.
+
+X.1032(10)\_F04
+
+**Figure 4 – Model of TNSS interrelationships with external organizations**
+
+## **9.2 Functions of external organizations and their effect on TNSS**
+
+**9.2.1** Regulatory authorities define general policies in the telecommunication field. In particular, they support the development and application of international standards, regulations and laws, while also supporting the development of national standards.
+
+**9.2.2** In compliance with bilateral agreements with a telecommunication network operator, third parties may perform certain functions to ensure TNSS operation.
+
+The list of these functions and principles of interaction between third parties and TNSS are determined by the operator of the infrastructure which incorporates the given TNSS.
+
+External interrelationships of TNSS with third parties may be:
+
+- hardware or software interfaces; or
+- contractual agreements.
+
+**9.2.3** Law-enforcement authorities (prosecution of malefactors) should respond to national law violations related to the information and telecommunication network area. Specifically, they should catch malefactors responsible for such violations. The work of law-enforcement authorities and TNSS functioning supplement each other which enhances telecommunication security.
+
+Given the importance of information and communication technologies (ICT) in all spheres of human society, as we progress towards the information society, law development is and will remain essential. Eventually, this trend will enhance the role of the relevant law-enforcement authorities.
+
+To perform the aforesaid functions, law-enforcement authorities should receive timely data from telecommunication network operators on security incidents that constitute violations of the law. TNSS should perform acquisition, storage and analysis of information which would enable the corresponding messages to be compiled and sent to law-enforcement authorities. The possibility to transfer information on security incidents from telecommunication organizations to law enforcement authorities is indicated for example in [b-ITU-T E.409], [b-ITU-T X.1051] and [b-ITU-T X.1056].
+
+External interrelationships of TNSS with law-enforcement authorities may be:
+
+- electrical interface or other telecommunication services or postal services; and
+- organizational provisions agreed bilaterally.
+
+# **10 TNSS interrelationships with security threats sources**
+
+## **10.1 Model of interrelationships**
+
+Figure 5 shows a model of TNSS interrelationships with various security threat sources which include:
+
+- users and their terminal systems connected to the subject telecommunication network;
+- outsiders (non-users) and external media;
+- objects and personnel of the telecommunication network;
+- neighbouring telecommunication networks, including relevant users and users' terminal systems;
+- connected information systems;
+- trusted third parties; and
+- providers of technical tools.
+
+## **10.2 Functions of external objects and their effect on TNSS**
+
+Security threat sources may attack telecommunication networks. Telecommunication IP-based network security system (TNSS) is used to avert, detect and neutralize such attacks. Therefore, it is safe to say that security threats are directly related to TNSS as shown in Figure 5.
+
+![Figure 5: Model of TNSS interrelationships with security threat sources. The diagram shows a central 'Telecommunication IP-based network security system (TNSS)' (pink box) nested within a 'Telecommunication IP-based network' (blue box). The TNSS is connected via bidirectional arrows to various threat sources: 'Threats from users', 'Threats from user terminal systems', 'Threats from neighbouring telecommunication networks', 'Threats from trusted third parties', 'Threats from providers of technical tools', 'Threats from outsiders', and 'Threats from external medium'. Additionally, 'Threats from telecommunication network's objects and personnel' are shown within the network box, connected to the TNSS. A separate box at the top, 'Threats from information systems', is also connected to the network. The diagram is labeled X.1032(10)_F05.](4801720824e4b5e2361a5564f91cfb70_img.jpg)
+
+Figure 5: Model of TNSS interrelationships with security threat sources. The diagram shows a central 'Telecommunication IP-based network security system (TNSS)' (pink box) nested within a 'Telecommunication IP-based network' (blue box). The TNSS is connected via bidirectional arrows to various threat sources: 'Threats from users', 'Threats from user terminal systems', 'Threats from neighbouring telecommunication networks', 'Threats from trusted third parties', 'Threats from providers of technical tools', 'Threats from outsiders', and 'Threats from external medium'. Additionally, 'Threats from telecommunication network's objects and personnel' are shown within the network box, connected to the TNSS. A separate box at the top, 'Threats from information systems', is also connected to the network. The diagram is labeled X.1032(10)\_F05.
+
+**Figure 5 – Model of TNSS interrelationships with security threat sources**
+
+Threats are classified under five types as given in [ITU-T X.800] and [ITU-T X.805]:
+
+- destruction of information and other resources;
+- corruption or modification of information;
+- theft, removal or loss of information and other resources;
+- disclosure of information; and
+- interruption of services.
+
+Security policy in a telecommunication network may be used either to counteract all threats or to counteract some of these threats. Correspondingly, required security dimensions are selected in the course of TNSS elaboration. Mapping of security threats to security dimensions is given in Table 1 of [ITU-T X.805].
+
+External interrelationships of TNSS with security treat sources may be:
+
+- electrical interfaces;
+- actions of people;
+- attacks using technical means via the telecommunication network and external technical means;
+- external environmental influences;
+- technical measures for counteracting attacks; and
+- organizational measures for counteracting attacks.
+
+# **Appendix I**
+
+### **Possible composition of technical facilities of the telecommunication IP-based network**
+
+(This appendix does not form an integral part of this Recommendation)
+
+**I.1** This Recommendation uses the term "telecommunication network" to cover the following facilities of the telecommunication operators:
+
+- facilities of the infrastructure providers (i.e., network nodes, their connecting circuits, access networks, etc.);
+- facilities of the service providers (i.e., service servers, etc.); a role of the service provider can be played by the infrastructure provider; otherwise, the service provider may operate within the network independently;
+- facilities of the application providers (i.e., application servers, etc.); a role of the application provider can be played by the service provider; otherwise, the application provider may function within the network independently;
+- connection, connecting the user with the telecommunication operator (i.e., with the infrastructure/service/application provider); and
+- information being transferred and stored within the facilities run by the infrastructure/service/application providers.
+
+**I.2** The telecommunication network does not include the term "user terminal systems". Such systems contain:
+
+- a telecommunication subscriber terminal(s) (together with its software to perform the functions of an infrastructure user, a service user and an application user, including execution of certain local functions – for example, message preparation and editing);
+- an application server(s), if the user performs the functions of an application services provider external to the network structure;
+- a corporate/local/home network (if present);
+- a firewall/gateway (if present); and
+- user information – transmitted, received and stored.
+
+## Bibliography
+
+- [b-ITU-T E.409] Recommendation ITU-T E.409 (2004), *Incident organization and security incident handling: Guidelines for telecommunication organizations*.
+- [b-ITU-T X.1051] Recommendation ITU-T X.1051 (2008) | ISO/IEC 27011:2008, *Information technology – Security techniques – Information security management guidelines for telecommunications organizations based on ISO/IEC 27002*.
+- [b-ITU-T X.1056] Recommendation ITU-T X.1056 (2009), *Security incident management guidelines for telecommunications organizations*.
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                             |
+|-----------------|---------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                           |
+| Series D        | General tariff principles                                                                   |
+| Series E        | Overall network operation, telephone service, service operation and human factors           |
+| Series F        | Non-telephone telecommunication services                                                    |
+| Series G        | Transmission systems and media, digital systems and networks                                |
+| Series H        | Audiovisual and multimedia systems                                                          |
+| Series I        | Integrated services digital network                                                         |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals |
+| Series K        | Protection against interference                                                             |
+| Series L        | Construction, installation and protection of cables and other elements of outside plant     |
+| Series M        | Telecommunication management, including TMN and network maintenance                         |
+| Series N        | Maintenance: international sound programme and television transmission circuits             |
+| Series O        | Specifications of measuring equipment                                                       |
+| Series P        | Terminals and subjective and objective assessment methods                                   |
+| Series Q        | Switching and signalling                                                                    |
+| Series R        | Telegraph transmission                                                                      |
+| Series S        | Telegraph services terminal equipment                                                       |
+| Series T        | Terminals for telematic services                                                            |
+| Series U        | Telegraph switching                                                                         |
+| Series V        | Data communication over the telephone network                                               |
+| <b>Series X</b> | <b>Data networks, open system communications and security</b>                               |
+| Series Y        | Global information infrastructure, Internet protocol aspects and next-generation networks   |
+| Series Z        | Languages and general software aspects for telecommunication systems                        |

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+
+
+I n t e r n a t i o n a l   T e l e c o m m u n i c a t i o n   U n i o n
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**X.1038**
+
+(10/2016)
+
+SERIES X: DATA NETWORKS, OPEN SYSTEM  
+COMMUNICATIONS AND SECURITY
+
+Information and network security – Network security
+
+# --- **Security requirements and reference architecture for software-defined networking**
+
+Recommendation ITU-T X.1038
+
+ITU-T
+
+![ITU International Telecommunication Union logo](1d7527f4316cfe2d342b08d1653d1592_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue globe with a red lightning bolt striking it, and the text "ITU International Telecommunication Union" to its right.
+
+ITU International Telecommunication Union logo
+
+## ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY
+
+|                                                        |                      |
+|--------------------------------------------------------|----------------------|
+| PUBLIC DATA NETWORKS                                   | X.1–X.199            |
+| OPEN SYSTEMS INTERCONNECTION                           | X.200–X.299          |
+| INTERWORKING BETWEEN NETWORKS                          | X.300–X.399          |
+| MESSAGE HANDLING SYSTEMS                               | X.400–X.499          |
+| DIRECTORY                                              | X.500–X.599          |
+| OSI NETWORKING AND SYSTEM ASPECTS                      | X.600–X.699          |
+| OSI MANAGEMENT                                         | X.700–X.799          |
+| SECURITY                                               | X.800–X.849          |
+| OSI APPLICATIONS                                       | X.850–X.899          |
+| OPEN DISTRIBUTED PROCESSING                            | X.900–X.999          |
+| INFORMATION AND NETWORK SECURITY                       |                      |
+| General security aspects                               | X.1000–X.1029        |
+| <b>Network security</b>                                | <b>X.1030–X.1049</b> |
+| Security management                                    | X.1050–X.1069        |
+| Telebiometrics                                         | X.1080–X.1099        |
+| SECURE APPLICATIONS AND SERVICES                       |                      |
+| Multicast security                                     | X.1100–X.1109        |
+| Home network security                                  | X.1110–X.1119        |
+| Mobile security                                        | X.1120–X.1139        |
+| Web security                                           | X.1140–X.1149        |
+| Security protocols                                     | X.1150–X.1159        |
+| Peer-to-peer security                                  | X.1160–X.1169        |
+| Networked ID security                                  | X.1170–X.1179        |
+| IPTV security                                          | X.1180–X.1199        |
+| CYBERSPACE SECURITY                                    |                      |
+| Cybersecurity                                          | X.1200–X.1229        |
+| Countering spam                                        | X.1230–X.1249        |
+| Identity management                                    | X.1250–X.1279        |
+| SECURE APPLICATIONS AND SERVICES                       |                      |
+| Emergency communications                               | X.1300–X.1309        |
+| Ubiquitous sensor network security                     | X.1310–X.1339        |
+| PKI related Recommendations                            | X.1340–X.1349        |
+| CYBERSECURITY INFORMATION EXCHANGE                     |                      |
+| Overview of cybersecurity                              | X.1500–X.1519        |
+| Vulnerability/state exchange                           | X.1520–X.1539        |
+| Event/incident/heuristics exchange                     | X.1540–X.1549        |
+| Exchange of policies                                   | X.1550–X.1559        |
+| Heuristics and information request                     | X.1560–X.1569        |
+| Identification and discovery                           | X.1570–X.1579        |
+| Assured exchange                                       | X.1580–X.1589        |
+| CLOUD COMPUTING SECURITY                               |                      |
+| Overview of cloud computing security                   | X.1600–X.1601        |
+| Cloud computing security design                        | X.1602–X.1639        |
+| Cloud computing security best practices and guidelines | X.1640–X.1659        |
+| Cloud computing security implementation                | X.1660–X.1679        |
+| Other cloud computing security                         | X.1680–X.1699        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T X.1038
+
+# Security requirements and reference architecture for software-defined networking
+
+## Summary
+
+Recommendation ITU-T X.1038 supports security protection and provides security requirements and a reference architecture for software-defined networking (SDN). This Recommendation identifies new security threats as well as traditional network security threats to SDN, defines security requirements, provides possible security countermeasures against new security threats, and designs a security reference architecture for SDN.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T X.1038   | 2016-10-14 | 17          | <a href="http://handle.itu.int/11.1002/1000/13058">11.1002/1000/13058</a> |
+
+## Keywords
+
+SDN security, security reference architecture, security requirement, security threat.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2017
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|   |                                                                                          | Page |
+|---|------------------------------------------------------------------------------------------|------|
+| 1 | Scope.....                                                                               | 1    |
+| 2 | References.....                                                                          | 1    |
+| 3 | Definitions .....                                                                        | 2    |
+|   | 3.1 Terms defined elsewhere.....                                                         | 2    |
+|   | 3.2 Terms defined in this Recommendation.....                                            | 2    |
+| 4 | Abbreviations and acronyms .....                                                         | 3    |
+| 5 | Conventions .....                                                                        | 3    |
+| 6 | Overview.....                                                                            | 4    |
+| 7 | Security threats and requirements.....                                                   | 4    |
+|   | 7.1 SDN application layer .....                                                          | 4    |
+|   | 7.2 SDN control layer.....                                                               | 5    |
+|   | 7.3 SDN resource layer.....                                                              | 8    |
+|   | 7.4 Application-control interface.....                                                   | 9    |
+|   | 7.5 Resource-control interface.....                                                      | 10   |
+| 8 | Security reference architecture for SDN.....                                             | 11   |
+|   | 8.1 SDN application layer .....                                                          | 11   |
+|   | 8.2 SDN control layer.....                                                               | 13   |
+|   | 8.3 SDN resource layer.....                                                              | 16   |
+|   | 8.4 Multi-layer security management.....                                                 | 17   |
+|   | Annex A – Use cases of new security threats to SDN .....                                 | 19   |
+|   | A.1 Use case 1: Bypassing a predefined mandatory policy .....                            | 19   |
+|   | A.2 Use case 2: Data eavesdropping attacks by inserting fraudulent flow<br>entries ..... | 20   |
+|   | Annex B – Fine-grained naming scheme for flow entry.....                                 | 22   |
+|   | B.1 Fine-grained naming scheme for flow entry .....                                      | 22   |
+|   | Bibliography.....                                                                        | 23   |
+
+# **Introduction**
+
+Generally, security threats to SDN are common to other targets and to traditional networking, but the profile of the threats (including their likelihood and impact and hence their overall risk level) changes with the new SDN architecture. With a centralized SDN controller, the impact of a denial-of-service (DoS)/distributed denial-of-service (DDoS) attack can be higher than that directed against a single router. Some new functional entities (e.g., SDN controller), protocols (e.g., ONF OpenFlow) and interfaces (e.g., application-control interface, resource-control interface) according to the framework of SDN [ITU-T Y.3300] will pose new security threats. All these security threats must be understood and addressed.
+
+This Recommendation describes use cases to detail new security threats when introducing SDN. This Recommendation identifies security threats for the SDN application layer, SDN control layer, SDN resource layer, application-control interface, and resource-control interface according to the framework of SDN [ITU-T Y.3300]. This Recommendation also defines security requirements from above security threats analysis and studies possible security countermeasures against new security threats. With this information, a security reference architecture for SDN is designed based on the identified security threats, and security requirements and security countermeasures are specified. This security reference architecture can guide the developer to design a SDN security functional architecture and implement security functions when developing an SDN controller.
+
+# Recommendation ITU-T X.1038
+
+# Security requirements and reference architecture for software-defined networking
+
+# 1 Scope
+
+This Recommendation is to support security protection and to provide security requirements and a reference architecture for software-defined networking (SDN). This Recommendation:
+
+- describes use cases to detail new security threats when introducing SDN;
+- identifies major security threats to SDN;
+- defines security requirements;
+- provides possible security countermeasures against new security threats;
+- designs a security reference architecture for SDN.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [ITU-T X.800] Recommendation ITU-T X.800 (1991), *Security architecture for Open Systems Interconnection for CCITT applications*.
+- [ITU-T Y.3300] Recommendation ITU-T Y.3300 (2014), *Framework of software-defined networking*.
+- [IETF RFC 4210] IETF RFC 4210 (2005), *Internet X.509 Public Key Infrastructure Certificate Management Protocol (CMP)*.
+- [IETF RFC 4279] IETF RFC 4279 (2005), *Pre-Shared Key Ciphersuites for Transport Layer Security (TLS)*.
+- [IETF RFC 4301] IETF RFC 4301 (2005), *Security Architecture for the Internet Protocol*.
+- [IETF RFC 4303] IETF RFC 4303 (2005), *IP Encapsulating Security Payload (ESP)*.
+- [IETF RFC 4306] IETF RFC 4306 (2005), *Internet Key Exchange (IKEv2) Protocol*.
+- [IETF RFC 4314] IETF RFC 4314 (2005), *IMAP4 Access Control List (ACL) Extension*.
+- [IETF RFC 4835] IETF RFC 4835 (2007), *Cryptographic Algorithm Implementation Requirements for Encapsulating Security Payload (ESP) and Authentication Header (AH)*.
+- [IETF RFC 5246] IETF RFC 5246 (2008), *The Transport Layer Security (TLS) Protocol Version 1.2*.
+- [NIST 3DES] National Institute of Standards and Technology (2012), *Recommendation for the Triple Data Encryption Algorithm (TDEA) Block Cipher* (Revision 1), NIST Special Publication 800-67, January.
+
+|            |                                                                                                                                                    |
+|------------|----------------------------------------------------------------------------------------------------------------------------------------------------|
+| [NIST AES] | National Institute of Standards and Technology (2001), <i>Specification for the Advanced Encryption Standard (AES)</i> FIPS 197. November 26.      |
+| [NIST DSS] | NIST FIPS PUB 186-4 (2013), <i>Digital Signature Standard</i> , National Institute of Standards and Technology, U.S. Department of Commerce, July. |
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 access control** [ITU-T X.800]: The prevention of unauthorized use of a resource, including the prevention of use of a resource in an unauthorized manner.
+
+**3.1.2 authentication** [b-ISO/IEC 18014-2]: Provision of assurance in the identity of an entity.
+
+**3.1.3 authorization** [b-ITU-T X.1251]: The authorization service is designed to make decisions regarding the user's access rights and enforce authorization decisions according to the user's privileges. Authorization is an optional service; it is only provided when access to resources needs to be controlled based on the user's rights.
+
+**3.1.4 confidentiality** [ITU-T X.800]: The property that information is not made available or disclosed to unauthorized individuals, entities, or processes.
+
+**3.1.5 data integrity** [ITU-T X.800]: The property that data has not been altered or destroyed in an unauthorized manner.
+
+**3.1.6 firewall** [b-ISO/IEC 27033-1]: Type of security barrier placed between network environments – consisting of a dedicated device or a composite of several components and techniques – through which all traffic from one network environment traverses to another, and vice versa, and only authorized traffic, as defined by the local security policy, is allowed to pass.
+
+**3.1.7 intrusion detection system** [b-ISO/IEC 27039]: Information systems used to identify that an intrusion has been attempted, is occurring, or has occurred.
+
+**3.1.8 key** [ITU-T X.800]: A sequence of symbols that controls the operations of encipherment and decipherment.
+
+**3.1.9 key management** [ITU-T X.800]: The generation, storage, distribution, deletion, archiving and application of keys in accordance with a security policy.
+
+**3.1.10 public-key certificate (PKC)** [b-ITU-T X.509]: The public key of an entity, together with some other information, rendered unforgeable by digital signature with the private key of the certification authority (CA) that issued it.
+
+**3.1.11 software-defined networking** [ITU-T Y.3300]: A set of techniques that enables to directly program, orchestrate, control and manage network resources, which facilitates the design, delivery and operation of network services in a dynamic and scalable manner.
