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By using historic bitcoin to USD exchange rates, we estimate a total of 25 million USD was extorted with these NetWalker related transactions. | [] | Take a NetWalk on the Wild Side |
Even though we do not have complete visibility into the BTC flow before NetWalker started ramping up, one thing is certain, this quarter alone it has been highly successful at extorting organisations for large amounts of money. | [] | Take a NetWalk on the Wild Side |
All this at a time when many sectors are struggling because people are sheltering in place and governments are trying to keep businesses from going bankrupt. | [] | Take a NetWalk on the Wild Side |
NetWalker is making millions off the backs of legitimate companies. | [] | Take a NetWalk on the Wild Side |
Figure 25. | [] | Take a NetWalk on the Wild Side |
Overview of uncovered bitcoin transactions, highlighting the two identified actor addresses. | [] | Take a NetWalk on the Wild Side |
Observed Changes While talking about the impact of NetWalker with our partners, we learned that the change in modus operandi not only affected the way the actors communicate with their victims. | [] | Take a NetWalk on the Wild Side |
When there was a change from email communication to a dedicated Tor hidden service, the actors also moved away from using legacy bitcoin addresses to SegWit addresses. | [] | Take a NetWalk on the Wild Side |
The benefits of using the newer SegWit addresses include faster transaction time and lower transaction cost. | [] | Take a NetWalk on the Wild Side |
The NetWalker advertisement on the underground forum mentions instant and fully automatic payments around the time of this observed change. | [] | Take a NetWalk on the Wild Side |
This makes us believe the ransomware actors were professionalizing their operation just before expanding to the Ransomware-as-a-Service model. | [] | Take a NetWalk on the Wild Side |
Comparison with Previous Ransomware Given the sudden appearance of NetWalker ransomware and the associated threat actor, it suggests that some prior knowledge on ransomware development or underground presence had to be in place. | [] | Take a NetWalk on the Wild Side |
Armed with this hypothesis, we searched for possible links to underground actors and other ransomware strains that might fit the bill. | [] | Take a NetWalk on the Wild Side |
We came across one threat actor offering ransomware that caught our attention. | [] | Take a NetWalk on the Wild Side |
It was the use of the name NetWalker, in combination with a strong ransomware connection, that sparked our interest. | [] | Take a NetWalk on the Wild Side |
Some years ago, a threat actor using the moniker Eriknetwalker was advertising ransomware on several underground forums. | [] | Take a NetWalk on the Wild Side |
We found posts from 2016 and the latest public activity was around June 2019, several months before NetWalker ransomware made its appearance. | [] | Take a NetWalk on the Wild Side |
Figure 26. | [] | Take a NetWalk on the Wild Side |
Eriknetwalker began advertising their ransomware in 2016 (Google-translated from Russian) | [] | Take a NetWalk on the Wild Side |
Based on our underground research, we linked the moniker Eriknetwalker to the development and/or distribution of Amnesia, Bomber and Scarab ransomware. | [] | Take a NetWalk on the Wild Side |
Eriknetwalker stopped advertising ransomware around June 2019. | [] | Take a NetWalk on the Wild Side |
Therefore, we decided to perform a comparative analysis between the different ransomware strains linked to Eriknetwalker and some of the earliest versions of NetWalker we could find. | [] | Take a NetWalk on the Wild Side |
The goal of this comparative analysis was to identify whether there was an overlap between source codes. | [] | Take a NetWalk on the Wild Side |
Such overlap could suggest a stronger link between the current NetWalker version and the other ransomware versions from Eriknetwalker, possibly even explaining the name overlap. | [] | Take a NetWalk on the Wild Side |
To execute the analysis, we used several tools one of which was the binary visualization tool Veles, which dynamically translates binary information into an abstract visualization that allows us to identify and compare patterns. | [] | Take a NetWalk on the Wild Side |
The different types of ransomware we began analyzing were the variants of Amnesia, Scarab, and NetWalker. | [] | Take a NetWalk on the Wild Side |
Figure 27. | [] | Take a NetWalk on the Wild Side |
Flat visualization of binary data of the different ransomware variants Figure 28. | [] | Take a NetWalk on the Wild Side |
3D visualization of binary data of the different ransomware variants Visualizing data in such a manner is a way to use the human brain to quickly identify patterns and be able to draw comparisons between objects. | [] | Take a NetWalk on the Wild Side |
In our case, we see that, based on the binary data visualized in Figures 27 and 28, the ransomware binaries do yield differences that we cannot ignore. | [] | Take a NetWalk on the Wild Side |
Figure 29. | [] | Take a NetWalk on the Wild Side |
Comparison of source code results Figure 29 shows the results of a source code similarity analysis led on the different variants of ransomware named in the figure itself. | [] | Take a NetWalk on the Wild Side |
Interesting enough, Scarab and Amnesia show a higher overlap with Buran and Zeppelin than the early NetWalker samples. | [] | Take a NetWalk on the Wild Side |
The percentages shown are the amount of code that is similar between two variants. | [] | Take a NetWalk on the Wild Side |
As illustrated in the overview, the September 2019 NetWalker version has a different codebase from the ErikNetWalker-linked ransomware variants. | [] | Take a NetWalk on the Wild Side |
This finding disproves our earlier hypothesis that NetWalker is linked to the older Amnesia variants based on code overlap. | [] | Take a NetWalk on the Wild Side |
Often, research teams do not publish their results when it disproves their own hypothesis. | [] | Take a NetWalk on the Wild Side |
However, for the sake of transparency, we decided to include our research efforts. | [] | Take a NetWalk on the Wild Side |
YARA Rules We uploaded a YARA rule to detect almost all the samples observed in the wild to date. | [] | Take a NetWalk on the Wild Side |
