Datasets:
Devilishcode
/
hacking

Dataset card Data Studio Files
xet
 Community
text
stringlengths
0
1.99k
Resolution of the /etc/passwd file's readability does not entirely solve the
basic problem with passwords. Educating users and administrators is necessary
to assure proper password utilization. First, "good passwords are those that
are at least six characters long, aren't based on personal information, and
have some non-alphabetic (especially control) characters in them: 4score,
my_name, luv2run" (8). Secondly, passwords should be changed periodically but
users should avoid alternating between two passwords. Different passwords for
different machines and files will aid in protecting sensitive information.
Finally, passwords should never be available to unauthorized users. Reduction
of user ignorance about poor password choice will inevitably make a system
more secure.
NETWORK SECURITY
UUCP system
The most common Unix system network is the UUCP system, which is a group of
programs that perform the file transfers and command execution between remote
systems. (3) The problem with the UUCP system is that users on the network
may access other users' files without access permission. As stated by Nowitz
(9),
The uucp system, left unrestricted, will let any outside user execute
commands and copy in/out any file that is readable/writable by a uucp login
user. It is up to the individual sites to be aware of this, and apply the
protections that they feel free are necessary.
This emphasizes the importance of proper implementation by the system
administrator.
There are four UUCP system commands to consider when looking into network
security with the Unix system. The first is uucp, a command used to copy
files between two Unix systems. If uucp is not properly implemented by the
system administrator, any outside user can execute remote commands and copy
files from another login user. If the file name on another system is known,
one could use the uucp command to copy files from that system to their system.
For example:
%uucp system2!/main/src/hisfile myfile
will copy hisfile from system2 in the directory /main/src to the file myfile
in the current local directory. If file transfer restrictions exist on either
system, hisfile would not be sent. If there are no restrictions, any file
could be copied from a remote user - including the password file. The
following would copy the remote system /etc/passwd file to the local file
thanks:
%uucp system2!/etc/passwd thanks
System administrators can address the uucp matter by restricting uucp file
transfers to the directory /user/spool/uucppublic. (8) If one tries to
transfer a file anywhere else, a message will be returned saying "remote
access to path/file denied" and no file transfer will occur.
The second UUCP system command to consider is the uux. Its function is to
execute commands on remote Unix computers. This is called remote command
execution and is most often used to send mail between systems (mail executes
the uux command internally).
The ability to execute a command on another system introduces a serious
security problem if remote command execution is not limited. As an example, a
system should not allow users from another system to perform the following:
%uux "system1!cat</etc/passwd>/usr/spool/uucppublic"
which would cause system1 to send its /etc/passwd file to the system2 uucp
public directory. The user of system2 would now have access to the password
file. Therefore, only a few commands should be allowed to execute remotely.
Often the only command allowed to run uux is rmail, the restricted mail
program.
The third UUCP system function is the uucico (copy in / copy out) program.
It performs the true communication work. Uucp or uux does not actually call
up other systems; instead they are queued and the uucico program initiates the
remote processes. The uucico program uses the file /usr/uucp/USERFILE to
determine what files a remote system may send or receive. Checks for legal
files are the basis for security in USERFILE. Thus the system administrator
should carefully control this file.
In addition, USERFILE controls security between two Unix systems by allowing
a call-back flag to be set. Therefore, some degree of security can be
achieved by requiring a system to check if the remote system is legal before a
call-back occurs.
The last UUCP function is the uuxqt. It controls the remote command
execution. The uuxqt program uses the file /usr/lib/uucp/L.cmd to determine
which commands will run in response to a remote execution request. For
example, if one wishes to use the electronic mail feature, then the L.cmd file
will contain the line rmail. Since uuxqt determines what commands will be
allowed to execute remotely, commands which may compromise system security
should not be included in L.cmd.
CALL THE UNIX SYSTEM
In addition to UUCP network commands, one should also be cautious of the cu
command (call the Unix system). Cu permits a remote user to call another
computer system. The problem with cu is that a user on a system with a weak
security can use cu to connect to a more secure system and then install a
Trojan horse on the stronger system. It is apparent that cu should not be
used to go from a weaker system to a stronger one, and it is up to the system
administrator to ensure that this never occurs.
LOCAL AREA NETWORKS
With the increased number of computers operating under the Unix system, some