+
+**3.1.12 threat** [b-ISO/IEC 27000]: Potential cause of an unwanted incident, which may result in harm to a system or organization.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 network resources**: Network devices that can perform packet forwarding in a network system. The network resources include network switch, router, gateway, WiFi access points, and similar devices.
+
+**3.2.2 certificate management:** The creation, storage, distribution, suspension, revocation, archiving and application of certificates in accordance with a security policy.
+
+# **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|       |                                           |
+|-------|-------------------------------------------|
+| 3DES  | Triple Data Encryption Algorithm          |
+| ACL   | Access Control List                       |
+| AES   | Advanced Encryption Standard              |
+| DDoS  | Distributed Denial of Service             |
+| DoS   | Denial of Service                         |
+| DPI   | Deep Packet Inspection                    |
+| HMAC  | keyed-Hash Message Authentication Code    |
+| ICT   | Information and Communications Technology |
+| IDP   | Intrusion Detection and Prevention        |
+| IETF  | Internet Engineering Task Force           |
+| IPsec | Internet Protocol Security                |
+| MAC   | Message Authentication Code               |
+| ONF   | Open Networking Foundation                |
+| OS    | Operating System                          |
+| PSK   | Pre-Shared Key                            |
+| QoS   | Quality of Service                        |
+| RBAC  | Role Based Access Control                 |
+| SDN   | Software-Defined Networking               |
+| SLA   | Service Level Agreement                   |
+| TLS   | Transport Layer Security                  |
+
+# **5 Conventions**
+
+In this Recommendation:
+
+The keywords "**is required to**" indicate a requirement which must be strictly followed and from which no deviation is permitted, if conformance to this Recommendation is to be claimed.
+
+The keywords "**is recommended**" indicate a requirement which is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+
+The keywords "**is prohibited from**" indicate a requirement which must be strictly followed and from which no deviation is permitted, if conformance to this Recommendation is to be claimed.
+
+The keywords "**can optionally**" indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option, and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+# 6 Overview
+
+Software-defined networking (SDN) enables the administrators to configure network resources very quickly and to adjust network-wide traffic flow to meet changing needs dynamically. SDN controllers serve as a type of operating system for network. By separating the control plane from the network hardware and running the control plane instead as software, the controller facilitates automated network management, as well as integration and administration of applications and network services. However, there are some challenges for implementing a full-scale carrier SDN. One of the most important challenges is SDN security.
+
+Generally, security threats to SDN are common to other targets and to traditional networking, but the profile of the threats (including their likelihood and impact and hence their overall risk level) changes with the new SDN architecture. With a centralized SDN controller, the impact of a DoS/DDoS attack can be higher than that directed against a single router. Some new functional entities (e.g., SDN controller), protocols (e.g., ONF OpenFlow) and interfaces (e.g., application-control interface, resource-control interface) according to the framework of SDN [ITU-T Y.3300] will pose new security threats. All these security threats must be understood and secured.
+
+This Recommendation describes use cases to detail new security threats when introducing SDN. This Recommendation identifies security threats for the SDN application layer, SDN control layer, SDN resource layer, application-control interface, and resource-control interface according to the framework of SDN [ITU-T Y.3300]. This Recommendation also defines security requirements from above security threats analysis and studies possible security countermeasures against new security threats. With this information, a security reference architecture for SDN is designed based on above studies on security threats, security requirements and security countermeasures. This security reference architecture can guide the developer to design a SDN security functional architecture and implement security functions when developing an SDN controller.
+
+# 7 Security threats and requirements
+
+This clause identifies security threats for the SDN application layer, SDN control layer, resource layer, application-control interface and resource-control interface, and defines corresponding security requirements.
+
+## 7.1 SDN application layer
+
+SDN applications can be seen as the "SDN network brains", since they implement a majority of network functionalities which will be translated into flow rules to be installed in SDN resource layer and to dictate the behaviour of the forwarding devices. So, attacks on SDN applications if not stopped early enough, can impact the SDN control layer.
+
+### 7.1.1 Security threats
+
+Major security threats to SDN application layer are described as below:
+
+- **Spoofing:** An attacker masquerades as a SDN controller to get the service level agreement (SLA) or users' data (e.g., user identification, credentials) or service logic and use it for the future attack.
+- **Repudiation:** A user or an administrator, enforcing a malicious network policy (e.g., copying and forwarding specific traffic flows to a malicious server), may claim that he/she did not make such network policy enforcement.
+- **Information disclosure:** It is possible for attackers to get user's credentials and then to masquerade as a legitimate user to inject forged flows into network through SDN application.
+- **Application security vulnerabilities:** SDN applications vulnerabilities such as code flaws and insecure code could be exploited by the attacker to access resources (e.g., SLA, users' data, service logic) possessed by SDN applications to make further attacks, for example,
+
+misusing SDN network resources or reconfiguring the whole SDN network. Malicious applications or untrusted applications from the third party could masquerade as legal SDN applications to access application resources.
+
+### 7.1.2 Security requirements
+
+- R-01 It is required to provide a functionality in the SDN application layer to authenticate the SDN controller.
+- R-02 It is required to provide a functionality in the SDN application layer to authenticate the user.
+- R-03 It is required to provide a functionality in the SDN application layer to authenticate the administrator.
+- R-04 It is required to provide a functionality in the SDN application layer to authorize the user to access system information (e.g., SLA, users' data, service logic, etc.).
+- R-05 It is required to provide a functionality in the SDN application layer to authorize the administrator to access system information.
+- R-06 It is required to provide a functionality in the SDN application layer to provide confidentiality protection for system information stored in the application platform.
+- R-07 It is required to provide a functionality in the SDN application layer to support key/certificate management.
+- R-08 It is required to provide a functionality in the SDN application layer to support log and audit.
+- R-09 It is recommended to provide a functionality in the SDN application layer to support defending against application vulnerabilities.
+
+### 7.1.3 Security requirements mapping to security threats
+
+As for the SDN application layer, security requirements deriving from the corresponding security threats are shown in Table 1.
+
+**Table 1 – SDN application layer: security requirements mapping to security threats**
+
+| Security threats                   | Security requirements        |
+|------------------------------------|------------------------------|
+| Spoofing                           | R-01, R-02, R-03, R-04, R-05 |
+| Repudiation                        | R-01, R-02, R-03, R-07, R-08 |
+| Information disclosure             | R-02, R-04, R-06             |
+| Application security vulnerability | R-09                         |
+
+## 7.2 SDN control layer
+
+Securing the SDN controller is the top priority, since a compromise of the SDN controller will lead to the disaster of the entire network.
+
+### 7.2.1 Security threats
+
+Major security threats to the SDN control layer are described as follows:
+
+- **Flow rules confliction:** An example of flow rules confliction is described in use case 1 of Annex A. It explains how malicious flows could bypass security detection, which conflicts with the preconfigured security policy and will adversely affect the SDN controller.
+- **Fake flow rule insertion:** An attacker may hijack a SDN application and send some fraudulent flow rules to eavesdrop data. An example is elaborated in use case 2 of Annex A.
+- **Spoofing:** An attacker may impersonate an administrator or a SDN application to remove or modify sensitive data (e.g., configuration data, user data) from the SDN controller or to obtain network topology information and routing information or even to have complete control of
+
+the SDN controller. By spoofing the address of a SDN controller, an attacker can take the control of the entire network by creating a fake SDN controller. Moreover, an attacker may create a fake SDN switch to perform network reconnaissance by observing how the controller responds to different packets which are generated by the fake SDN switch.
+
+- **DoS attacks:** When a SDN switch encounters traffic for which it has no flow rule, it consults the SDN controller for a decision and a flow rule for future traffic of the same type. Therefore, it is possible for an attacker to create spoofed traffic to make DoS attacks on the SDN controller to cause it to fail. A spoofed SDN switch also could create DoS attacks on the SDN controller with unmanageable traffic to bog it down.
+- **Delay in blocking/mitigating attacks:** Generally network policies are converted into flow entries to be sent to SDN switches in batches periodically in order to improve system performance. Currently, the SDN controller does not support blocking/mitigating attacks in real time and the SDN controller does not automatically identify which security policies have to be operated without any delay. Therefore, security attacks will last longer and will be more severe.
+- **Repudiation:** An administrator or a SDN application, inserting malicious flow rules into the flow table to make inside attacks, may claim that he/she did not insert such malicious flow rules into the flow table.
+- **Information disclosure:** It is possible for attackers to get sensitive system information (e.g., configuration data, user credentials) for a future attack.
+- **Vulnerabilities in the operating system:** SDN controllers run on some form of operating systems (OS). If the SDN controller runs on a general purpose operating system, then the vulnerabilities of that OS become vulnerabilities for the SDN controller. An attacker may exploit vulnerabilities of the operating system such as default passwords, back-door accounts, open doors (e.g., open ports, services, and protocols), and even no security settings configured to destruct or alternate components of the OS or the complete OS, which will impact the SDN controller seriously.
+- **Vulnerabilities in software:** SDN controllers operate as a software platform. Vulnerabilities of general software become vulnerabilities for the SDN controller. A software vulnerability is a flaw, defect in software construction, weakness or even an error, which could be exploited by attackers to alter the normal behaviour of the SDN network or to reconfigure the whole network to make further attacks.
+- **Hardware failure:** Hardware failure, nothing new with information and communications technology (ICT), is a security threat representing the generic failure of hardware in SDN network elements (including controller and switch). Hardware failures will compromise network security or bring down the SDN network.
+
+### 7.2.2 Security requirements
+
+- R-10 It is required to provide a functionality in the SDN control layer to authenticate administrators.
+- R-11 It is required to provide a functionality in the SDN control layer to authorize administrators to manage the SDN controller.
+- R-12 It is required to provide a functionality in the SDN control layer to authenticate the SDN application.
+- R-13 It is required to provide a functionality in the SDN control layer to authorize the SDN application to manage network policies in the SDN controller (e.g., to insert/update/delete flow rules in the flow table).
+- R-14 It is required to provide a functionality in the SDN control layer to authenticate the SDN switch.
+
+- R-15 It is required to provide a functionality in the SDN control layer to support preventing flow rules confliction in order to avoid mandatory network policies from being bypassed.
+- R-16 It is required to provide a functionality in the SDN control layer to support anti-DoS protection.
+- R-17 It is required to provide a functionality in the SDN control layer to support log and audit.
+- R-18 It is required to provide a functionality in the SDN control layer to perform integrity protection for configuration data stored in the SDN controller.
+- R-19 It is required to provide a functionality in the SDN controller layer to perform key/certificate management.
+- R-20 It is recommended to provide a functionality in the SDN control layer to automatically block or mitigate security attacks in real time.
+- R-21 It is recommended to provide a functionality in the SDN control layer to support packet scan detection.
+- R-22 It is recommended to provide a functionality in the SDN control layer to perform confidentiality protection for configuration data stored in the SDN controller.
+- R-23 It is recommended to provide a functionality in the SDN control layer to perform confidentiality and/or integrity protection for user data stored in the SDN controller.
+- R-24 It is recommended to provide a functionality in the SDN control layer to support hardening the operating system.
+- R-25 It is recommended to provide a functionality in the SDN control layer to support software vulnerability detection and prevention.
+- R-26 It is recommended to provide a functionality in the SDN control layer to support hardware management to discover hardware failure automatically and recover from such a failure as soon as possible.
+
+### 7.2.3 Security requirements mapping to security threats
+
+As for the SDN control layer, security requirements deriving from the corresponding security threats are shown in Table 2.
+
+**Table 2 – SDN control layer: security requirements mapping to security threats**
+
+| Security threats                     | Security requirements              |
+|--------------------------------------|------------------------------------|
+| Flow rules confliction               | R-15                               |
+| Fake flow rule insertion             | R-12, R-13, R-19, R-35             |
+| Spoofing                             | R-10, R-11, R-12, R-13, R-14, R-19 |
+| DoS attacks                          | R-14, R-16, R-19                   |
+| Delay in blocking/mitigating attacks | R-20, R-21, R-33                   |
+| Repudiation                          | R-10, R-11, R-12, R-13, R-17, R-19 |
+| Information disclosure               | R-10, R-11, R-18, R-19, R-22, R-23 |
+| Vulnerabilities in operating system  | R-24                               |
+| Vulnerabilities in software          | R-25                               |
+| Hardware Failure                     | R-26                               |
+
+## 7.3 SDN resource layer
+
+### 7.3.1 Security threats
+
+Major security threats to the SDN resource layer are described as follows:
+
+- **Spoofing:** An attacker may impersonate an administrator or a SDN controller to remove or modify sensitive data (e.g., configuration data, flow table) from the SDN switch or to obtain sensitive information such as flow entries in the flow table.
+- **Eavesdropping:** An attacker may eavesdrop on flows between SDN switches to see what flows are in use, what traffic is being permitted across the network and what data contents are being transported.
+- **Information disclosure:** It is possible for attackers to get sensitive system information (e.g., flow table, configuration data) for a future attack.
+- **Flow table overflow:** Typical SDN switches have rather limited flow table capacities. The flow table capacity bottleneck leads to potential flow table overflow. Therefore, it is possible for the attacker to overwrite legitimate flow rules as flow entries of the flow table, or to make DoS and flooding attacks, or even to do inference attack [b-arXiv 2015].
+- **Repudiation:** An administrator or a SDN controller may make incorrect configuration and later claim that he/she did not do such attacks.
+
+### 7.3.2 Security requirements
+
+- R-27 It is required to provide a functionality in the SDN resource layer to authenticate administrators.
+- R-28 It is required to provide a functionality in the SDN resource layer to authorize administrators to manage SDN switches.
+- R-29 It is required to provide a functionality in the SDN resource layer to authenticate the SDN controller.
+- R-30 It is required to provide a functionality in the SDN resource layer to support log and audit.
+- R-31 It is required to provide a functionality in the SDN resource layer to perform integrity protection for configuration data stored in the SDN switch.
+- R-32 It is required to provide a functionality in the SDN resource layer to perform key/certificate management.
+- R-33 It is required to provide a functionality in the SDN resource layer to support packet scan detection, which is derived from the requirements R-20 and R-21 in clause 7.2.2, in order to automatically block or mitigate security attacks in real time. .
+- R-34 It is recommended to provide a functionality in the SDN resource layer to perform confidentiality protection for configuration data stored in the SDN switch.
+- R-35 It is recommended to provide a functionality in the SDN resource layer to perform confidentiality and/or integrity protection for data transportation between SDN switches.
+- R-36 It is recommended to provide a functionality in the SDN resource layer to prevent flow table overflow.
+
+#### 7.3.3 Security requirements mapping to security threats
+
+As for the SDN resource layer, security requirements deriving from the corresponding security threats are shown in Table 3.
+
+**Table 3 – SDN resource layer: security requirements mapping to security threats**
+
+| Security threats       | Security requirements              |
+|------------------------|------------------------------------|
+| Spoofing               | R-27, R-28, R-29, R-32             |
+| Eavesdropping          | R-35                               |
+| Information disclosure | R-31, R-32, R-34                   |
+| Flow table overflow    | R-36                               |
+| Repudiation            | R-27, R-28, R-29, R-30, R-31, R-32 |
+
+## 7.4 Application-control interface
+
+### 7.4.1 Security threats
+
+Major security threats to the application-control interface are described below:
+
+- **Eavesdropping:** An attacker can use information gathered through eavesdropping of messages to deduce network policies and to use them to elevate the attack.
+- **Tampering and intercepting:** An attacker may intercept and tamper the messages between a SDN controller and an application. If successful, the attacker could potentially subvert the SDN controller and inject his/her own network policies which would have the authority of the SDN application and thus would direct network traffic to be transported in the way as he/she wants.
+
+### 7.4.2 Security requirements
+
+- R-01 It is required to provide a functionality in the SDN application layer to authenticate the SDN controller.
+- R-07 It is required to provide a functionality in the SDN application layer to perform key/certificate management.
+- R-12 It is required to provide a functionality in the SDN control layer to authenticate the SDN application.
+- R-19 It is required to provide a functionality in the SDN controller layer to perform key/certificate management.
+- R-37 It is required to provide a functionality in the SDN control layer to perform confidentiality protection for data transportation over the application-control interface.
+- R-38 It is required to provide a functionality in the SDN control layer to perform integrity protection for data transportation over the application-control interface.
+- R-39 It is required to provide a functionality in the SDN application layer to perform confidentiality protection for data transportation over the application-control interface.
+- R-40 It is required to provide a functionality in the SDN application layer to perform integrity protection for data transportation over the application-control interface.
+- R-41 It is recommended to support TLS [IETF RFC 5246] or HTTPS [b-IETF RFC 2818] for data transportation between the SDN application and the SDN controller over the application-control interface.
+
+#### 7.4.3 Security requirements mapping to security threats
+
+As for the SDN application-control interface, security requirements deriving from the corresponding security threats are shown in Table 4.
+
+**Table 4 – SDN application-control interface:  
+security requirements mapping to security threats**
+
+| Security threats           | Security requirements                    |
+|----------------------------|------------------------------------------|
+| Eavesdropping              | R-01, R-12, R-07, R-19, R-37, R-39, R-41 |
+| Tampering and intercepting | R-01, R-12, R-07, R-19, R-38, R-40, R-41 |
+
+## 7.5 Resource-control interface
+
+### 7.5.1 Security threats
+
+Major threats to the resource-control interface are described as follows:
+
+- **Eavesdropping:** An attacker can use information gathered through eavesdropping of control messages to map out the network routing policies and to use this to elevate the attack.
+- **Tampering and intercepting:** An attacker may intercept and tamper messages between the SDN controller and switches. If successful, the attacker could potentially subvert the SDN controller and inject his/her own control messages which would have the authority of the SDN controller and thus would allow complete control of SDN switches within its scope.
+
+### 7.5.2 Security requirements
+
+- R-14 It is required to provide a functionality in the SDN control layer to authenticate the SDN switch.
+- R-19 It is required to provide a functionality in the SDN controller layer to perform key/certificate management.
+- R-29 It is required to provide a functionality in the SDN resource layer to authenticate the SDN controller.
+- R-32 It is required to provide a functionality in the SDN resource layer to perform key/certificate management.
+- R-42 It is required to provide a functionality in the SDN control layer to perform confidentiality protection for data transportation over the resource-control interface.
+- R-43 It is required to provide a functionality in the SDN control layer to perform integrity protection for data transportation over the resource-control interface.
+- R-44 It is required to provide a functionality in the SDN resource layer to perform confidentiality protection for data transportation over the resource-control interface.
+- R-45 It is required to provide a functionality in SDN resource layer to perform integrity protection for data transportation over the resource-control interface.
+- R-46 It is recommended to support TLS [IETF RFC 5246] or IPsec ([IETF RFC 4301], [IETF RFC 4303], [IETF RFC 4835]) for data transportation between the SDN controller and SDN switches over the resource-control interface.
+
+#### 7.5.3 Security requirements mapping to security threats
+
+As for the SDN resource-control interface, security requirements deriving from the corresponding security threats are shown in Table 5.
+
+**Table 5 – SDN Resource-Control interface: security requirements mapping to security threats**
+
+| Security Threats           | Security Requirements                    |
+|----------------------------|------------------------------------------|
+| Eavesdropping              | R-14, R-19, R-29, R-32, R-42, R-44, R-46 |
+| Tampering and intercepting | R-14, R-19, R-29, R-32, R-43, R-45, R-46 |
+
+# 8 Security reference architecture for SDN
+
+This clause specifies a security reference architecture to guide the developers to design a SDN security functional architecture and implement security functions when developing the SDN controller.
+
+The security reference architecture described in this Recommendation (see Figure 8-1) is based on the high-level architecture of SDN provided in [ITU-T Y.3300].