Indicators of Compromise During our investigation we have observed numerous IoCs linked to NetWalker ransomware. | [] | Take a NetWalk on the Wild Side |
To obtain them please visit our McAfee ATR GitHub site, or get the latest NetWalker IoCs and intelligence on many other threats with McAfee Insights. | [] | Take a NetWalk on the Wild Side |
MITRE ATT&CK Techniques | [] | Take a NetWalk on the Wild Side |
The below techniques were based on our research and complemented with research from industry peers. | [] | Take a NetWalk on the Wild Side |
Initial Access Exploit Public-Facing Application (T1190) : Exploit Tomcat, Exploit WebLogic Spear phishing Attachment (T1566.001): | [] | Take a NetWalk on the Wild Side |
Phishing email Valid Accounts (T1078): RDP compromised Execution PowerShell (T1059.001): | [] | Take a NetWalk on the Wild Side |
PowerShell Script Command and Scripting Interpreter: | [] | Take a NetWalk on the Wild Side |
Windows Command Shell (003) Service Execution (T1569.002): | [] | Take a NetWalk on the Wild Side |
PsExec Native API (T1106): Use Windows API functions to inject DLL Windows Management Instrumentation (T1047) Persistence Registry Run Key (T1547.001): | [
"T1055",
"T1106"
] | Take a NetWalk on the Wild Side |
Place a value on RunOnce key Modify Registry key (T1112): Create its own registry key in \SOFTWARE\<uniquename> Privilege Escalation Exploitation for Privilege Escalation (T1068): CVE-2020-0796, CVE-2019-1458, CVE-2017-0213, CVE-2015-1701 Process Injection (T1055.001): Reflective DLL Injection Defense Evasion Disabling... | [
"T1027",
"T1112",
"T1547.001"
] | Take a NetWalk on the Wild Side |
System Information Discovery (T1082) Lateral Movement Third-Party Software (T1072): TeamViewer, Anydesk Service Execution (T 1569.002): PsExec Lateral Tool Transfer (T1570) Collection Data from information repositories (T1213) Data from local system (T1005) Data from network shared drive (T1039) Command and Control Ing... | [] | Take a NetWalk on the Wild Side |
Impact Data Encrypted (T1486): NetWalker Ransomware Inhibit System Recovery (T1490): Shadow Copies Deleted Service Stop (T1489) Conclusion Ransomware has evolved into a lucrative business for threat actors, from underground forums selling ransomware, to offering services such as support portals to guide victims through... | [] | Take a NetWalk on the Wild Side |
McAfee’s Advanced Threat Research team has analysed the NetWalker ransomware and have been following its evolution from the initial sighting of the Mailto ransomware to its redevelopment into the NetWalker ransomware. | [] | Take a NetWalk on the Wild Side |
The recent shift to a business-centric model of Ransomware-as-a-Service is a clear sign that it is stepping up, so it seems that the NetWalker group is following in the footsteps of REvil and other successful RaaS groups. | [] | Take a NetWalk on the Wild Side |
The ransomware developers have proven the ability to refocus and capitalize on current world events and develop lures to help ensure the effectiveness of the ransomware, which has allowed them to become selective of their affiliates by limiting access to the ransomware to only those with vetted access to large organiza... | [] | Take a NetWalk on the Wild Side |
As development of the ransomware continues, we have witnessed recent shifts in activity that closely follow in the footsteps of other ransomware developments, including threatening victims with the release of confidential information if the ransom is not met. | [] | Take a NetWalk on the Wild Side |
McAfee ATR is actively monitoring ransomware threats and will continue to update McAfee MVISION Insights and its social networking channels with new and current information. | [] | Take a NetWalk on the Wild Side |
MVISION Insights is the only proactive endpoint security solution that simultaneously prioritizes and predicts threats that matter to our customers while offering prescriptive guidance on what to do in their local environment. | [] | Take a NetWalk on the Wild Side |
Want to stay ahead of the adversaries? | [] | Take a NetWalk on the Wild Side |
Check out McAfee MVISION Insights for more information. | [] | Take a NetWalk on the Wild Side |
If you want to experience some of the MVISION Insights capabilities, go the Preview of MVISION Insights where you can select the top threat information that is available. | [] | Take a NetWalk on the Wild Side |
Authored by: Thibault Seret, Valentine Mairet, Jeffrey Sman, Alfred Alvarado, Tim Hux, Alexandre Mundo, John Fokker, Marc Rivero Lopez and Thomas Roccia. | [] | Take a NetWalk on the Wild Side |
The post Take a “NetWalk” on the Wild Side appeared first on McAfee Blog. | [] | Take a NetWalk on the Wild Side |
Microsoft researchers recently investigated an attack where malicious OAuth applications were deployed on compromised cloud tenants and then used to control Exchange servers and spread spam. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The investigation revealed that the threat actor launched credential stuffing attacks against high-risk accounts that didn’t have multi-factor authentication (MFA) enabled and leveraged the unsecured administrator accounts to gain initial access. | [
"T1110"
] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The unauthorized access to the cloud tenant enabled the actor to create a malicious OAuth application that added a malicious inbound connector in the email server. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The actor then used the malicious inbound connector to send spam emails that looked like they originated from the targets’ domain. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The spam emails were sent as part of a deceptive sweepstakes scheme meant to trick recipients into signing up for recurring paid subscriptions. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
Microsoft has been monitoring the rising popularity of OAuth application abuse. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
One of the first observed malicious usage of OAuth applications in the wild is consent phishing. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
Consent phishing attacks aim to trick users into granting permissions to malicious OAuth apps to gain access to user’s legitimate cloud services (mail servers, files storage, management APIs, etc.). | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