+
+![Figure 8-1: Security reference architecture for SDN. The diagram shows a multi-layer security management architecture. On the left, a vertical bar labeled 'Multi-layer security management' spans the entire stack. The architecture is divided into three main layers by dashed red lines: 1. SDN application layer (SDN-AL) at the top, containing 'Application protection', 'Security management support', 'Authentication', 'Key/certificate management', 'Data confidentiality', and 'Data integrity'. 2. SDN control layer (SDN-CL) in the middle, containing 'Authentication', 'Key/certificate management', 'Authorization', 'Supporting security monitoring', 'Data confidentiality', 'Operating system hardening', 'Data integrity', 'Security management support', 'Types of flow entries pushing to SDN switch', 'Supporting preventing flow rules confliction', 'Hardware management', and 'Detection and prevention of software vulnerability'. 3. SDN resource layer (SDN-RL) at the bottom, containing 'Authentication', 'Authorization', 'Data integrity', 'Data confidentiality', 'Key/certificate management', 'Supporting preventing flow table overflow', and 'Security management support'. Interfaces are labeled on the right: 'Application-control interface' between SDN-AL and SDN-CL, and 'Resource-control interface' between SDN-CL and SDN-RL. A reference 'X.1038(16)_F8-1' is at the bottom right.](8307f6b04df072c9332f9987e034272c_img.jpg)
+
+Figure 8-1: Security reference architecture for SDN. The diagram shows a multi-layer security management architecture. On the left, a vertical bar labeled 'Multi-layer security management' spans the entire stack. The architecture is divided into three main layers by dashed red lines: 1. SDN application layer (SDN-AL) at the top, containing 'Application protection', 'Security management support', 'Authentication', 'Key/certificate management', 'Data confidentiality', and 'Data integrity'. 2. SDN control layer (SDN-CL) in the middle, containing 'Authentication', 'Key/certificate management', 'Authorization', 'Supporting security monitoring', 'Data confidentiality', 'Operating system hardening', 'Data integrity', 'Security management support', 'Types of flow entries pushing to SDN switch', 'Supporting preventing flow rules confliction', 'Hardware management', and 'Detection and prevention of software vulnerability'. 3. SDN resource layer (SDN-RL) at the bottom, containing 'Authentication', 'Authorization', 'Data integrity', 'Data confidentiality', 'Key/certificate management', 'Supporting preventing flow table overflow', and 'Security management support'. Interfaces are labeled on the right: 'Application-control interface' between SDN-AL and SDN-CL, and 'Resource-control interface' between SDN-CL and SDN-RL. A reference 'X.1038(16)\_F8-1' is at the bottom right.
+
+**Figure 8-1 – Security reference architecture for SDN**
+
+## 8.1 SDN application layer
+
+Table 6 provides security mechanisms to meet corresponding security requirements on the SDN application layer.
+
+**Table 6 – SDN application layer: security mechanisms to meet security requirements**
+
+| Security requirements                                                                                                                                                                                      | Security mechanisms        |
+|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------|
+| R01/R02/R03 – to authenticate the SDN controller/ the user/the administrator                                                                                                                               | authentication             |
+| R04/R05 – to authorize the user/administrator to access system information                                                                                                                                 | authorization              |
+| R06/R39 – to provide confidentiality protection for system information stored in application platform/to perform confidentiality protection for data transportation over the Application-Control interface | data confidentiality       |
+| R07 – to support key/certificate management                                                                                                                                                                | key/certificate management |
+
+**Table 6 – SDN application layer: security mechanisms to meet security requirements**
+
+| Security requirements                                                                                | Security mechanisms    |
+|------------------------------------------------------------------------------------------------------|------------------------|
+| R08 – to support log and audit                                                                       | security management    |
+| R09 – support defending against application vulnerabilities                                          | application protection |
+| R40 – to perform integrity protection for data transportation over the application-control interface | data integrity         |
+
+According to Figure 8-1 and Table 6, security logical functions for the SDN application layer are described as follows:
+
+- **Authentication**
+
+The SDN application shall authenticate the SDN controller to make sure that the SDN controller is authentic, but not a fake one.
+
+There are some available authentication mechanisms including, but are not limited to, pre-shared key (PSK) based authentication [IETF RFC 4279] [IETF RFC 4306], and certificate based authentication [IETF RFC 4306] [IETF RFC 5246].
+- **Data confidentiality**
+
+Network policies (including security policies and quality-of-service (QoS) policies) shall be encrypted before being transported from the SDN applications to the SDN controller over the application-control interface in order to avoid eavesdropping attacks.
+
+Some available cryptographic algorithms used for data encryption include, but are not limited to, advanced encryption standard (AES) [AES], Blowfish [b-BLOWFISH], and triple data encryption algorithm (3DES) [b-NIST 3DES].
+- **Data integrity**
+
+Data integrity protection shall be provided for network policies (including security policies and QoS policies) while being transported from SDN applications to the SDN controller over the application-control interface in order to avoid tampering attacks.
+
+There are some available data integrity mechanisms including, but are not limited to, message authentication code (MAC) [b-IETF RFC 2104], keyed-hash message authentication code (HMAC) [b-IETF RFC 2104], and digital signature [DSS].
+- **Key/certificate management**
+
+Key/certificate management shall refer to key management defined in [ITU-T X.800] and certificate management protocol defined in [IETF RFC 4210].
+- **Application protection**
+
+Attack detection tools (e.g., intrusion detection systems, application firewalls) should be applied in the SDN application layer to protect applications at runtime. Attack detection tools use approaches based on either anomaly detection or signatures [b-PRDC2009]. Anomaly-detection-based tools are based on a baseline for network behaviour to detect any behaviour that fall outside the predefined or accepted model of behaviour. Signature-based tools look for patterns of a predefined set of rules or signatures indicating an attack. Anomaly-detection-based tools perform better for simpler applications, while signature-based tools are better for more complex applications.
+
+Before installing an application, real-time verification shall be provided that the application certification is current and valid in order to make sure that this application is from trusted third party.
+
+- Security management support  
+Security management support shall be provided to the support for the function multi-layer security management which is described in clause 8.4.
+
+## 8.2 SDN control layer
+
+Table 7 provides security mechanisms to meet corresponding security requirements for the SDN control layer.
+
+**Table 7 – SDN control layer: security mechanisms to meet security requirements**
+
+| Security requirements                                                                                                                                                                                                                                                                                                                                                                                | Security mechanisms                                |
+|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------|
+| R10/R12/R14 – to authenticate administrators/SDN application/SDN switch                                                                                                                                                                                                                                                                                                                              | authentication                                     |
+| R11/R13 – to authorize administrators/SDN application to manage the SDN controller                                                                                                                                                                                                                                                                                                                   | authorization                                      |
+| R15 – to support prevent flow rules confliction                                                                                                                                                                                                                                                                                                                                                      | preventing flow rules confliction                  |
+| R16 – to support anti-DoS protection                                                                                                                                                                                                                                                                                                                                                                 | authentication, security management                |
+| R17 – to support log and audit                                                                                                                                                                                                                                                                                                                                                                       | security management                                |
+| R18/R23/R38/R43 – to perform integrity protection for configuration data stored in the SDN controller/ to perform integrity protection for user data stored in the SDN controller/ to perform integrity protection for data transportation over the application-control interface/ to perform integrity protection for data transportation over the resource-control interface                       | data integrity                                     |
+| R19 – to perform key/certificate management                                                                                                                                                                                                                                                                                                                                                          | key/certificate management                         |
+| R20 – to block or mitigate security attacks in real time and automatically                                                                                                                                                                                                                                                                                                                           | types of flow entries being pushed to SDN switches |
+| R21 – to support packet scan detection                                                                                                                                                                                                                                                                                                                                                               | supporting security monitoring                     |
+| R22/R23/R37/R42 – to perform confidentiality protection for configuration data stored in the SDN controller/to perform confidentiality protection for user data stored in the SDN controller/ to perform confidentiality protection for data transportation over the application-control interface/to perform confidentiality protection for data transportation over the resource-Control interface | data confidentiality                               |
+| R24 – to support hardening operating system                                                                                                                                                                                                                                                                                                                                                          | operating system hardening                         |
+| R25 – to support software vulnerability detection and prevention                                                                                                                                                                                                                                                                                                                                     | detection and prevention of software vulnerability |
+| R26 – to support hardware management to discover hardware failure automatically and recover from such a failure as soon as possible                                                                                                                                                                                                                                                                  | hardware management                                |
+
+According to Figure 8-1 and Table 7, security logical functions for the SDN control layer are described as follows:
+
+- Authentication  
+The SDN controller shall authenticate the SDN application to make sure that the SDN application is authentic, but not a fake one.  
+The SDN controller shall authenticate the SDN switch to make sure that the SDN switch is authentic, but not a fake one.
+
+The SDN controller shall authenticate administrators to make sure that these administrators are authentic.
+
+There are some available authentication mechanisms including, but are not limited to, username/password based authentication, PSK (pre-shared key) based authentication [IETF RFC 4279] [IETF RFC 4306], and certificate based authentication [IETF RFC 4306] [IETF RFC 5246].
+
+### - Authorization
+
+SDN applications and administrators access to the SDN controller shall comply with access control policies.
+
+Some available access control mechanisms include, but are not limited to, whitelist/blacklist [b-IETF RFC 5782] [b-IETF RFC 5851], access control list (ACL) [IETF RFC 4314] [b-IETF RFC 4949], role based access control (RBAC) [b-INCITS RBAC].
+
+### - Data confidentiality
+
+Network policies (including security policies and QoS policies) from the SDN application layer shall be decrypted by the SDN controller before being interpreted as flow rules.
+
+Flow rules/entries shall be encrypted before being transported from the SDN controller to SDN switches over the resource-control interface in order to avoid eavesdropping attacks.
+
+Flow rule inquiries from the SDN switches shall be decrypted by the SDN controller before the SDN controller looks for corresponding flow rules.
+
+Configuration data from the SDN management console shall be decrypted by the SDN controller before being updated into corresponding configuration component in the SDN controller.
+
+Some sensitive data (e.g., configuration data, user data) shall be encrypted and stored in the SDN controller to prevent data theft.
+
+Some available cryptographic algorithms used for data encryption include, but are not limited to, AES [AES], Blowfish [b-BLOWFISH], and 3DES [b-NIST 3DES].
+
+### - Data integrity
+
+Data integrity validation for network policies (including security policies and QoS policies) from SDN applications shall be operated by the SDN controller before being interpreted as flow rules.
+
+Data integrity protection shall be provided for flow rules/entries while being transported from the SDN controller to the SDN switches over the resource-control interface in order to avoid tampering attacks.
+
+Data integrity validation for flow rule inquiries from SDN switches shall be operated by the SDN controller before the SDN controller looks for corresponding flow rules.
+
+Data integrity validation for some configuration data from the SDN management console shall be operated by the SDN controller before being updated into corresponding configuration component in the SDN controller.
+
+Data integrity protection shall be provided for some sensitive data (e.g., configuration data, user data) while storing in the SDN controller to prevent them from tampering.
+
+There are some available data integrity mechanisms including, but are not limited to, MAC (Message authentication code) [b-IETF RFC 2104], HMAC [b-IETF RFC 2104], and digital signature [DSS].
+
+### - Key/certificate management
+
+Key/certificate management shall refer to key management defined in [ITU-T X.800] and certificate management protocol defined in [IETF RFC 4210].
+
+- Types of flow entries being pushed to SDN switches  
+ There are two types of flow entries being pushed to SDN switches: real-time push and periodic push.  
+ Some flow rules/entries are used to block or mitigate security attacks which are detected by security applications (e.g., firewall, deep packet inspection (DPI), and intrusion detection and prevention (IDP)). Those flow entries have to be pushed to SDN switches in real time.  
+ Some flow rules/entries can be operated with some delay. Those flow entries shall be pushed to SDN switches in batches periodically in order to improve system performance.  
+ One suitable solution is to add a new attribute to a flow rule in order to indicate the flow entry to be pushed to SDN switches in real time or sometime later [b-ICIN2015 SDNSEC]. With that attribute, the SDN controller could distinguish the flow entries need to be pushed to SDN switches in real time from those flow entries need to be pushed to SDN switches periodically.
+- Preventing flow rules confliction  
+ Currently, the SDN controller cannot distinguish the application generating the new flow entry from another application generating the old entry. So, it is possible for an application to create a new flow entry to replace the flow entry which reflects a mandatory policy predefined by a security administrator. One of the use cases is described in clause A.1. Therefore, the SDN controller should have the ability to judge if an application has the right to insert/update/delete the flow entry in the flow table in order to avoid flow rules conflicting.  
+ One of suitable solutions is to support fine-grained naming scheme for flow entry [b-ICIN2015 SDNSEC], which is described in clause B.1.
+- Supporting security monitoring  
+ The module of supporting security monitoring is to enable administrators to monitor the entire SDN network, especially on security policies enforcement. For example, a security administrator wants to know the details regarding a security policy for a specified data flow and sends a request to the supporting security monitoring module. This module retrieves related information (e.g., flow entries, flow entries generators, security policies, etc.) from flow tables, then analyses the retrieved information, generates a report and displays the report to the security administrator.
+- Operating system hardening  
+ The purpose of operating system hardening is to eliminate as many security risks as possible and to make an operating system more secure. It often requires numerous actions such as configuring system and network components properly, deleting unused files, removing all non-essential software programs, applying the latest patches, reformatting the hard disk and only installing the bare necessities that the server needs to function, disabling guest account, and renaming the administrator account.
+- Detection and prevention of software vulnerability  
+ In order to understand and prevent vulnerabilities, software vulnerability detection should be performed first. There are two main categories of automated methods for software vulnerability detection: static detection (e.g., pattern matching and data flow analysis) which is performed without running the source code; and dynamic detection (e.g., fault injection, fuzzing testing) which is performed when the program is executed. Usually, a hybrid combination of both techniques is used.  
+ Two possible vulnerability prevention methods developed in the literature are software inspection (e.g., security goal indicator trees [b-HASE2008] and vulnerability inspection diagram [b-SHIELDS]) and security activity graph [b-ICSE2006],[ b-ARES2008].
+
+- **Hardware management**  
+The hardware management system against hardware failures arisen from the SDN network shall be based on a management model constructed as a relational database to visually manage network elements and their correlative relationships [b-IFIP2015 IM]. With a hardware management system, a hardware failure can be detected timely and network elements affected can be specified. Therefore, the network administrator can work on recovery operations faster and earlier and enhance availability of the network.
+- **Security management support**  
+Security management support shall provide the support for the function multi-layer security management which is described in clause 8.4.
+
+## 8.3 SDN resource layer
+
+Table 8 provides security mechanisms to meet corresponding security requirements for the SDN application layer.
+
+**Table 8 – SDN resource layer: security mechanisms to meet security requirements**
+
+| Security requirements                                                                                                                                                                                                                                                                      | Security mechanisms            |
+|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------|
+| R27/29 – to authenticate administrators/SDN controller                                                                                                                                                                                                                                     | authentication                 |
+| R28 – to authorize administrators to manage SDN switches                                                                                                                                                                                                                                   | authorization                  |
+| R30 – to support log and audit                                                                                                                                                                                                                                                             | security management            |
+| R31/R35/R45 – to perform integrity protection for configuration data stored in the SDN switch/ to perform integrity protection for data transportation between SDN switches/ to perform integrity protection for data transportation over the resource-control interface                   | data integrity                 |
+| R32 – to perform key/certificate management                                                                                                                                                                                                                                                | key/certificate management     |
+| R34/R35/R44 – to perform confidentiality protection for configuration data stored in the SDN switch/ to perform confidentiality protection for data transportation between SDN switches/ to perform confidentiality protection for data transportation over the resource-control interface | data confidentiality           |
+| R36 – to prevent flow table overflow                                                                                                                                                                                                                                                       | preventing flow table overflow |
+
+According to Figure 8-1 and Table 8, security logical functions for the SDN resource layer are described as follows:
+
+- **Authentication**  
+The SDN switch shall authenticate the SDN controller to make sure that the SDN controller is authentic, but not a fake one.  
+The SDN switch shall authenticate administrators to make sure that these administrators are authentic.  
+There are some available authentication mechanisms including, but are not limited to, username/password based authentication, PSK (pre-shared key) based authentication [IETF RFC 4279] [IETF RFC 4306], and certificate based authentication [IETF RFC 4306] [IETF RFC 5246].
+- **Authorization**  
+The SDN controller and administrators access to the SDN switch shall comply with access control policies.
+
+Some available access control mechanisms include, but are not limited to, whitelist/blacklist [b-IETF RFC 5782] [b-IETF RFC 5851], access control list (ACL) [IETF RFC 4314] [b-IETF RFC 4949], role based access control (RBAC) [b-INCITS RBAC].
+
+### - Data confidentiality
+
+Flow rules/entries from the SDN controller shall be decrypted by SDN switches before being updated into flow table.
+
+Flow rule inquiries shall be encrypted before being transported from SDN switches to the SDN controller over resource-control interface in order to avoid eavesdropping attacks.
+
+Configuration data from the SDN management console shall be decrypted by SDN switches before being updated into corresponding configuration component in SDN switches.
+
+Some sensitive data (e.g., configuration data, user data) shall be encrypted and stored in SDN switches to prevent data theft.
+
+Some available cryptographic algorithms used for data encryption include, but are not limited to, AES [AES], Blowfish [b-BLOWFISH], and 3DES [b-NIST 3DES].
+
+### - Data integrity
+
+Data integrity validation for flow rules/entries from the SDN controller shall be operated by SDN switches before being updated into flow table.
+
+Data integrity protection shall be provided for flow rule inquiries while being transported from SDN switches to the SDN controller over resource-control interface in order to avoid tampering attacks.
+
+Data integrity validation for configuration data from the SDN management console shall be operated by SDN switches before being updated into corresponding configuration component in SDN switches.
+
+Data integrity protection shall be provided for some sensitive data (e.g., configuration data, user data) while stored in SDN switches to prevent them from tampering.
+
+There are some available data integrity mechanisms including, but are not limited to, MAC (Message authentication code) [b-IETF RFC 2104], HMAC [b-IETF RFC 2104], and digital signature [DSS].
+
+### - Key/certificate management
+
+Key/certificate management shall refer to key management defined in [ITU-T X.800] and certificate management protocol defined in [IETF RFC 4210].
+
+#### - Preventing flow table overflow
+
+Except for some general countermeasures of buffer overflow (e.g., pointer protection, executable space protection) for preventing flow table overflow, current SDN switches and flow table designs should be improved [b-arXiv 2015]. For flow table maintenance, the SDN switch itself can decide which flow entry to delete and then sync with the SDN controller.
+
+### - Security management support
+
+Security management support shall provide the support for the function multi-layer security management which is described in clause 8.4.
+
+## 8.4 Multi-layer security management
+
+The logical function multi-layer security management is to provide security configuration and management for the SDN application layer, control layer and resource layer, including:
+
+- to control access to platform-specific resources according to security policies so that the platform cannot be sabotaged (intentionally or unintentionally);
+
+- to monitor users logging on to a platform, refusing access to those who enter inappropriate access codes, making a platform-specific minimum configuration, enforcing security policies on operating system and application system;
+- to use aggregate information and statistics for the purposes of monitoring attacks on the platform.
+
+For the application-control interface, it is recommended that TLS [IETF RFC 5246] or HTTPS [b-IETF RFC 2818] protocols are implemented and deployed in the SDN application and the SDN controller to provide mutual authentication between the SDN application and the SDN controller, as well as to provide data confidentiality and data integrity for data transportation over the application-control interface.
+
+For the resource-control interface, it is recommended that TLS [IETF RFC 5246] or IPSec protocols ([IETF RFC 4301], [IETF RFC 4303], [IETF RFC 4835]) are implemented and deployed in the SDN controller and SDN switches to provide mutual authentication between the SDN controller and SDN switches, as well as to provide data confidentiality and data integrity for data transportation over the resource-control interface.
+
+# Annex A
+
+## Use cases of new security threats to SDN
+
+(This annex forms an integral part of this Recommendation.)
+
+In this annex, the following use cases are illustrated to describe new security threats when introducing SDN.
+
+## A.1 Use case 1: Bypassing a predefined mandatory policy
+
+SDN applications are programs that explicitly, directly, and programmatically communicate their network requirements and desired network behaviour (i.e., network policies) to the SDN controller via application-controller interfaces. The controller converts these network policies into flow entries and inserts them into the flow table. However, currently a flow entry in OpenFlow flow table does not distinguish the application generating the new flow entry from another application generating the old flow entry. So, it is possible that a new network policy generated by a general application can replace a non-bypass security policy predefined by the security administrator. In Figure A.1, the security administrator proactively configures a non-bypass security policy as follows: the packets must be sent to the firewall for packet scan detection if these packets are delivered from Host A (172.0.0.1) to Host B (172.0.0.2), as data transportation path\_1 in green (*the path\_1: Host A -> SDN\_Switch\_1 -> SDN\_Switch\_2 -> Firewall -> SDN\_Switch\_3 -> Host B*). Sometime later, the application App\_X needs the shortest path for data transportation with low delay and generates the policy as follows: the shortest transportation path will be selected if these packets are delivered from Host A (172.0.0.1) to Host B (172.0.0.2), as data transportation path\_2 in brown (*the path\_2: Host A -> SDN\_Switch\_1 -> SDN\_Switch\_3 -> Host B*). According to the format of the flow entry in OpenFlow flow table, the controller will replace the former non-bypass security policy with the later shortest path policy. This subverts security administrator intention and the mandatory security policy will be bypassed. Thus, it is possible that malicious flows bypass security detection and will adversely affect the SDN controller.
+
+![Diagram illustrating bypassing a predefined mandatory policy in an SDN network. The network includes a Security Mgmt. server, Application App_X, SDN controller, and five SDN switches (1-5) connected to Host A and Host B. A Firewall is also present. Two data paths are shown: Path 1 (green dashed) and Path 2 (orange dashed).](cbdfdade780e677eb1c1aef3081ce9ef_img.jpg)
+
+Security Mgmt. server  
+(e.g., mandatory security policy)
+
+Application App\_X  
+(e.g., requesting for better QoS)
+
+SDN  
+controller
+
+Security policies
+
+General policies
+
+Flow entries
+
+SDN\_Switch\_5  
+10.0.0.5
+
+SDN\_Switch\_4  
+10.0.0.4
+
+SDN\_Switch\_1  
+10.0.0.1
+
+SDN\_Switch\_2  
+10.0.0.2
+
+FireWall
+
+SDN\_Switch\_3  
+10.0.0.3
+
+Host A  
+172.0.0.1
+
+Host B  
+172.0.0.2
+
+Data transportation path\_1  
+Data transportation path\_2
+
+X.1038(16)\_FA.1
+
+Diagram illustrating bypassing a predefined mandatory policy in an SDN network. The network includes a Security Mgmt. server, Application App\_X, SDN controller, and five SDN switches (1-5) connected to Host A and Host B. A Firewall is also present. Two data paths are shown: Path 1 (green dashed) and Path 2 (orange dashed).
+
+**Figure A.1 – Bypassing a predefined mandatory policy**
+
+### **A.2 Use case 2: Data eavesdropping attacks by inserting fraudulent flow entries**
+
+An attacker may hijack a SDN application and insert fraudulent flow entries to make data eavesdropping attacks. In Figure A.2, the attacker hijacks the SDN application to generate the policy as follows: the packets are copied and forwarded to the attacker with IP address 192.0.0.10 if these packets are delivered from Host A (172.0.0.1) to Host B (172.0.0.2). This policy is converted into a flow entry then inserted into SDN\_Switch\_1 flow tables through the message *OFPT\_Flow\_MOD* from the controller. In this way, the attacker can easily intercept the packets from Host A to Host B.
+
+![Diagram illustrating data eavesdropping attacks by inserting fraudulent flow entries in an SDN network.](aaf3e6e44cdeabd6d1df869c5f392ea1_img.jpg)
+
+The diagram illustrates a data eavesdropping attack in an SDN network. At the top, a **Hijacked application** (represented by server icons) sends **Illegal policies** to an **SDN controller** (server icon). The SDN controller then distributes **Flow entries** to the network switches. The network consists of five SDN switches: **SDN\_Switch\_1**, **SDN\_Switch\_2**, **SDN\_Switch\_3**, **SDN\_Switch\_4**, and **SDN\_Switch\_5**, connected in a mesh topology. A **FireWall** is also present, connected to SDN\_Switch\_2 and SDN\_Switch\_3. Three external entities are shown: **Attacker 192.0.0.10** (laptop icon), **Host A 172.0.0.1** (laptop icon), and **Host B 172.0.0.2** (laptop icon). A green dashed line represents **Data transportation**, showing a path from Host A through SDN\_Switch\_1, SDN\_Switch\_2, and SDN\_Switch\_3 to Host B. An orange dashed line represents **Data forwarding to the attacker**, showing a path from Host A through SDN\_Switch\_1 and SDN\_Switch\_4 to the Attacker. A legend at the bottom left clarifies these paths: a green dashed line for "Data transportation" and an orange dashed line for "Data forwarding to the attacker".
+
+X.1038(16)\_FA.2
+
+Diagram illustrating data eavesdropping attacks by inserting fraudulent flow entries in an SDN network.
+
+**Figure A.2 – Data eavesdropping attacks by inserting fraudulent flow entries**
+
+# **Annex B**
+
+## **Fine-grained naming scheme for flow entry**
+
+(This annex forms an integral part of this Recommendation.)
+
+In this annex, suitable security mechanisms are provided to meet new security requirements in order to prevent new security threats when introducing SDN.
+
+## **B.1 Fine-grained naming scheme for flow entry**
+
+A fine-grained naming scheme for flow entry [b-ICIN2015 SDNSEC] stored in the SDN controller is proposed to avoid mandatory network policies from being bypassed.
+
+Currently the components "match fields" and "priority" are taken together to identify a unique flow entry in the OpenFlow flow table. In this way, a flow entry in the flow table does not distinguish a SDN application generating the new flow entry from another SDN application generating the old flow entry. So, it is possible for a SDN application to create a new flow entry to replace the flow entry which reflects a mandatory policy predefined by a security administrator.
+
+In order to design a fine-grained naming scheme for the flow entry, two new features will be added. One is the role of policy creator, the other is the level of the security privilege of the role.
+
+The role of policy creator is used to define the role of the administrator/application that creates a given network policy. The role of creator may be a security administrator, a general administrator, a user, or a guest.
+
+The security privilege level of the role is used to specify different security privilege levels for different roles of policy creators. Hierarchical levels from the highest to the lowest may be L5, L4, L3, L2, L1, and L0. The role with the relatively higher security privilege level is given more rights to access the SDN controller. For example, the policy created by the creator with relatively low security privilege level is replaced by the policy created by the creator with a higher level. In one illustrative embodiment, security privilege levels of roles can be set as follows: security administrator – L5 (highest); general administrator – L4; user – L2; and guest – L1. It is to be understood that, in this illustrative embodiment, there is no dedicated role for security privilege levels L3 and L0. However, the quantity and assignment of security privilege levels is open to the developer and can be instantiated based on the specific needs of the SDN network design. Overwriting policy by role level as above may not work for heterogeneous networks, since the definition of role level for those networks may be different.
+
+With the above two new additional features to describe a flow entry defined in the SDN controller, the new flow entry can be inserted into the flow table correctly since the flow entry created by the security administrator with a high security privilege level cannot be replaced by the new flow entry created by a SDN application with a low security privilege level. In this way, mandatory network policies will not be overwritten and bypassed.
+
+There is no impact on the resource-controller interface and flow tables of switches since these two features are stored in the controller to help the controller make decision when updating flow entries.
+
+# Bibliography
+
+- [b-ITU-T X.509] Recommendation ITU-T X.509 (2012) | ISO/IEC 9594-8:2014, *Information technology – Open Systems Interconnection – The Directory: Public-key and attribute certificate frameworks.*
+- [b-ITU-T X.1251] Recommendation ITU-T X.1251 (2012), *A framework for user control of digital identity.*
+- [b-ISO/IEC 18014-2] ISO/IEC 18014-2:2009, *Information technology – Security techniques – Time-stamping services – Part 2: Mechanisms producing independent tokens.*
+- [b-ISO/IEC 27000] ISO/IEC 27000:2014, *Information technology – Security techniques – Information security management systems – Overview and vocabulary.*
+- [b-ISO/IEC 27039] ISO/IEC 27039:2015, *Information technology – Security techniques – Selection, deployment and operations of intrusion detection and prevention systems (IDPS).*
+- [b-ISO/IEC 27033-1] ISO/IEC 27033-1:2015, *Information technology – Security techniques – Network security – Part 1: Overview and concepts.*
+- [b-IETF RFC 2104] IETF RFC 2104 (1997), *HMAC: Keyed-Hashing for Message Authentication.* URL: [www.ietf.org/rfc/rfc2104.txt](http://www.ietf.org/rfc/rfc2104.txt)
+- [b-IETF RFC 2818] IETF RFC 2818 (2000), *HTTP Over TLS.*
+- [b-IETF RFC 4949] IETF RFC 4949 (2007), *Internet Security Glossary, Version 2.*
+- [b-IETF RFC 5782] IETF RFC 5782 (2010), *DNS Blacklists and Whitelists.*
+- [b-IETF RFC 5851] IETF RFC 5851 (2010), *Framework and Requirements for an Access Node Control Mechanism in Broadband Multi-Service Networks.*
+- [b-ARES2008] Byers, D., Shahmehri, N. (2008), *A Cause-Based Approach to Preventing Software Vulnerabilities.* ARES, pp. 276-283, Third International Conference on Availability, Reliability and Security.
+- [b-arXiv 2015] Leng, J., Zhou, Y., Zhang, J., and Hu, C. (2015), *An Inference Attack Model for Flow Table Capacity and Usage: Exploiting the Vulnerability of Flow Table Overflow in Software-Defined Network,* arXiv:1504.03095.
+- [b-BLOWFISH] Schneier, B. (1994), *The Blowfish Encryption Algorithm,* Dr. Dobb's Journal, v. 19, n. 4, April.
+- [b-HASE2008] Peine, H., Jawurek, M., and Mandel, S. (2008), *Security Goal Indicator Trees: A Model of Software Features that Supports Efficient Security Inspection.* HASE, pp. 9-18, 11th IEEE High Assurance Systems Engineering Symposium.
+- [b-ICIN 2015 SDNSEC] Hu Z., Wang, M., Yan, X., Yin, Y. and Luo, Z. (2015), *A Comprehensive Security Architecture for SDN,* 18th International Conference on Intelligence in Next Generation Networks, IEEE, pp. 30-37.
+- [b-INCITS RBAC] INCITS 359-2012: *Information Technology – Role Based Access Control.*
+- [b-ICSE 2006] Ardi, S., Byers, D., and Shahmehri, N. (2006), *Towards a Structured Unified Process for Software Security.* In Proceedings of the ICSE 2006
+
+Workshop on Software Engineering for Secure Software (SESS06), Shanghai, China.
+
+- [b-IFIP 2015 IM] Miyazawa, T., Furukawa, H., Torita, T., Sugawara, M., Kinugasa, M., Yashima, E., and Harai, H. (2015), *Management architecture against hardware failures in an optical packet and circuit integrated network*. Integrated Network Management (IM), IFIP IEEE 2015, pp. 665-671.
+- [b-ONF OpenFlow] *OpenFlow Switch Specification Version 1.4.0*, Open Networking Foundation. URL: [www.opennetworking.org/sdn-resources/technical-library](http://www.opennetworking.org/sdn-resources/technical-library)
+- [b-PRDC2009] Antunes, N. and Vieira, M. (2009), *Comparing the Effectiveness of Penetration Testing and Static Code Analysis on the Detection of SQL Injection Vulnerabilities in Web Services*, Proc. 15th IEEE Pacific Rim International Symposium on Dependable Computing (PRDC 09), IEEE CS, 2009, pp. 301-306.
+- [b-SHIELDS] SHIELDS Project Consortium. D2.1 *Formalism Definitions and Representation Schemata*. SHIELDS Project Deliverable D2.1. [www.cspforum.eu/D2.1\\_Formalism\\_Definitions\\_and\\_Representation\\_Schemata.pdf](http://www.cspforum.eu/D2.1_Formalism_Definitions_and_Representation_Schemata.pdf).
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | General tariff principles                                                                                                                                 |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| Series F        | Non-telephone telecommunication services                                                                                                                  |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Terminals and subjective and objective assessment methods                                                                                                 |
+| Series Q        | Switching and signalling                                                                                                                                  |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| <b>Series X</b> | <b>Data networks, open system communications and security</b>                                                                                             |
+| Series Y        | Global information infrastructure, Internet protocol aspects and next-generation networks, Internet of Things and smart cities                            |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

marked/X/T-REC-X.1039-201610-I_PDF-E/raw.md

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+
+
+I n t e r n a t i o n a l   T e l e c o m m u n i c a t i o n   U n i o n
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**X.1039**
+
+(10/2016)
+
+SERIES X: DATA NETWORKS, OPEN SYSTEM  
+COMMUNICATIONS AND SECURITY
+
+Information and network security – Network security
+
+# --- **Technical security measures for implementation of ITU-T X.805 security dimensions**
+
+Recommendation ITU-T X.1039
+
+## ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY
+
+|                                                        |                      |
+|--------------------------------------------------------|----------------------|
+| PUBLIC DATA NETWORKS                                   | X.1–X.199            |
+| OPEN SYSTEMS INTERCONNECTION                           | X.200–X.299          |
+| INTERWORKING BETWEEN NETWORKS                          | X.300–X.399          |
+| MESSAGE HANDLING SYSTEMS                               | X.400–X.499          |
+| DIRECTORY                                              | X.500–X.599          |
+| OSI NETWORKING AND SYSTEM ASPECTS                      | X.600–X.699          |
+| OSI MANAGEMENT                                         | X.700–X.799          |
+| SECURITY                                               | X.800–X.849          |
+| OSI APPLICATIONS                                       | X.850–X.899          |
+| OPEN DISTRIBUTED PROCESSING                            | X.900–X.999          |
+| INFORMATION AND NETWORK SECURITY                       |                      |
+| General security aspects                               | X.1000–X.1029        |
+| <b>Network security</b>                                | <b>X.1030–X.1049</b> |
+| Security management                                    | X.1050–X.1069        |
+| Telebiometrics                                         | X.1080–X.1099        |
+| SECURE APPLICATIONS AND SERVICES                       |                      |
+| Multicast security                                     | X.1100–X.1109        |
+| Home network security                                  | X.1110–X.1119        |
+| Mobile security                                        | X.1120–X.1139        |
+| Web security                                           | X.1140–X.1149        |
+| Security protocols                                     | X.1150–X.1159        |
+| Peer-to-peer security                                  | X.1160–X.1169        |
+| Networked ID security                                  | X.1170–X.1179        |
+| IPTV security                                          | X.1180–X.1199        |
+| CYBERSPACE SECURITY                                    |                      |
+| Cybersecurity                                          | X.1200–X.1229        |
+| Countering spam                                        | X.1230–X.1249        |
+| Identity management                                    | X.1250–X.1279        |
+| SECURE APPLICATIONS AND SERVICES                       |                      |
+| Emergency communications                               | X.1300–X.1309        |
+| Ubiquitous sensor network security                     | X.1310–X.1339        |
+| PKI related Recommendations                            | X.1340–X.1349        |
+| CYBERSECURITY INFORMATION EXCHANGE                     |                      |
+| Overview of cybersecurity                              | X.1500–X.1519        |
+| Vulnerability/state exchange                           | X.1520–X.1539        |
+| Event/incident/heuristics exchange                     | X.1540–X.1549        |
+| Exchange of policies                                   | X.1550–X.1559        |
+| Heuristics and information request                     | X.1560–X.1569        |
+| Identification and discovery                           | X.1570–X.1579        |
+| Assured exchange                                       | X.1580–X.1589        |
+| CLOUD COMPUTING SECURITY                               |                      |
+| Overview of cloud computing security                   | X.1600–X.1601        |
+| Cloud computing security design                        | X.1602–X.1639        |
+| Cloud computing security best practices and guidelines | X.1640–X.1659        |
+| Cloud computing security implementation                | X.1660–X.1679        |
+| Other cloud computing security                         | X.1680–X.1699        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T X.1039
+
+# Technical security measures for implementation of ITU-T X.805 security dimensions
+
+## Summary
+
+Many organizations in developing countries as well as developed countries may have difficulties in implementing the high-level dimensions described in Recommendation ITU-T X.805. Recommendation ITU-T X.1039 is aimed at providing a set of security measures to implement the high-level dimensions. It also provides technical implementation guidance for security measures that can be used to improve organizations' security response capabilities. A set of security measures described in this Recommendation could assist organizations in managing information security risks and implementing technical dimensions. The audience of this Recommendation includes, but is not limited to, those individuals responsible for implementing an organization's information security dimensions.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T X.1039   | 2016-10-14 | 17          | <a href="http://handle.itu.int/11.1002/1000/13059">11.1002/1000/13059</a> |
+
+## Keywords
+
+Security dimension, security measures, technical implementation guidance.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2017
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                   | Page |
+|-------------------------------------------------------------------|------|
+| 1 Scope.....                                                      | 1    |
+| 2 References.....                                                 | 1    |
+| 3 Definitions .....                                               | 1    |
+| 3.1 Terms defined elsewhere.....                                  | 1    |
+| 3.2 Terms defined in this Recommendation.....                     | 2    |
+| 4 Abbreviations and acronyms .....                                | 2    |
+| 5 Conventions .....                                               | 3    |
+| 6 Overview of information security measures.....                  | 3    |
+| 7 Information security measures.....                              | 4    |
+| 7.1 Access control .....                                          | 4    |
+| 7.2 Authentication .....                                          | 4    |
+| 7.3 Non-repudiation.....                                          | 5    |
+| 7.4 Data confidentiality .....                                    | 6    |
+| 7.5 Communication security.....                                   | 6    |
+| 7.6 Data integrity .....                                          | 8    |
+| 7.7 Availability .....                                            | 8    |
+| 7.8 Privacy.....                                                  | 9    |
+| Annex A – Additional technical implementation guidance .....      | 10   |
+| A.1 Secure configuration.....                                     | 10   |
+| A.2 Malware protection.....                                       | 10   |
+| A.3 Patch management.....                                         | 11   |
+| A.4 Vulnerability management .....                                | 11   |
+| A.5 Information security incidents management .....               | 11   |
+| A.6 System development security .....                             | 12   |
+| A.7 Authentication for information systems and applications ..... | 12   |
+| A.8 Data leakage prevention .....                                 | 13   |
+| A.9 Operations security .....                                     | 13   |
+| A.10 Backup and disaster recovery .....                           | 13   |
+| A.11 Desktop PC and mobile device protection .....                | 13   |
+| Appendix I – Organizational implementation guidance .....         | 15   |
+| I.1 Information security policies .....                           | 15   |
+| I.2 Organization of information security .....                    | 15   |
+| I.3 Human resources security .....                                | 16   |
+| I.4 Asset management .....                                        | 17   |
+| I.5 Physical and environment security .....                       | 17   |
+| I.6 Supplier relationship .....                                   | 18   |
+| Appendix II – Level of security assurance.....                    | 19   |
+
+|                                                                                                      | <b>Page</b> |
+|------------------------------------------------------------------------------------------------------|-------------|
+| II.1 Level of assurance for entity authentication [b-ITU-T X.1254] .....                             | 19          |
+| II.2 Level of security assurance .....                                                               | 19          |
+| Appendix III – Guidance on assigning specific level of security assurance from the final index ..... | 20          |
+| III.1 Methodology for level of security assurance.....                                               | 20          |
+| Appendix IV – SGSN specific implementation guideline.....                                            | 21          |
+| IV.1 Overview .....                                                                                  | 21          |
+| IV.2 Access control dimension for module 1 .....                                                     | 21          |
+| IV.3 Availability dimension for module 1 .....                                                       | 21          |
+| IV.4 Non repudiation dimension for module 1 .....                                                    | 22          |
+| IV.5 Authentication dimension for module 1 .....                                                     | 22          |
+| IV.6 Data integrity dimension for module.....                                                        | 22          |
+| IV.7 Privacy and data confidentiality dimension for module 1 .....                                   | 22          |
+| IV.8 Communication security dimension for module 1 .....                                             | 22          |
+| Bibliography.....                                                                                    | 23          |
+
+# Recommendation ITU-T X.1039
+
+# Technical security measures for implementation of ITU-T X.805 security dimensions
+
+# 1 Scope
+
+This Recommendation provides technical security measures for the implementation of [ITU-T X.805] security dimensions, which includes access control, communication security, authentications, and data confidentiality. It also provides examples for applying the set of technical security measures to the organizations with practical levels of information security dimensions, etc. in the appendices. It is not intended to cover all security measures, but to focus on several technical issues.