In the past few years, Microsoft has observed that more and more threat actors, including nation-state actors, have been using OAuth applications for different malicious purposes – command-and-control (C2) communication, backdoors, phishing, redirections, and so on. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
This recent attack involved a network of single-tenant applications installed in compromised organizations being used as the actor’s identity platform to perform the attack. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
As soon as the network was revealed, all the related applications were taken down and notifications to customers were sent, including recommended remediation steps. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
This blog presents the technical analysis of this attack vector and the succeeding spam campaign attempted by the threat actor. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
It also provides guidance for defenders on protecting organizations from this threat, and how Microsoft security technologies detect it. Figure 1. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
Overview of the attack chain. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The time between application deployment and usage varied; there were cases where the actor took months before using the application. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
Initial access For the attack to succeed, the threat actor needed to compromise cloud tenant users with sufficient permissions that would allow the actor to create an application in the cloud environment and give it admin consent. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The actor performed credential stuffing attacks against their targets, attempting to access users with the global admin role. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The authentication attempts, which originated from a single IP address, were launched against the Azure Active Directory PowerShell application (app ID: 1b730954-1685-4b74-9bfd-dac224a7b894). | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The same application was later used to deploy the rest of the attack. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
Based on the success ratio of the authentication attempts, it is inferred that the attacker used a dump of compromised credentials. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The investigation also revealed that 86% of the compromised tenants had at least one admin with a real-time high risk score, which means they were flagged by Azure AD Identity Protection to be most likely compromised. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
It is also important to note that all the compromised admins didn’t have MFA enabled, which could have stopped the attack. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
These observations amplify the importance of securing accounts and monitoring for high-risk users, especially those with high privileges. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
Deploying malicious OAuth application Once the threat actor gained access to privileged users, their next step was to set up the malicious application. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
Based on analysis of the event user agent (Swagger-Codegen/1.4.0.0/csharp) and how quickly the deployment of the application was done, it is likely that the actor ran a PowerShell script to perform the following Azure Active Directory (AAD) management activities in all targeted tenants: Register a new single–tenant app... | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The activities mentioned gave the threat actor control of a highly privileged application. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
It was observed that the threat actor did not always use the application right after it was deployed. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
In some cases, it took weeks or months before the application was utilized. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
Also, in organizations that didn’t monitor for suspicious applications, the applications were deployed for months and used multiple times by the threat actor. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
Modifying Exchange settings The threat actor used the privileged application to authenticate the Exchange Online PowerShell module and modify the Exchange settings of the compromised server. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
There were two modifications which allowed them to perform the next step in the attack chain: Create a new inbound connector Connectors are a collection of instructions that customize the way email flows to and from organizations using Microsoft 365 or Office 365. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
Most organizations using Microsoft 365 and Office 365 don’t need custom connectors for regular mail flow, but some use it when they need to process messages from another messaging system that’s not running Exchange, or if they have a network appliance that performs policy checks and then routes messages to their Exchan... | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The threat actor set a new inbound connector with the naming convention Ran_([a-zA-Z]){5} (for example Ran_xAFzd). | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The purpose of the inbound connector was to allow mails from certain IPs (that are related to the attacker’s infrastructure) to flow through the victim’s Exchange server. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
This allowed the threat actor to send emails that looked like they originated from the compromised Exchange domain. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The configuration information for the newly created connectors were seen in Exchange audit event New-InboundConnector. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The following table shows the configuration parameters in the audit event related to this change: NameValue“Name”“Ran_jBelh”“Enabled”“True”“CloudServicesMailEnabled”“True”“RestrictDomainsToCertificate”“False”“SenderDomains”“smtp:*;1”“SenderIPAddresses”“170.75.174.97;170.75.172.8;170.75.170.69;170.75.174.95; 54.39.94.14... | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
The threat actor utilized this feature to set 12 new transport rules with the naming convention of Test01 to Test012. | [] | Malicious OAuth applications used to compromise email servers and spread spam Microsoft Security Blog |
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