+
+This Recommendation is applicable to all type of telecommunication organizations, including those in the developing countries.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T X.805] Recommendation ITU-T X.805 (2003), *Security architecture for systems providing end-to-end communications*.
+
+# 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 access control** [b-ITU-T X.800]: The prevention of unauthorized use of a resource, including the prevention of use of a resource in an unauthorized manner.
+
+**3.1.2 authentication** [b-ITU-T X.1254]: Provision of assurance in the identity of an entity.
+
+**3.1.3 authorization** [b-ITU-T X.1254]: The granting of rights, which includes the granting of access based on access rights.
+
+**3.1.4 availability** [b-ITU-T X.800]: The property of being accessible and useable upon demand by an authorized entity.
+
+**3.1.5 confidentiality** [b-ITU-T X.800]: The property that information is not made available or disclosed to unauthorized individuals, entities, or processes.
+
+**3.1.6 data integrity** [b-ITU-T X.800]: The property that data has not been altered or destroyed in an unauthorized manner.
+
+**3.1.7 firewall** [b-ISO/IEC 27033-1]: Type of security barrier placed between network environments – consisting of a dedicated device or a composite of several components and techniques – through which all traffic from one network environment traverses to another, and vice versa, and only authorized traffic, as defined by the local security policy, is allowed to pass.
+
+**3.1.8 intrusion detection** [b-ISO/IEC 27039]: Formal process of detecting intrusions, generally characterized by gathering knowledge about abnormal usage patterns, as well as what, how, and which vulnerability has been exploited to include how and when it occurred.
+
+**3.1.9 intrusion detection system** [b-ISO/IEC 27039]: Information systems used to identify that an intrusion has been attempted, is occurring, or has occurred.
+
+**3.1.10 intrusion prevention system** [b-ISO/IEC 27039]: Variant on intrusion detection systems that are specifically designed to provide an active response capability.
+
+**3.1.11 privacy** [b-ITU-T-X.800]: The right of individuals to control or influence what information related to them may be collected and stored and by whom and to whom that information may be disclosed.
+
+NOTE – Because this term relates to the right of individuals, it cannot be very precise and its use should be avoided except as a motivation for requiring security.
+
+**3.1.12 security gateway** [b-ISO/IEC 27033-1]: Point of connection between networks, or between subgroups within networks, or between software applications within different security domains intended to protect a network according to a given security policy.
+
+**3.1.13 repudiation** [b-ITU-T X.800]: Denial by one of the entities involved in a communication of having participated in all or part of the communication.
+
+**3.1.14 threat** [b-ISO/IEC 27000]: Potential cause of an unwanted incident, which may result in harm to a system or organization.
+
+### **3.2 Terms defined in this Recommendation**
+
+None.
+
+# **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|       |                                                          |
+|-------|----------------------------------------------------------|
+| 2FA   | Two-Factor Authentication                                |
+| ACL   | Access Control Lists                                     |
+| AES   | Advanced Encryption Standard                             |
+| ATM   | Automatic Teller Machine                                 |
+| CEO   | Chief Executive Officer                                  |
+| DDoS  | Distributed Denial of Service                            |
+| DHCP  | Dynamic Host Configuration Protocol                      |
+| DMZ   | Demilitarized Zone                                       |
+| FTP   | File Transfer Protocol                                   |
+| GGSN  | Gateway General packet radio service (GPRS) Support Node |
+| GPRS  | General Packet Radio Service                             |
+| HIDS  | Host Based Intrusion Detection System                    |
+| HTTP  | Hypertext Transport Protocol                             |
+| HTTPS | Hypertext Transport Protocol Secure                      |
+| ICT   | Information Communication Technology                     |
+| IDPS  | Intrusion Detection and Prevention System                |
+
+|       |                                     |
+|-------|-------------------------------------|
+| IDS   | Intrusion Detection System          |
+| IP    | Internet Protocol                   |
+| IPS   | Intrusion Prevention Systems        |
+| IPSec | Internet Protocol Security          |
+| IPSG  | IP Source Guard                     |
+| ISP   | Internet Service Provider           |
+| MFA   | Multi-Factor Authentication         |
+| NIDS  | Network Based Intrusion System      |
+| OS    | Operating system                    |
+| OSI   | Open System Interconnection         |
+| PC    | Personal Computer                   |
+| PII   | Personally Identifiable Information |
+| PIN   | Personal Identification Number      |
+| RPC   | Remote Procedure Call               |
+| SFA   | Single Factor Authentication        |
+| SGSN  | Serving GPRS Support Node           |
+| SMB   | Server Message Block                |
+| SNMP  | Simple Network Management Protocol  |
+| TFA   | Three-Factor Authentication         |
+| TLS   | Transport Layer Security            |
+| VPN   | Virtual Private Network             |
+
+# **5 Conventions**
+
+None.
+
+# **6 Overview of information security measures**
+
+A security measures is a means of managing risk, and includes policies, procedures, guidelines, practices or organisational structures, which can be of an administrative, technical, management, or legal nature.
+
+A security dimension is a set of security measures designed to address a particular aspect of the network security. The security dimensions, defined in [ITU-T X.805] are:
+
+- access control;
+- authentication;
+- non-repudiation;
+- data confidentiality;
+- communication security;
+- data integrity;
+- availability; and
+- privacy.
+
+A set of technical implementation guidance for each dimension should be defined and implemented by organizations.
+
+This Recommendation presents a technical implementation guideline, which provides a set of security measures for each dimension, for mitigating the most common threats.
+
+Deploying these security measures can assist an organisation in protecting against the most common forms of cyber-attack emanating from the external network.
+
+Organisations implementing these security measures can benefit by gaining confidence that basic technical security measures are in place and that important steps are being taken to protect its information and system. The technical implementation guidance can be used to:
+
+- improve organizations' security capabilities and posture;
+- allow organizations to effectively and consistently evaluate security capabilities;
+- share knowledge, best practices, and relevant documents across organizations as a means to improve security capabilities; and
+- allow organizations to prioritize security measures and their associated activities and investment resources to improve security.
+
+# **7 Information security measures**
+
+### **7.1 Access control**
+
+Access control protects against unauthorized use of network resources. User accounts, particularly those with special access privileges (e.g., administrative accounts) should be assigned only to authorized individuals, managed effectively and provide the minimum level of access to applications, computers and networks. User accounts should be managed through robust access control. The following information security measures should be considered regarding access control:
+
+- Organizations should create user account according to a provisioning and approval process.
+- Organization should allow special access privileges to a limited number of authorized individuals.
+- Organizations should document details about special access privileges (e.g., the individual and purpose), keep them in a secure location and review them on a regular basis (e.g., quarterly).
+- Organizations should use administrative accounts to perform authorized administrative activities, and should not grant access to the Internet.
+- Organization should change password for administrative accounts on a regular basis (e.g., at least every 60 days).
+- Organization should allow each user to be authenticated using a unique username and strong password before being granted access to applications, computers and network devices.
+- Organizations should remove or disable user accounts and special access privileges when no longer required (e.g., when an individual changes role or leaves the organization) or after a pre-defined period of inactivity (e.g., 3 months).
+
+### **7.2 Authentication**
+
+The authentication serves to confirm the identities of communicating entities. There are three types of authentication factors:
+
+- knowledge factor ("something only a user knows"), such as passwords;
+- possession factor ("something only a user has"), such as automatic teller machine (ATM) cards; and
+
+- inherence factor ("something only a user is"), such as biometrics.
+
+There are three types of authentication methods described in [b-ITU-T X.1158]:
+
+- Single-factor authentication (SFA) is the traditional one that requires only a user name and password before granting access to the user.
+- Two-factor authentication – Two-factor authentication (also known as 2FA) is based on using the combination of two different authentication factors. These factors may be something that a user knows, something that a user has or something that a user is. A good example in everyday life is that when a user wants to withdraw money from a cash machine, only the correct combination of a bank card (something that a user has) and a personal identification number (PIN), i.e., something that a user knows) allows the transaction to be conducted.
+- Three-factor authentication (TFA) is based on using the combination of three different independent factors: what a user knows (password), what a user has (security token) and what a user is (biometric verification).
+
+Multi-factor authentication (MFA) is based on using the combination of two or more independent different factors. Two-factor authentication and three-factor authentication are a part of multi-factor authentication.
+
+The organizations should determine the authentication methods based on the result of risk assessment. User authentication should be managed through robust authentication. Organizations should consider the following information security measures regarding authentication:
+
+- Organizations should use the methods of authentication which is appropriate for the classification of the information to be accessed.
+- Organizations should employ a strong authentication method such as two-factor or three-factor authentication (identity/password, one-time password, public-key certificate) when using privileged access right to information system and applications as an administrator.
+- Organizations should provision identities for personnel and other entities (e.g., services, devices) who require access to assets (note that this does not preclude shared identities).
+- Organizations should issue credentials for personnel and other entities that require access to assets (e.g., passwords, smart cards, certificates, keys).
+- Organizations should de-provision identities when no longer required.
+- Organizations should periodically review and update identity repositories to ensure validity (i.e., to ensure that the identities still need access).
+- Organizations should periodically review credentials to ensure that they are associated with the correct person or entity.
+- Organizations should de-provision identities within organizationally defined time thresholds when no longer required.
+- Organizations should inform employees of requirements for credentials according to the organization's risk criteria (e.g., multifactor credentials for higher risk access).
+
+### **7.3 Non-repudiation**
+
+The non-repudiation provides means for preventing an individual or entity from denying having performed a particular action related to data by making available proof of various network-related actions (such as proof of obligation, intent, or commitment; proof of data origin, proof of ownership, proof of resource use). Organizations should consider the following information security measures regarding non-repudiation:
+
+- Organizations should incorporate procedures to ensure non-repudiation.
+- Organizations should implement appropriate measures such as using digital signature to guard against later denial that they furnished the signature.
+
+- Organizations should use technical mechanisms for non-repudiation in [b-ITU-T X.813].
+- Organizations should use cryptographic techniques to support non-repudiation and to provide evidence of the occurrence or non-occurrence of an event or action.
+
+In addition, the implementation guidance for cryptography from [b-ITU-T X.1051] clause 10 could also be considered.
+
+### **7.4 Data confidentiality**
+
+The data confidentiality protects data from unauthorized disclosure. Sensitive information in transit or at rest should be protected by appropriate measures. Organizations should consider the following information security measures regarding data confidentiality:
+
+- Organizations should implement appropriate measures such as cryptographic technologies and data leakage prevention technologies to prevent unauthorized disclosure of sensitive personal data at rest or in transit.
+- Organization should incorporate procedures to ensure data confidentiality.
+- Organizations should use technical mechanisms for data confidentiality in [b-ITU-T X.814].
+- In addition, the implementation guidance from [b-ITU-T X.1051] clause 10 could also be considered.
+
+### **7.5 Communication security**
+
+Information, applications and computers within the organization's internal networks should be protected against unauthorized access and disclosure from the internet, using boundary firewalls, internet gateways or equivalent network devices.
+
+The communication ensures that information flows only between the authorized end points (the information is not diverted or intercepted as it flows between these end points).
+
+#### **7.5.1 Security gateway**
+
+A security gateway is placed at the boundary between two network segments, for example, between the organization's internal network and a public network, to filter the traffic flowing across the boundary in accordance with the documented security gateway service access policy for that boundary.
+
+#### **7.5.2 Firewall**
+
+The firewall is a typical implementation of the security gateway that controls the incoming and outgoing network traffic based on an applied rule set. A firewall establishes a barrier between a trusted, secure internal network and another external network (e.g., the Internet) that is assumed not to be secure and trusted. There are two types of firewalls: software-based firewall which is implemented as software to run on general purpose hardware and a hardware-based firewall which exists as hardware appliance. Many hardware-based firewalls also offer other functionality to the internal network they protect, such as acting as a dynamic host configuration protocol (DHCP) server for that network.
+
+#### **7.5.3 Intrusion detection system**
+
+An intrusion detection system (IDS) is a device or software application that monitors network or system activities for malicious activities or policy violations and produces reports to a management station. There are two types of IDS: network based intrusion system (NIDS) and host based intrusion detection systems (HIDS).
+
+#### **7.5.4 Intrusion prevention system**
+
+Intrusion prevention systems (IPS), also known as intrusion detection and prevention systems (IDPS), are network security appliances that monitor network and/or system activities for malicious activity. The main functions of intrusion prevention systems are to identify malicious activity, log information about this activity, attempt to block/stop it, and report it. Intrusion prevention systems are considered extensions of intrusion detection systems because they both monitor network traffic and/or system activities for malicious activity. The main differences are, unlike intrusion detection systems, intrusion prevention systems that are placed in-line and are able to actively prevent/block intrusions that are detected.
+
+#### **7.5.5 Application firewall**
+
+An application firewall is a form of firewall which controls input, output, and/or access from, to, or by an application or service. It operates by monitoring and potentially blocking the input, output, or system service calls which do not meet the configured policy of the firewall. The application firewall is typically built to control all network traffic on any open system interconnection (OSI) layer up to the application layer. It is able to control applications or services specifically, unlike a stateful network firewall which is – without additional software – unable to control network traffic regarding a specific application.
+
+#### **7.5.6 Technical implementation guidance**
+
+End points, such as personal computers and notebook computers that are able to access external network and communicate through the wireless access point should be assigned in order to protect unauthorized access from attacks outside.
+
+When wireless access points are deployed, security mechanisms (i.e., Wi-Fi Protected Access II [b-Wi-Fi]) should be used in order to protect communications between the access point and mobile station.
+
+Public network access from personal computers that are able to access the information systems dealing with processing massive personally identifiable information (PII) should be prohibited.
+
+Internal network should be segregated via a firewall to protect internal operation network from attacks outside. Public server such as web server should exist in the demilitarized zone which exists between the internal operation network and external network.
+
+Unauthorized use of wireless access point should be detected and unauthorized access to the internal information system through the wireless access point protected.
+
+One or more firewalls (or equivalent network device) should be installed on the boundary of the organisation's internal network(s). As a minimum:
+
+- The default administrative password for any firewall (or equivalent network device) should be changed to an alternative, strong password.
+- Each rule that allows network traffic to pass through the firewall (e.g., each service on a computer that is accessible through the boundary firewall) should be subject to approval by an authorised individual and documented (including an explanation of business need).
+- Unapproved services, or services that are typically vulnerable to attack (such as server message block (SMB), NetBIOS, tftp, remote procedure call (RPC), rlogin, rsh or rexec), should be disabled (blocked) at the boundary firewall by default.
+- Firewall rules that are no longer required (e.g., because a service is no longer required) should be removed or disabled in a timely manner.
+- The administrative interface used to manage boundary firewall configuration should not be accessible from the Internet.
+
+Organizations should install one or more firewalls, intrusion detection systems, application firewall on the boundary of and within the organization's internal network(s) according to risk assessment result. In addition,
+
+- organization should operate network access control functions for end points, such as desktop PC and notebook computers, which can access wireless access point or/and the internal wired network to prevent unauthorized access to the internal network;
+- when using wireless access point, organization should have secure access point configuration in place, for example, use of secure transfer mode;
+- organization should prevent remote access to information system which processes massive amount of PII, for example, to a database containing user's ID and password;
+- organization should operate demilitarized zone (DMZ) to separate internal network with external network and operate public server such as web server in DMZ area;
+- organization should operate the wireless intrusion detection system which can detect and prevent any unauthorized use of wireless access points.
+
+### **7.6 Data integrity**
+
+Data integrity ensures the correctness or accuracy of data, and protects against improper information modification or destruction. It includes ensuring information non-repudiation and authenticity. For an asset, integrity is the quality of being in the condition intended by the owner and therefore continuing to be useful for the purposes intended by the owner. Organizations should consider the following information security measures regarding data integrity:
+
+- Organization should evaluate suggested changes to inventoried assets before applying them.
+- Organization should log changes to inventoried assets.
+- Organization should test changes to assets prior to its deployment, whenever possible.
+- Change management practices address the full life cycle of assets (i.e., acquisition, deployment, operation, retirement).
+- Organization should test changes to assets for security impact prior to deployment.
+- Change logs include information about modifications that impact the security requirements of assets (availability, integrity, confidentiality).
+
+### **7.7 Availability**
+
+Availability ensures that there is no denial of authorized access to network elements, stored information, information flows, services and applications due to events impacting the network.
+
+One of the typical attacks which compromise network availability is a distributed denial of service (DDoS) attack which is an attempt to make an online service unavailable by overwhelming it with massive amount of traffic from multiple sources.
+
+DDoS mitigation system is a hardware that includes purpose-built automated network devices for detecting and mitigating some levels of DDoS attacks. Sometimes perimeter security hardware such as firewalls and intrusion detection systems (IDS) may include features intended to address some types of small DDoS attacks. DDoS mitigation system performs three basic functionalities as follows:
+
+- mitigating DDoS attack, not just detecting;
+- distinguishing good traffic from bad traffic to preserve business continuity, not just detecting the overall presence of an attack;
+- maintaining reliable and cost-efficient scalability.
+
+A DDoS protection system provided additional protection functionalities as follows:
+
+- enables immediate response to DDoS attacks through integrated detection and blocking mechanisms, even during spoofed attacks when attacker identities and profiles are changing constantly;
+- provides more complete verification capabilities than either static router filters or IDS signatures can provide to date;
+- delivers behaviour-based anomaly recognition to detect valid packets sent with malicious intents to flood a service;
+- identifies and blocks individual spoofed packets to protect legitimate business transactions;
+- offers mechanisms designed to handle the huge volume of DDoS attacks without suffering the same fate as protected resources;
+- enables timely deployment to protect the network during attacks without introducing a point of failure;
+- processes (with built-in intelligence) only contaminated traffic streams, helping ensure maximum reliability and minimum scaling costs;
+- avoids reliance on network device resources or configuration changes;
+- uses standard protocols for all communications, helping ensure maximum interoperability and reliability.
+
+Organizations should install DDoS protection system on the boundary of and within the organization's internal network(s) according to risk assessment result. To this end:
+
+- Organizations could have a capability to use DDoS protection service provided by the Internet service provider (ISP).
+- Organizations should deploy a DDoS protection system on the boundary of and within the organization's internal network(s).
+
+### 7.8 Privacy
+
+The privacy security dimension provides for the protection of information that might be derived from the observation of network activities.
+
+- Appropriate measures should be implemented to protect personally identifiable information processed.
+
+Additional ISO/IEC guidance for the protection of PII can be found in [b-ISO/IEC 29100]. [b-ISO/IEC 29100] describes basic privacy requirements in terms of three main factors: (1) legal and regulatory requirements for the safeguarding of the individual's privacy and the protection of his/her PII, (2) the particular business and use case requirements, and (3) individual privacy preferences of the PII entity. [b-ISO/IEC 29100] describes the following basic privacy principles: consent and choice, purpose specification, collection limitation, use, retention and disclosure limitation, data minimization, accuracy and quality openness, transparency and notice, individual participation and access, accountability, security controls and compliance.
+
+# **Annex A**
+
+## **Additional technical implementation guidance**
+
+(This annex forms an integral part of this Recommendation.)
+
+This annex provides additional implementation guidance to implement [ITU-T X.805] security domains.
+
+### **A.1 Secure configuration**
+
+Configuration management is the task of tracking and controlling changes in the software.
+
+Computers and network devices should be configured to reduce the level of inherent vulnerabilities and provide only the services required to fulfil their role. Computers and network devices (including wireless access points) should be securely configured. To this end:
+
+- Organizations should remove and disable unnecessary user accounts (e.g., guest accounts and unnecessary administrative accounts).
+- Organizations should change any default password for a user account to an alternative, strong password.
+- Organizations should remove or disable unnecessary software (including application, system utilities and network services).
+- Organizations should disable the auto-run feature to prevent software programs running automatically when removable storage media is connected to a computer or when network folders are accessed.
+- Organizations should enable a personal firewall (or equivalent) on desktop personal computers (PCs) and laptops, and configured to disable (block) unapproved connections by default.
+
+### **A.2 Malware protection**
+
+Malware (short for malicious software) is software designed to infiltrate or damage a computer without user's consent. Malware includes computer viruses, worms, Trojan horses, spyware, scareware and more. It can be present on websites and emails or hidden in downloadable files, photos, videos, freeware or shareware. (However, it should be noted that most websites, shareware or freeware applications do not come with malware.)
+
+The best way to avoid getting infected is to run a good anti-virus protection program, do periodic scans for spyware, avoid clicking on suspicious e-mail links or websites. But scammers are sneaky: sometimes malware is cleverly disguised as an email from a friend, or a useful website.
+
+Computers that are exposed to the internet should be protected against malware infection through the use of malware protection software. The organization should implement robust malware protection on exposed computers. To this end:
+
+- Organizations should install malware protection software on all computers that are connected to or capable of connecting to the Internet.
+- Organizations should keep malware protection software (including program code and malware signature files) up-to-date (e.g., at least daily, either by configuring it to update automatically or through the use of centrally managed deployment).
+- Organizations should configure malware protection software to scan files automatically upon access (including when downloading and opening files, accessing files on removable storage media or a network folder) and scan web pages when being accessed (via a web browser).
+
+- Organizations should configure malware protection software to perform regular scans of all files (e.g., daily).
+- Organizations should install malware protection software to prevent connections to malicious websites on the internet (e.g., by using website blacklisting).
+
+### **A.3 Patch management**
+
+A patch is a piece of software designed to update a computer program or its supporting data, to fix or improve it. Patch management is the process of using a strategy and plan of what patches should be applied to which systems at a specified time.
+
+Software running on computers and network devices should be kept up-to-date and have the latest security patches installed. Software should be kept up-to-date, and to this end:
+
+- Organizations should have a license for software running on computers and network devices that are connected to or capable of connecting to the internet (by the software vendor or supplier of the software) to ensure security patches for known vulnerabilities are made available.
+- Organizations should install updates to software (including operating system software and firmware) running on computers and network devices that are connected to or capable of connecting to the internet in a timely manner (e.g., within 30 days of release or automatically when they become available from vendors).
+- Organizations should remove out-of-date software (i.e., software that is no longer supported) from computer and network devices that are connected to or capable of connecting to the Internet.
+- Organizations should install all security patches for software running on computers and network devices that are connected to or capable of connecting to the Internet in a timely manner (e.g., within 14 days of release or automatically when they become available from vendors).
+
+### **A.4 Vulnerability management**
+
+Vulnerability management is the practice and procedure of identifying, classifying, remediating, and mitigating vulnerabilities. To this end:
+
+- Organizations should establish a vulnerability management plan, including identifying information assets for personnel in charge of monitoring cycle and target systems, and the methodology for the vulnerability management.
+- Organizations should conduct vulnerability monitoring against information systems and services that an organization manage.
+- The vulnerability monitoring results should be reported to the personnel who are in charge of security in an organization.
+- The competent personnel in an organization should conduct vulnerability monitoring.
+- Vulnerability monitoring for critical information asset such as web servers and information systems processing PII should be carried out at least two times per year.
+- Timely remedy should be taken and remedy result should be reported to the personnel who is in charge of information security.
+
+### **A.5 Information security incidents management**
+
+This security measure ensures information security events and vulnerabilities associated with the organization's information and information system assets are communicated in a manner to allow appropriate corrective actions to be taken.
+
+Managing incidents effectively involves detective and corrective security measures designed to minimize adverse impacts, gather forensic evidence (where applicable) and learn the lessons in terms of the implementation of more effective preventive measures. To this end:
+
+- Organizations should operate information systems for detecting incidents and maintain the event records.
+- Organizations should establish management framework and document roles and responsibilities for and process and procedures of the incident management, and maintain point of contacts for the incident management in an organization.
+- Organizations should conduct continuous, consistent monitoring to prevent sensitive data leakage incident and systems being hacked.
+- Organization should have appropriate incident corrective actions in place according to the nature of incidents.
+- Organization should conduct training and testing to verify the effectiveness of incident response systems at least one time every year and provide the report to the personnel in charge of information security on any necessary actions and remedies for mitigating the occurrence of incidents.
+
+### **A.6 System development security**
+
+Secure development is a requirement to build up a secure service, architecture, software and system. To this end:
+
+- Organizations should identify security requirements, such as compliance requirements (i.e., encryption requirement) and apply them to any information system development efforts.
+- Organizations should ensure that software developers complete training and education programme, for example on secure coding technology, or use monitoring tool to check if secure coding techniques are applied.
+- Organizations should conduct vulnerability monitoring for the software that has been developed and have remedy actions in place for identified vulnerabilities, if necessary, prior to deploying it in a real operating environment.
+- Organizations should separate the operation server from the server for development and testing data should be used when testing the server.
+
+### **A.7 Authentication for information systems and applications**
+
+Procedures should be established to ensure strong authentication for information systems and applications. To this end:
+
+- User authentication management should use secure password in terms of strength and length when users and/or administrator access information systems and applications.
+- Organizations should have the security policy and procedures in place, concerning identification and authentication to information systems and applications.
+- Organizations should check if authentication practice meets requirements according to security policy and guidance.
+- Organizations should grant access privilege to information systems and applications only to the administrator according to their authorization procedure.
+- Organizations should employ strong authentication method, for example multi-factor authentication such as combined use of the one-time password and public-key certificate when administrator's privilege are used to access information system and applications.
+
+### **A.8 Data leakage prevention**
+
+Procedures should be established to ensure prevention of data leakage in an organization. To this end:
+
+- Organizations should encrypt sensitive information in transit and at rest according to organizational policy.
+- Organizations should have data leakage prevention system in place to prevent unauthorized disclosure of data through the use of portable media and removable media.
+- Organizations should have security system in place to detect and prevent unauthorized leakage of sensitive data by insiders.
+- Organizations should analyse log information recorded by the information security gateway and database to detect and prevent data leakage in advance.
+
+### **A.9 Operations security**
+
+Secure operations of information processing facilities should be ensured. To this end:
+
+- Organizations should implement malware protection measures: anti-virus program installation, patching of vulnerable system, and blocking remote use and access to internal information systems.
+- Organizations should establish the procedure for assigning administrator for information systems and managing policy update, ruleset change, and events monitoring of information systems according to type and nature of information systems.
+- Organizations should produce event logging recordings and keep (at least 6 months) and review regularly them.
+- Organizations should establish and implement procedures for managing information systems and services operations (i.e., management for configuration change, acquisition, performance monitoring and recovery procedure from failure event).
+
+Organizations should ensure security of teleworking.
+
+### **A.10 Backup and disaster recovery**
+
+Procedures for backup and disaster recovery should be established to protect loss of data. To this end:
+
+- Organizations should establish policy for backup and recovery, define requirements of backup of information, software and systems to ensure integrity and availability of information assets, and conduct backup procedure periodically according to organization's backup policy.
+- Organizations should provide appropriate level of physical and environmental protection of critical backup information i.e., a secure place to prevent physically unauthorized access and environmental threats.
+- Organizations should maintain real-time backup system and store the backup information in a remote location, at a sufficient distance to escape any damage from a disaster at the main site.
+- Organizations should conduct disaster recovery training regularly (at least one time per year) using backup information.
+
+### **A.11 Desktop PC and mobile device protection**
+
+Desktop PC should be protected by appropriate security measures. When using mobile devices, organizations should take special care to ensure that business information is not compromised data. To this end:
+
+- Organizations should define and disseminate security guidance of desktop PCs to support user's self-assessment.
+
+- Organizations should periodically monitor the effectiveness of security measures against the desktop PC for business (i.e., anti-virus program installation and update configuration, security patch for operating systems and removing shared directory).
+- Organizations should establish and operate centralized management system to apply security measures in a centrally controlled manner against PCs in a business environment.
+- Organizations should establish and implement security practices for use of mobile device (notebook, smart device, smart phones, and smart pad) in business.
+
+## Appendix I
+
+## Organizational implementation guidance
+
+(This appendix does not form an integral part of this Recommendation.)
+
+This appendix provides additional organizational implementation guidance that an organization can consider.
+
+### I.1 Information security policies
+
+A set of operational policies should be defined, approved by management, published and communicated to employees and relevant external parties. In this regard:
+
+- Organizations should document operational policies including management commitment to operational policies, compliance to relevant laws/regulations.
+- Organizations should publish operational policies, approved by management, which are easily accessible by all employees.
+- Organizations should review the operational policies periodically on a regular basis to take into account updates of laws/regulations.
+- Organizations should put disciplinary measures in place to address employees breaching the operational policies.
+
+The organization's approach to managing information security and its implementation should be reviewed independently at planned intervals or when significant changes occur.
+
+- The individual in charge of information security in top management should review implementation of security measures at least once per year to ensure that all activities relevant to information security are properly maintained.
+- Organizations should establish the review of implementation including review team, timeline for review, scope of implementation, and items to be reviewed.
+- The review results should be reported to management including the chief executive officer (CEO) and communicated to relevant employees for corrective actions.
+- The review should be conducted by an independent and competent team.
+
+### I.2 Organization of information security
+
+- Organizations should identify and set up the following tasks:
+  - roles and responsibilities;
+  - relevant laws and regulations;
+  - security objectives and assets to be protected;
+  - resource (budget, human) plan.
+- An organization should appoint an individual in charge of information security in top management to ensure that assets and technologies are adequately protected.
+- The individual in charge of information security in top management security measures should be competent and have the appropriate education, training, and experience to perform information security.
+- The information security organization should periodically report information security activities to the individual in charge of information security in top management.
+
+Annual information security plan should be established.
+
+- Organizations should establish the annual information security controls to address risks in an annual information security plan.
+
+- Organizations should document an annual information security plan including scope to be protected, owner of controls, control objectives, and implementation timeline.
+- Organizations should obtain approval of the information security plan from the individual responsible for implementing security measures.
+- Implementation of the information security plan should be reviewed by the individual responsible for implementing security measures.
+
+The organization should have budget to implement the controls.
+
+- Organizations should establish and document the information security budget plan, obtain approval of this budget plan from the top management.
+- Organizations should assign and invest at least a certain ratio of budget of information security to that of information communication technology (ICT).
+- Organizations should evaluate and audit the implementation of the budget plan periodically.
+
+The organization should provide dedicated resources needed for the establishment, implementation, maintenance and continual improvement of the information security.
+
+- Organizations should assign information security staff who are in charge of operation of information security and document their roles and responsibilities.
+- Organizations should engage information security staff with a number of years of experience, a certain degree of education, and certifications relevant to information security.
+- Information security staff should take training courses for at least the number of hours per year specified in the information policy.
+- Organizations should have dedicated information security staff.
+
+The organization should perform internal and external communications regarding the information security as follows:
+
+- Organizations should periodically provide the CEO with the necessary information relevant to information security (for example, newsletter, best practices, implementation guidance etc.).
+- Organizations should inform external parties of any updates of technologies and regulations at least once per year.
+- Organizations should conduct periodic internal briefings with information security staff.
+- Organizations should have a periodic internal meeting with the participation of the CEO, the individual responsible for implementing security measures, and relevant employees to determine the information security policy.
+
+### **I.3 Human resources security**
+
+Organizations should conduct human resources security during the whole life cycle of employment: prior to employment, during employment and termination of employment. To facilitate the human resources security process:
+
+- Organizations should obtain from the employee, prior to employment, information security related agreement including confidential and non-disclosure, legal responsibilities and rights, disciplinary actions in case of a breach of the information security policies.
+- Organizations should obtain separate information security pledge agreement including confidential and non-disclosure, legal responsibilities and rights, disciplinary actions when breaching the information security policies from employee on termination of employment.
+- Organizations should withdraw as soon as possible (at least within five days) access right to the information system, and restrict operation rooms to staff that terminates or changes employment.
+
+All employees and contractors should receive appropriate awareness education and training along the following guidelines:
+
+- Organizations should establish the annual education and training plan and conduct them at planned intervals.
+- Organizations should conduct education and training for all staff and contractors.
+- Organizations should conduct education and training of the staff of the organization and contractors dedicated to specific roles.
+- Organizations should submit a report related to the education and training to management including the individual responsible for implementing security measures with the feedback result from trainees, participation rates and corrective actions.
+- Organizations can encourage participation in education and training.
+- Organization should establish and provide information security awareness program to the staff that has access right to the critical information system and PII processing system requesting employees to comply with the information security policies of an organization.
+
+### **I.4 Asset management**
+
+Assets should be identified and an inventory of these assets should be systematically maintained and to this end:
+
+- Organizations should identify, document and keep up-to-date an inventory of assets.
+- Organizations should classify information in terms of legal requirements, value, criticality and sensitivity to unauthorized disclosure or modification.
+- Organizations should maintain a log to record the change or modification of assets.
+- Organizations should check on a regular basis consistency of assets (for example asset owner, Internet protocol (IP) address, physical deployment location, administrator) against the inventory of assets.
+
+### **I.5 Physical and environment security**
+
+Organizations should prevent unauthorized physical access, damage and interference to the organization's information and information processing facilities. In order to guarantee physical and environment security:
+
+- Organizations should provide secure areas to guard either sensitive or critical information and information processing facilities.
+- Organizations should apply the necessary physical protection facilities (for example, the fire extinguisher) to protect against natural disasters, malicious attack or accidents.
+- Organizations should apply (for example, the emergence power supplier and uninterruptable power supply) to protect from power failures and other disruptions caused by failures in supporting utilities.
+- Organizations should operate supporting utilities (for example, air conditioning, sewage and ventilation) for stable operation of information processing system.
+
+Organizations should ensure that only authorized personnel be allowed access to the secure area that contains both sensitive or critical information and information processing facilities. In order to ensure this:
+
+- Organizations should operate physical entry control to secure areas to ensure that only authorized personnel is allowed access and record the data and time of entry and departure of visitor.
+- Organizations should perform physical entry control for visitors to secure areas: the identity of visitors should be registered and authenticated by an appropriate means, the internal
+
+personnel should accompany visitors, and physically separated visitor's reception room should be provided outside secure areas.
+
+- Organizations should record and monitor all entries and departures of visitors to secure areas and all activities of visitors in the secure area by some monitoring facilities.
+- Organizations should register incoming materials (for example, notebook computers, computing facilities, removable media, smart devices in accordance with asset management policies on entry to the site and inspected incoming materials for evidence of tampering en route.
+
+Organizations should ensure physical security for offices and rooms. To this end:
+
+- Organizations should put in place measures, e.g., paper shredders, to destroy sensitive and confidential documents and provide a cabinet to store sensitive documents.
+- Organizations should establish the office security policy for entry control and secure document management and review implementation of this policy on a monthly basis.
+- Organizations should apply an entry control to the secure document storage and secure office and rooms to ensure that only authorized personnel is allowed access to them.
+- Organizations should apply a physical access control to the office machines (for example, facsimile, copy machine and scanner) to ensure that only authorized personnel is allowed access.
+
+### **I.6 Supplier relationship**
+
+Organizations should conduct supplier relationships' security measures as follows:
+
+- Organizations should obtain information security pledge agreement from the employee of contractors, who has access right to the critical information system and PII processing system.
+- Organizations should establish information security terms in an agreement and contracts for inclusion: the purpose and scope of each supplier, obligation of each contractual party to implement an agreed set of controls, relevant regulations for sub-contracting, right to audit the supplier processes and controls related to the agreement, supplier's obligation to periodically deliver an independent report on the effectiveness of controls, legal and regulatory requirements.
+- Organizations should evaluate the implementation of information security controls when contractors terminates the supplier relationship: safe return of assets provided, complete destruction of sensitive information, and non-disclosure of information acquired during being outsourced.
+- Organizations should establish and implement information security policy for supplier relationships including identifying management owner, procedure and process for managing information security policy for supplier relationships.
+- Organizations should identify and put in place information security requirements and perform regular evaluation to audit the compliance of the supplier processes and controls with the agreement or contract.
+
+Further implementation guidance is provided in [b-ITU-T X.1051].
+
+# Appendix II
+
+## Level of security assurance
+
+(This appendix does not form an integral part of this Recommendation.)
+
+This appendix provides typical examples of level of assurance related to the security.
+
+### II.1 Level of assurance for entity authentication [b-ITU-T X.1254]
+
+This entity authentication assurance framework in [b-ITU-T X.1254] defines four levels of assurance (LoA) for entity authentication.
+
+### II.2 Level of security assurance
+
+This appendix presents the example of five levels of security assurance (LoA) in an organization as shown in Table II.1.
+
+**Table II.1 – Level of security assurance [b-SECU]**
+
+| Level             | Description                                                                                                                                                                                                                                                                                    |
+|-------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 1-limited (B)     | Organizational security practices are not formalized, and risk is not managed.                                                                                                                                                                                                                 |
+| 2-partial (BB)    | Organizational security practices are not formalized, and risk is managed in an ad hoc and sometimes reactive manner.                                                                                                                                                                          |
+| 3-medium (A)      | Risk management practices are approved by management but may not be established as organizational-wide policy.                                                                                                                                                                                 |
+| 4-repeatable (AA) | The organization's security practices are formally approved and expressed as policy. Organizational security practices are regularly updated based on the application of risk management processes to changes in business/mission requirements and a changing threat and technology landscape. |
+| 5-adaptable (AAA) | The organization adapts its security practices based on lessons learned and predictive indicators derived from previous and current cybersecurity activities.                                                                                                                                  |
+
+# Appendix III
+
+## Guidance on assigning specific level of security assurance from the final index
+
+(This appendix does not form an integral part of this Recommendation.)
+
+### III.1 Methodology for level of security assurance
+
+This appendix suggests how to calculate the level of security assurance. The following steps apply:
+
+- Select all indicators (that are of interest to an organization) in the technical implementation guidance (in clause 7, Annex A, Appendix I).
+- Determine sub-indices from indicators, depending on their nature.
+- Determine the weight for indicators and sub-indices.
+- Calculate the value of weighted indicators and sub-indices.
+- Calculate the final value by summing up the weighted indicators.
+- Assign the specific level of security assurance according to final values (see Table III.1 for example).
+
+This appendix provides an example about level of security assurance from the final index values.
+
+**Table III.1 – Level of security assurance [b-SECU]**
+
+| Level of security assurance | Final assurance value                                                                       |
+|-----------------------------|---------------------------------------------------------------------------------------------|
+| 1-limited (B)               | $B_{\min}(\text{for example, } 0.23) \geq \text{and} > B_{\max}(\text{for example, } 0.4)$  |
+| 2-partial (BB)              | $BB_{\min}(\text{for example, } 0.4) \geq \text{and} > BB_{\min}(\text{for example, } 0.6)$ |
+| 3-medium (A)                | $A_{\min}(\text{for example, } 0.6) \geq \text{and} > A_{\min}(\text{for example, } 0.8)$   |
+| 4-repeatable (AA)           | $AA_{\min}(\text{for example, } 0.8) \geq \text{and} > AA_{\min}(\text{for example, } 0.9)$ |
+| 5-adaptable (AAA)           | $\geq AAAA_{\min}(\text{for example, } 0.9)$                                                |
+
+The parameters in Table III.1 should be determined according to security policies in an organization.
+
+# Appendix IV
+
+## SGSN specific implementation guideline
+
+(This appendix does not form an integral part of this Recommendation.)
+
+This appendix provides implementation guidance for SGSN (Serving GPRS Support Node) based on security dimension described in [ITU-T X.805] security dimension.
+
+### IV.1 Overview
+
+General packet radio service (GPRS) is based on IP. The serving GPRS support node (SGSN) is a main component of the GPRS network, which deals with all packet switched data within the network. Table IV.1 provides an [ITU-T X.805] security architecture.
+
+**Table IV.1 – Security architecture**
+
+|                         | Infrastructure layer | Services layer | Application layer |
+|-------------------------|----------------------|----------------|-------------------|
+| <b>End user plane</b>   | Module 3             | Module 6       | Module 9          |
+| <b>Control plane</b>    | Module 2             | Module 5       | Module 8          |
+| <b>Management plane</b> | Module 1             | Module 4       | Module 7          |
+
+The infrastructure layer refers to components that are individual network elements (i.e., SGSN) as well as the communication links between them. The management plane is concerned with operations, administration, maintenance and provisioning (OAM&P) activities such as provisioning a user or network elements.
+
+### IV.2 Access control dimension for module 1
+
+The access control dimension protects against unauthorized access of network elements and ensures that only authorized personnel or devices are allowed access network elements. The following measures should be ensured:
+
+- Management access user restriction: SGSN is provided with role-based access control (RBAC) which provides different access levels to guarantee that individuals can only perform the operations that they are authorized for.
+- Management IP access restriction: Access control lists (ACLs) are deployed on the SGSN to limit the IP addresses or networks to ensure that only authorized personnel or devices are allowed access to network node elements, stored information, information flows, services and applications.
+- Password/secret stored locally in SGSN are in encrypted form and protected using strong algorithms (e.g., NIST approved algorithms).
+- Password lockout – SGSN detects repeated invalid attempts to sign into an account with incorrect passwords, i.e., by performing brute-force attack (for example, password guessing or dictionary based attacks, etc.).
+
+### IV.3 Availability dimension for module 1
+
+The availability security dimension ensures that there is no denial of authorized access to SGSN's stored information, information flows, services and applications due to network interruption. The following should be ensured:
+
+- Vulnerabilities of protocol are removed for management protocols of SGSN, i.e., file transfer protocol (FTP), Telnet, hypertext transport protocol (HTTP), and simple network management protocol (SNMP).
+
+- SGSN is able to handle all the malformed and anomalous traffic.
+- SGSN does not hang in a busy loop, causing a permanent denial-of-service situation.
+- SGSN software is provided with anti-source IP spoofing protection mechanisms like unicast Reverse path forwarding (RPF) and IP source guard (IPSG).
+
+### **IV.4 Non repudiation dimension for module 1**
+
+The non-repudiation dimension provides a record identifying each individual or device that accessed the SGSN and the record is to be used as a proof of access to the end-user data. The following should be ensured:
+
+- Audit data event generation: SGSN generates logs for the specified auditable event(s).
+- Audit data protection: Access and deletion of audit information is restricted to a certain subset of users.
+
+### **IV.5 Authentication dimension for module 1**
+
+Authentication is the provision of proof that the claimed identity of an entity is true. Entities include not only human users but also devices, services and applications. Entities are authenticated before performing any action on SGSN. The following should be ensured:
+
+- Management user authentication: Remote access to the SGSN for configuration and maintenance purposes is granted only to authenticated users.
+
+### **IV.6 Data integrity dimension for module**
+
+Data integrity is the property that data have not been altered in an unauthorized manner. Data integrity also ensures that information is protected against unauthorized modification. The following should be ensured:
+
+- Software integrity check feature for operating system (OS)/application image of SGSN is checked during the installation process.
+- SGSN supports the possibility of preventing illegal software installation by verifying its integrity (e.g., hashing for integrity check).
+
+### **IV.7 Privacy and data confidentiality dimension for module 1**
+
+Privacy considers the protection of the association of the identity of users and the activities performed by them. Data confidentiality considers the protection against unauthorized access to information asset. Encryption, access control lists, and file permissions are methods for data confidentiality. The following should be ensured:
+
+- Login credentials for the remote access are not captured by unauthorized user using application layer encryption protocols, such as hypertext transport protocol secure (HTTPS), SSHv2, or lower tunnelling protocol such as Internet protocol security (IPsec) virtual private network (VPN), transport layer security (TLS) VPN, etc.
+- The cryptographic algorithm used should not be affected by known attacks or vulnerabilities.
+
+### **IV.8 Communication security dimension for module 1**
+
+The communication security dimension ensures that information flows only between authorized end points. The following should be ensured:
+
+- IPSec tunnel employing AES128, AES192, and AES256 encryption algorithms between SGSN and GGSN is provided.
+- Secure data transmission is provided through the established IPSec tunnel between SGSN and GGSN.
+
+# Bibliography
+
+- [b-ITU-T X.800] Recommendation ITU-T X.800 (1991), *Security architecture for Open Systems Interconnection for CCITT applications*.
+- [b-ITU-T X.813] Recommendation ITU-T X.813 (1996), *Information technology – Open Systems Interconnection – Security frameworks for open systems: Non-repudiation framework*.
+- [b-ITU-T X.814] Recommendation ITU-T X.814 (1995), *Information technology – Open Systems Interconnection – Security frameworks for open systems: Confidentiality framework*.
+- [b-ITU-T X.1051] Recommendation ITU-T X.1051 (2016), *Information technology – Security techniques – Code of practice for Information security controls based on ISO/IEC 27002 for telecommunications organizations*.
+- [b-ITU-T X.1158] Recommendation ITU-T X.1158 (2014), *Multi-factor authentication mechanisms using a mobile device*.
+- [b-ITU-T X.1254] Recommendation ITU-T X.1254 (2012), *Entity authentication assurance framework*.
+- [b-ISO/IEC 27000] ISO/IEC 27000:2014, *Information technology – Security techniques – Information security management systems – Overview and vocabulary*.
+- [b-ISO/IEC 27033-1] ISO/IEC 27033-1:2015, *Information technology – Security techniques – Network security – Part 1: Overview and concepts*.
+- [b-ISO/IEC 27039] ISO/IEC 27039:2015, *Information technology – Security techniques – Selection, deployment and operations of intrusion detection and prevention systems (IDPS)*.
+- [b-ISO/IEC 29100] ISO/IEC 29100:2011, *Information technology – Security techniques – Privacy framework*.
+- [b-NIST SP 800-53] NIST Special Publication 800-53, *Security and Privacy Controls for Federal Information Systems and Organizations*.
+- [b-SECU] Secustar, *Criteria for information security readiness assessment*, Korea, October 2014.  
+([http://www.kfict.or.kr/board/index.html?board\\_id=business2&action=view&page=2&seq=13150](http://www.kfict.or.kr/board/index.html?board_id=business2&action=view&page=2&seq=13150))
+- [b-Wi-Fi] Wi-Fi Alliance  
+(<https://www.wi-fi.org/ko>)
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | General tariff principles                                                                                                                                 |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| Series F        | Non-telephone telecommunication services                                                                                                                  |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Terminals and subjective and objective assessment methods                                                                                                 |
+| Series Q        | Switching and signalling                                                                                                                                  |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| <b>Series X</b> | <b>Data networks, open system communications and security</b>                                                                                             |
+| Series Y        | Global information infrastructure, Internet protocol aspects and next-generation networks, Internet of Things and smart cities                            |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |

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+
+
+I n t e r n a t i o n a l   T e l e c o m m u n i c a t i o n   U n i o n
+
+# ITU-T
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+# X.1041
+
+(05/2018)
+
+SERIES X: DATA NETWORKS, OPEN SYSTEM  
+COMMUNICATIONS AND SECURITY
+
+Information and network security – Network security
+
+# --- **Security framework for voice-over-long-term- evolution (VoLTE) network operation**
+
+Recommendation ITU-T X.1041
+
+## ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY
+
+|                                                        |                      |
+|--------------------------------------------------------|----------------------|
+| PUBLIC DATA NETWORKS                                   | X.1–X.199            |
+| OPEN SYSTEMS INTERCONNECTION                           | X.200–X.299          |
+| INTERWORKING BETWEEN NETWORKS                          | X.300–X.399          |
+| MESSAGE HANDLING SYSTEMS                               | X.400–X.499          |
+| DIRECTORY                                              | X.500–X.599          |
+| OSI NETWORKING AND SYSTEM ASPECTS                      | X.600–X.699          |
+| OSI MANAGEMENT                                         | X.700–X.799          |
+| SECURITY                                               | X.800–X.849          |
+| OSI APPLICATIONS                                       | X.850–X.899          |
+| OPEN DISTRIBUTED PROCESSING                            | X.900–X.999          |
+| INFORMATION AND NETWORK SECURITY                       |                      |
+| General security aspects                               | X.1000–X.1029        |
+| <b>Network security</b>                                | <b>X.1030–X.1049</b> |
+| Security management                                    | X.1050–X.1069        |
+| Telebiometrics                                         | X.1080–X.1099        |
+| SECURE APPLICATIONS AND SERVICES (1)                   |                      |
+| Multicast security                                     | X.1100–X.1109        |
+| Home network security                                  | X.1110–X.1119        |
+| Mobile security                                        | X.1120–X.1139        |
+| Web security                                           | X.1140–X.1149        |
+| Security protocols (1)                                 | X.1150–X.1159        |
+| Peer-to-peer security                                  | X.1160–X.1169        |
+| Networked ID security                                  | X.1170–X.1179        |
+| IPTV security                                          | X.1180–X.1199        |
+| CYBERSPACE SECURITY                                    |                      |
+| Cybersecurity                                          | X.1200–X.1229        |
+| Countering spam                                        | X.1230–X.1249        |
+| Identity management                                    | X.1250–X.1279        |
+| SECURE APPLICATIONS AND SERVICES (2)                   |                      |
+| Emergency communications                               | X.1300–X.1309        |
+| Ubiquitous sensor network security                     | X.1310–X.1319        |
+| Smart grid security                                    | X.1330–X.1339        |
+| Certified mail                                         | X.1340–X.1349        |
+| Internet of things (IoT) security                      | X.1360–X.1369        |
+| Intelligent transportation system (ITS) security       | X.1370–X.1389        |
+| Distributed ledger technology security                 | X.1400–X.1429        |
+| Security protocols (2)                                 | X.1450–X.1459        |
+| CYBERSECURITY INFORMATION EXCHANGE                     |                      |
+| Overview of cybersecurity                              | X.1500–X.1519        |
+| Vulnerability/state exchange                           | X.1520–X.1539        |
+| Event/incident/heuristics exchange                     | X.1540–X.1549        |
+| Exchange of policies                                   | X.1550–X.1559        |
+| Heuristics and information request                     | X.1560–X.1569        |
+| Identification and discovery                           | X.1570–X.1579        |
+| Assured exchange                                       | X.1580–X.1589        |
+| CLOUD COMPUTING SECURITY                               |                      |
+| Overview of cloud computing security                   | X.1600–X.1601        |
+| Cloud computing security design                        | X.1602–X.1639        |
+| Cloud computing security best practices and guidelines | X.1640–X.1659        |
+| Cloud computing security implementation                | X.1660–X.1679        |
+| Other cloud computing security                         | X.1680–X.1699        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T X.1041
+
+# Security framework for voice-over-long-term-evolution (VoLTE) network operation
+
+## Summary
+
+Voice over LTE (VoLTE) is a voice communication service over IP multimedia subsystem (IMS) network, and its traffic is routed through long term evolution (LTE) wireless network, evolved packet core (EPC) core network and IMS core network. VoLTE adopts a full Internet protocol (IP) network framework based on session initiation protocol (SIP), which makes VoLTE more vulnerable to attacks than traditional voice service, which is based on circuit switch. Therefore, there is an urgent desire to establish the overall security framework for VoLTE network operation.
+
+Recommendation ITU-T X.1041 analyses security threats encountered by the VoLTE network and recommends countermeasures for telecommunication operators to ensure the secure operation. It also provides a security reference framework for VoLTE network.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T X.1041   | 2018-05-14 | 17          | <a href="http://handle.itu.int/11.1002/1000/13603">11.1002/1000/13603</a> |
+
+## Keywords
+
+Countermeasures, security reference framework, threats, VoLTE.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2018
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                           | Page |
+|-----------------------------------------------------------|------|
+| 1 Scope.....                                              | 1    |
+| 2 References.....                                         | 1    |
+| 3 Definitions .....                                       | 1    |
+| 3.1 Terms defined elsewhere .....                         | 1    |
+| 3.2 Terms defined in this Recommendation .....            | 1    |
+| 4 Abbreviations and acronyms .....                        | 1    |
+| 5 Conventions .....                                       | 3    |
+| 6 Introduction.....                                       | 3    |
+| 6.1 Background.....                                       | 3    |
+| 6.2 Threats analysis .....                                | 4    |
+| 6.3 Countermeasures .....                                 | 4    |
+| 6.4 Security reference architecture .....                 | 4    |
+| 7 Threats analysis .....                                  | 4    |
+| 7.1 Threats to data .....                                 | 4    |
+| 7.2 Threats to applications.....                          | 5    |
+| 7.3 Threats to network .....                              | 5    |
+| 7.4 Threats to infrastructure .....                       | 6    |
+| 8 Countermeasures.....                                    | 6    |
+| 8.1 Countermeasures for data security .....               | 6    |
+| 8.2 Countermeasures for application security .....        | 7    |
+| 8.3 Countermeasures for network security .....            | 8    |
+| 8.4 Countermeasures for infrastructure security .....     | 8    |
+| 8.5 Security management .....                             | 9    |
+| 9 Security reference architecture for VoLTE network ..... | 9    |
+| Bibliography.....                                         | 11   |
+
+
+
+# Recommendation ITU-T X.1041
+
+# Security framework for voice-over-long-term-evolution (VoLTE) network operation
+
+# 1 Scope
+
+This Recommendation analyses security threats encountered by VoLTE network and recommends countermeasures for telecommunication operators to ensure secure operation. It also provides a security reference framework for VoLTE network.
+
+This Recommendation:
+
+- Describes security threats to VoLTE network operation.
+- Provides technical and management measures for countering security threats.
+- Defines a security framework for VoLTE network operation.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+None.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+None.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following term:
+
+**3.2.1 session border controller (SBC):** A device deployed in VoLTE network to exert control over signalling and media streams involved in setting up, conducting, and tearing down telephone calls or other interactive media communications for the telecommunication operator. It provides functions such as security (e.g., Firewall, topology hiding), control-plane interworking between different protocols, network address translation, transcoding between different user-plane data types, load-balancing and routing, etc. [b-GSMA FCM.01].
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                  |
+|------|----------------------------------|
+| AKA  | Authentication and Key Agreement |
+| AS   | Application Server               |
+| CLR  | Cancel Location Request          |
+| CSCF | Call Session Control Function    |
+
+|         |                                                                           |
+|---------|---------------------------------------------------------------------------|
+| DB      | Database                                                                  |
+| DDoS    | Distributed Denial of Service                                             |
+| DoS     | Denial of Service                                                         |
+| ECGI    | Evolved Universal Terrestrial Radio Access Network Cell Global Identifier |
+| EPC     | Evolved Packet Core                                                       |
+| E-UTRAN | Evolved Universal Terrestrial Radio Access Network                        |
+| GUTI    | Globally Unique Temporary UE Identity                                     |
+| HSS     | Home Subscriber Server                                                    |
+| I-CSCF  | Interrogating Call Session Control Function                               |
+| IMEI    | International Mobile Equipment Identity                                   |
+| IMS     | IP Multimedia Subsystem                                                   |
+| IMSI    | International Mobile Subscriber Identity                                  |
+| IP      | Internet protocol                                                         |
+| IPSec   | IP Security Protocol                                                      |
+| ISDN    | Integrated Services Digital Network                                       |
+| LTE     | Long Term Evolution                                                       |
+| MME     | Mobile Management Entity                                                  |
+| MS      | Mobile Station                                                            |
+| MSISDN  | Mobile Subscriber International ISDN Number                               |
+| OM      | Operation and Management                                                  |
+| OS      | Operating System                                                          |
+| P-CSCF  | Proxy-Call Session Control Function                                       |
+| PDN     | Public Data Network                                                       |
+| PGW     | PDN Gateway                                                               |
+| QoS     | Quality of Service                                                        |
+| RSZI    | Regional Subscription Zone Identity                                       |
+| SBC     | Session Border Controller                                                 |
+| S-CSCF  | Serving-Call Session Control Function                                     |
+| SGW     | Serving Gateway                                                           |
+| SIP     | Session Initiation Protocol                                               |
+| SQL     | Structured Query Language                                                 |
+| TAI     | Tracking Area Identity                                                    |
+| TAS     | Telephony Application Server                                              |
+| TMSI    | Temporary Mobile Subscriber Identity                                      |
+| UE      | User Equipment                                                            |
+| VoLTE   | Voice over LTE                                                            |
+| XSS     | Cross-Site Scripting                                                      |
+
+# 5 Conventions
+
+In this Recommendation:
+
+The keywords "is required to" indicate a requirement which must be strictly followed and from which no deviation is permitted, if conformance to this Recommendation is to be claimed.
+
+The keywords "is recommended" indicate a requirement which is recommended but not absolutely required, if conformance to this Recommendation is to be claimed.
+
+# 6 Introduction
+
+## 6.1 Background
+
+VoLTE is a GSMA profile of the standards defined for the delivery of services (mainly voice) over the packet switched only network of long term evolution (LTE), leveraging the IP multimedia subsystem (IMS ) core network [b-GSMA FCM.01]. VoLTE is deemed as a standardized system for providing voice service for 4G mobile users.
+
+A VoLTE architecture is depicted in Figure 6-1. It is composed of a VoLTE mobile station (MS), evolved universal terrestrial radio access network (E-UTRAN), evolved packet core (EPC), IMS, home subscriber server (HSS) and various application servers (AS).
+
+![Figure 6-1 – VoLTE architecture diagram showing the components and their interconnections.](a234352dfaccdc24745c88eef7724cc6_img.jpg)
+
+The diagram illustrates the VoLTE architecture, organized into several layers and components. At the top, the 'AS' (Application Servers) layer includes 'TAS' (Telephony AS). Below this is the 'IMS' (IP Multimedia Subsystem) layer, which contains 'I/S-CSCF' (Inter/Session Control Function) and 'P-CSCF/SBC' (Proxy-Call Session Control Function/Session Border Controller). The 'EPC' (Evolved Packet Core) layer is the central core, containing 'S/P GW' (Serving/PDN Gateway) and 'MME' (Mobility Management Entity). The 'HSS' (Home Subscriber Server) is also part of the EPC layer. The 'E-UTRAN' (Evolved Universal Terrestrial Radio Access Network) layer is shown below the EPC, containing the 'eNodeB' (base station). At the bottom is the 'VoLTE MS' (VoLTE Mobile Station). Connections are shown as follows: TAS connects to I/S-CSCF. I/S-CSCF connects to P-CSCF/SBC. P-CSCF/SBC connects to HSS. HSS connects to MME. MME connects to S/P GW. S/P GW connects to eNodeB. eNodeB connects to VoLTE MS. There are also direct connections from I/S-CSCF and P-CSCF/SBC to the S/P GW.
+
+X.1041(18)\_F6-1
+
+Figure 6-1 – VoLTE architecture diagram showing the components and their interconnections.
+
+**Figure 6-1 – VoLTE architecture**
+
+VoLTE MS is the mobile terminal which is authorized to access the network and use VoLTE service. It may be a smartphone or tablet or another kind of communication device.
+
+E-UTRAN consists of eNodeBs which are in charge of wireless transceiver and base station control. The eNodeBs connect to the mobile management entity (MME) for signalling transmission, while data transmission is directly routed to the serving gateway (S-GW) and public data network (PDN) gateway (P-GW).
+
+EPC is the 4th generation of the 3GPP core network. The EPC basically contains MME and S/P-GW. MME is the most important control point in the core network and it is responsible for most of the control plane functions. S-GW is responsible for the quality of service (QoS). P-GW allocates IP addresses to user equipments (UEs), selects routes and provides interfaces towards Internet and IMS.
+
+IMS is a standalone system that connects to the LTE network via P-GW. VoLTE service is provided through the call session control function (CSCF) that controls the phone calls in the IMS network.
+
+The CSCF manages VoLTE registration information, connects calls and relays voice call transmission and reception. According to its dedicated function, the CSCF is classified into proxy CSCF (P-CSCF), interrogating CSCF (I-CSCF) and serving CSCF (S-CSCF). The main function of P-CSCF is to forward all SIP messages between the UE and the IMS. The I-CSCF finds the corresponding S-CSCF by querying HSS. The S-CSCF provides session management such as session set up, session deletion and session control.
+
+The main AS is called telephony application server (TAS) and it is responsible for both signalling and media manipulation for many services such as local number portability, free-call routing resolution, unified messaging and conference bridge services.
+
+The HSS contains all the information related to the subscribers and provides details of the subscribers to other network entities. The authentication center is part of HSS, which is responsible for generating authentication vectors for each subscriber.
+
+## **6.2 Threats analysis**
+
+VoLTE network is subject to various security threats and vulnerabilities. This Recommendation categorizes these threats into four groups:
+
+- 1) Threats to data: The threats to the sensitive data for VoLTE network operation.
+- 2) Threats to applications: The threats to session initiation protocol (SIP) signalling, voice media and other application services.
+- 3) Threats to networks, all the common threats to E-UTRAN, EPC and IMS network.
+- 4) Threats to infrastructure: The threats to the software and hardware of the VoLTE network elements.
+
+## **6.3 Countermeasures**
+
+This Recommendation describes security measures in five dimensions according to different types of threats in the VoLTE network.
+
+- 1) Countermeasures for data security.
+- 2) Countermeasures for application security.
+- 3) Countermeasures for network security.
+- 4) Countermeasures for infrastructure security.
+- 5) Security management.
+
+## **6.4 Security reference architecture**
+
+This Recommendation provides a security framework to address security challenges of the VoLTE network operation. The security framework is designed based on the analysis of threats and countermeasures.
+
+# **7 Threats analysis**
+
+VoLTE suffers from various security threats, such as the leakage of data, eavesdropping, flood attack and so on. These threats can be categorized into four groups: threats to data, threats to application, threats to network and threats to infrastructure.
+
+## **7.1 Threats to data**
+
+The network elements in VoLTE store important and sensitive data. It is essential to provide confidentiality, integrity and availability of these data.
+
+Sensitive data mainly includes the following:
+
+- Users' personal data: International mobile subscriber identity (IMSI), mobile station international subscriber directory number (MSISDN), international mobile equipment identity (IMEI), temporary mobile subscriber identity (TMSI), globally unique temporary user equipment identity (GUTI), etc.
+- Location data: Regional subscription zone identity (RSZI), tracking area identity (TAI), evolved universal terrestrial radio access network cell global identifier (ECGI), latitude and longitude of eNodeBs, etc.
+- Network authentication data: Root key, authentication parameters, encryption key, integrity key, etc.
+- Users' service data: Access time, online time, call time, credit rating, arrears, billing, etc.
+
+Sensitive data are subject to information disclosure in the process of data storage, as well as data transmission, data usage, and data destruction. The disorganized management of staff, computer rooms and equipment, can result in serious security risks. Moreover, some malicious attacks can also lead to sensitive data leakage. For example, an attacker may eavesdrop on data transmitted over the air interface and use a stolen key to decrypt user data or signalling. Attackers can also utilize the diameter protocol to launch inter-network location queries, and illegally obtain user location.
+
+## **7.2 Threats to applications**
+
+The application layer of the VoLTE system refers to the services above IP layer, including the SIP signalling, the voice media, and the supplementary web services.
+
+### **7.2.1 Threats to SIP signalling**
+
+VoLTE uses the SIP protocol to carry the signalling messages. Attackers can exploit the vulnerabilities of SIP to launch SIP malformed packet attack, and DoS attack.
+
+SIP malformed packets do not conform to SIP protocol specifications such as [b-IETF RFC 3261] and [b-IETF RFC 3455]. It is easy to maliciously customize SIP malformed packets to detect the vulnerabilities of SIP protocol stack. The imperfections of an abnormal SIP signalling processing mechanism can lead to system exceptions, or even server crash.
+
+The attackers may attempt to inject a large amount of SIP messages to abuse the crucial resources of the core network, such as bandwidth, session and processing capability, and to degrade the network performance or to make the network unable to provide services.
+
+### **7.2.2 Threats to VoLTE voice media**
+
+Threats to VoLTE voice media include caller ID spoofing, session hijack, etc. Attackers may also construct non-compliant media packets to launch DoS attack on session border controller (SBC) or remote media servers.
+
+### **7.2.3 Threats to web services**
+
+As indicated in Figure 6-1, there is a main AS called TAS responsible for many services in VoLTE. Besides voice services, TAS also contains a web server to provide supplementary services, such as call forwarding, which can be configured and managed by subscribers via the Internet. The web server may suffer from common web threats such as structured query language (SQL) injection or cross-site scripting (XSS).
+
+## **7.3 Threats to network**
+
+In the VoLTE system, threats to the network come from two sources: attacks from the Internet, and attacks from other networks.
+
+The VoLTE network connects with the Internet through the SGi interface, and this interface is the source of remote attacks on the core network from the Internet.
+
+The interchanging of protocol between different networks, such as Diameter, may cause a substantial security risk if not protected properly. For example, attackers can forge a Diameter cancel location request (CLR) signalling message to intercept any user's VoLTE service, or send other kinds of Diameter messages to initiate attacks on MME, HSS or other VoLTE network elements.
+
+## **7.4 Threats to infrastructure**
+
+Threats to infrastructure include but are not limited to:
+
+- Operating system (OS)/database (DB) vulnerability exploitation: OS and DB vulnerabilities are usually due to improper programming or other functional self-defects introduced during the system design or development process. OS and DB vendors continuously publish patches for known vulnerabilities. If VoLTE equipment's do not apply these patches in a timely manner, attackers may exploit these vulnerabilities and cause damages.
+- Improper security configuration: Improper security configuration can lead to the misuse of files and directories. If there is no mechanism to ensure that the passwords are strong enough, updated periodically and stored in encrypted storage, attackers can log onto the device illegally and control it maliciously by the means of brute force attacks. If P-GW is not properly configured, illegal direct IP connections may be established between the VoLTE MSs and cause DoS billing issues for VoLTE users.
+- Unauthorized physical access: If unauthorized devices physically access the VoLTE network, attackers can use them to steal sensitive data, or even destroy the continuity of VoLTE network operation.
+- Malicious software: Malicious software, such as zombies, trojans and worms, which are installed illegally, may cause severe consequences, such as, rendering the system unstable, turning the equipment into maliciously controlled devices, data theft, or interruption of VoLTE network services.
+
+# **8 Countermeasures**
+
+To protect the security of VoLTE network, schemes combining technology and management measures are needed. This Recommendation describes the countermeasures in five dimensions: data security, application security, network security, infrastructure security and security management.
+
+## **8.1 Countermeasures for data security**
+
+### **8.1.1 The security of data storage**
+
+When data are stored in the VoLTE network, certain measures should be taken to ensure the security of data storage such as the following:
+
+- Data should be managed in accordance with data sensitivity and stored based on its security levels.
+- The storage of sensitive data should be securely protected. Related measures include, but are not limited to, the following: establishing the authentication and access control mechanism, and conducting regular risk assessments.
+- Data backup and recovery mechanism should be enforced. Data disaster emergency plans must be prepared in advance. Once data are lost or destroyed, they must be detected and recovered in a timely manner.
+
+### **8.1.2 The security of data transmission**
+
+When data packets are transported across various networks or systems, certain measures should be taken to prevent data disclosure during transmission.
+
+- Prior to transmitting sensitive data to other systems, it is required that the system be reliable.
+
+- Transmitted data should be encrypted using secure encryption algorithms.
+
+### **8.1.3 The security of data destruction**
+
+When a service system containing sensitive data is removed from service, or when sensitive data are expected to expire, reliable technical measures are required to ensure that sensitive data are destroyed and cannot be restored. Regarding data destruction, the following should be ensured:
+
+- The data destruction process should be established, and action taken when users withdraw from the service, or data are beyond the retention period.
+- The data destruction process should be recorded for follow-up security audits.
+- Once sensitive data has been destroyed, reliable technical measures should be used to ensure that the data cannot be restored.
+
+## **8.2 Countermeasures for application security**
+
+### **8.2.1 SIP signalling reinforcement**
+
+The main countermeasures for malformed SIP packets include protocol conformance checking and protocol robustness verification using the multi-level filtering mechanism. It is recommended that the following malformed SIP packets should be filtered:
+
+- Overlength segment packets: When the length of the SIP packet exceeds a specified threshold.
+- Multi-header-fields SIP packet: When the number of fields, such as via, contact or route, in a SIP packet exceeds the specified threshold.
+- SIP packets with incorrect IP address: When the IP address in the via header is different from the source IP of the transport layer.
+- Self-loop SIP packets: When the IP addresses of sender and receiver are identical.
+
+### **8.2.2 SIP signalling flood prevention**
+
+Some restriction schemes, as listed below, should be applied according to the features of the SIP signalling to prevent DoS attacks.
+
+- Limiting the rate of requests per single user in an SBC: Limit the number of register requests during a period by single user for the SBC to eliminate register signalling attacks.
+- Limit total SIP signalling rates for all users in core network to prevent DoS attacks.
+- SIP signalling should be analyzed by classification and statistics to determine whether the behavior is aggressive. If the user is identified as having an aggressive behavior, the packet rate should be limited or the packets should be dropped.
+
+### **8.2.3 Voice media security**
+
+IMS-AKA should be deployed and enforced to authenticate the MS and IMS network to prevent caller ID spoofing attack and session hijack attack. The network should have the capability to filter illegal media packets.
+
+The SBC should be examined for the legitimacy of received media packets. This can prevent attackers from initiating media packet attacks that can affect the normal operations of legitimate users.
+
+### **8.2.4 Web service security**
+
+Measures should be taken to ensure the security of the websites, such as format legitimacy, checking of user input and regular security inspection on the website.
+
+## **8.3 Countermeasures for network security**
+
+### **8.3.1 Security deployment**
+
+Security deployment is achieved by isolating the various security domains. Systems with the same security attributes and similar security levels should be deployed into the same security domain. Appropriate security policies should be configured to control inter-domain access between different security domains. It is necessary to divide VoLTE network into security domains, such as: wireless access security domain, core network security domain, operation and management (O&M) network security domain, billing security domain, etc.
+
+### **8.3.2 Inter-networking security**
+
+It is necessary to ensure the security of the connection between the VoLTE network and a 2G/3G core network, as well as the connection between different VoLTE network operators. Hence the security protection measures of boundaries between different networks should be taken to ensure interconnection security. Networks must be segregated and boundary protection equipment such as SBC or firewalls should be deployed.
+
+### **8.3.3 Multiple protection mechanism**
+
+Deploy dedicated security protective devices in a VoLTE network to realize network security-in-depth defences, such as firewalls, anti distributed denial of service (DDoS) systems and IPS equipment, ensure that abnormal traffic or malicious behaviour can be detected and blocked in a timely manner.
+
+### **8.3.4 IP transmission encryption**
+
+It is required to deploy IP security protocol (IPSec) to ensure the confidentiality of IP transmission. An IPSec tunnel should be established between the MS and P-CSCF to protect confidentiality of SIP signalling [b-3GPP TS 24.229].
+
+## **8.4 Countermeasures for infrastructure security**
+
+### **8.4.1 Security baseline for net equipment configuration**
+
+It is necessary to set up a standardized security baseline for the configuration of a VoLTE infrastructure.
+
+The security baseline includes the authentication and authorization requirement, security logging and audit.
+
+The VoLTE infrastructure should be configured according to the security baseline.
+
+The network elements that need to be securely configured include: OS, DB, router, firewall, server, LTE/EPC, IMS, etc.
+
+Some common baseline requirements for the network elements are:
+
+- Unnecessary and unsafe network ports or services should be closed.
+- Access to the file systems should be granted with least-privilege.
+- Strong password should be enforced for each account, and unnecessary accounts should be deleted.
+
+In particular, P-GW should be configured to prohibit the direct IP communication between different MSs. It is recommended that P-GW should be configured to only allow communication between MS and the CSCF for SIP signalling and communication between the MS and the internal DNS server.
+
+### **8.4.2 Physical access security**
+
+The hosting environment of the communication infrastructure should be regulated to prevent unauthorized access.
+
+### **8.4.3 Software integrity protection**
+
+Software integrity protection should be designed to prevent system and application software from being illegally tampered with. Software component integrity should be verified by using an integrity protection algorithm.
+
+## **8.5 Security management**
+
+The security management for VoLTE network addresses the risks before, during and after the event.
+
+### **8.5.1 Security evaluation**
+
+It is required to establish an internal security evaluation process and recommended to pass the third-party authorities' security certification, such as EAL3 of CC [b-ISO/IEC CC].
+
+### **8.5.2 Security operation and maintenance**
+
+Some measures should be taken to ensure the security of daily operation and maintenance, such as periodical network/service vulnerability scanning, regular software robustness testing, centralized log management, etc.
+
+### **8.5.3 Security risk response and disposal**
+
+It is required to take worldwide security events into account. Threat intelligence and globally exposed vulnerabilities should be collected in a timely manner and risk analysis should be updated accordingly. A security operation workflow to guide the risk analysis and system reinforcement should be set up with high efficiency. Once the threat intelligence that may affect the operation of VoLTE network is disclosed, the workflow should be activated in time to make sure that the threats and risks are properly disposed.
+
+# **9 Security reference architecture for VoLTE network**
+
+Based on the above analysis of threats and countermeasures, the recommended security reference framework for VoLTE network is shown in Figure 9-1:
+
+![Figure 9-1 – Security reference framework for VoLTE network operation. The diagram shows a three-column framework: Security management, Countermeasures, and Threats. Security management includes evaluation, operation, and risk response. Countermeasures are categorized by Data, Application, Network, and Infrastructure security. Threats are categorized by Data, Application, Network, and Infrastructure threats. Arrows point from threats to countermeasures.](fa859e4e468bfb2710a94527f2c504af_img.jpg)
+
+| Security management                                                                                      | Countermeasures                                                                                                                                | Threats                                                                                                                |
+|----------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------|
+| Security evaluation<br><br>Security operation and maintenance<br><br>Security risk response and disposal | <b>Data security</b><br>The security of data storage<br>The security of data transmission<br>The security of data destruction                  | <b>Threats to data:</b> sensitive data leakage, data corruption and data tampering, etc.                               |
+|                                                                                                          | <b>Application security</b><br>SIP signalling reinforcement<br>SIP signalling flood prevention<br>Voice media security<br>Web service security | <b>Threats to application:</b> SIP signalling attack, caller ID spoofing, billing evasion, SQL injection and XSS, etc. |
+|                                                                                                          | <b>Network security</b><br>Security deployment<br>Inter-networking security<br>Multiple protection mechanism<br>IP transmission encryption     | <b>Threats to network:</b> remote attacks from Internet, Dos, etc.                                                     |
+|                                                                                                          | <b>Infrastructure security</b><br>Security baseline for configuration<br>Physical access security<br>Software integrity protection             | <b>Threats to infrastructure:</b> OS/DB vulnerability exploitation, unauthorized accessing, directories misuse, etc.   |
+
+X.1041(18)\_F9-1
+
+Figure 9-1 – Security reference framework for VoLTE network operation. The diagram shows a three-column framework: Security management, Countermeasures, and Threats. Security management includes evaluation, operation, and risk response. Countermeasures are categorized by Data, Application, Network, and Infrastructure security. Threats are categorized by Data, Application, Network, and Infrastructure threats. Arrows point from threats to countermeasures.
+
+**Figure 9-1 – Security reference framework for VoLTE network operation**
+
+The framework is designed to address the security challenges of VoLTE network operation. It classifies the security threats into four groups (Data, Application, Network, and Infrastructure), provides technical countermeasures for each group, and contains management countermeasures for all the four groups.
+
+This Recommendation lists the most common and representative security threats and corresponding countermeasures for VoLTE network operation, and organize them into the above security reference framework. It should be understood that due to the complexity of the VoLTE network deployment, all the security threats and countermeasures cannot be exhausted in a single document. At the same time, the threats in VoLTE network evolve continually and countermeasures need to be reinforced constantly.
+
+The security reference framework in this Recommendation is designed to help operators and vendors better understand threats and to efficiently counter the attacks encountered or those that are imminent in the years to come. It is recommended that VoLTE network operators and vendors use this security reference framework to identify and organize any future threats and/or countermeasures, and improve their capabilities to cope with the security challenges of VoLTE network operation.
+
+# Bibliography
+
+- [b-IETF RFC 3261] IETF RFC 3261 (2002), *SIP: Session Initiation Protocol*.
+- [b-IETF RFC 3455] IETF RFC 3455 (2003), *Private Header (P-Header) Extensions to the Session Initiation Protocol (SIP) for the 3rd-Generation Partnership Project (3GPP)*.
+- [b-3GPP TS 23.228] 3GPP TS 23.228:2014, *IP Multimedia Subsystem (IMS)*.
+- [b-3GPP TS 24.229] 3GPP TS 24.229:2017, *IP multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP)*.
+- [b-ISO/IEC CC] ISO/IEC 15408-1:2009, *Information technology – Security techniques – Evaluation criteria for IT Security – Part 1: Introduction and general model*.
+- [b-GSMA FCM.01] GSMA FCM.01:2014, *VoLTE Service Description and Implementation Guidelines Version 2.0*.
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                           |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                         |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                       |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                         |
+| Series F        | Non-telephone telecommunication services                                                                                                                  |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                              |
+| Series H        | Audiovisual and multimedia systems                                                                                                                        |
+| Series I        | Integrated services digital network                                                                                                                       |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                               |
+| Series K        | Protection against interference                                                                                                                           |
+| Series L        | Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                       |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                           |
+| Series O        | Specifications of measuring equipment                                                                                                                     |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                              |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                           |
+| Series R        | Telegraph transmission                                                                                                                                    |
+| Series S        | Telegraph services terminal equipment                                                                                                                     |
+| Series T        | Terminals for telematic services                                                                                                                          |
+| Series U        | Telegraph switching                                                                                                                                       |
+| Series V        | Data communication over the telephone network                                                                                                             |
+| <b>Series X</b> | <b>Data networks, open system communications and security</b>                                                                                             |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                               |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                      |