cyberstrikeus 9.3.4 Disable SSH X11 Forwarding (Scored)
Profile Applicability
- Level 1
Description
The X11Forwarding parameter provides the ability to tunnel X11 traffic through the connection to enable remote graphic connections.
Rationale
Disable X11 forwarding unless there is an operational requirement to use X11 applications directly. There is a small risk that the remote X11 servers of users who are logged in via SSH with X11 forwarding could be compromised by other users on the X11 server. Note that even if X11 forwarding is disabled, users can always install their own forwarders.
Audit Procedure
Using Command Line
To verify the correct SSH setting, run the following command and verify that the output is as shown:
grep "^X11Forwarding" /etc/ssh/sshd_config
Expected Result
X11Forwarding no
Remediation
Using Command Line
Edit the /etc/ssh/sshd_config file to set the parameter as follows:
X11Forwarding no
Default Value
X11Forwarding yes
References
- CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0
Profile
Level 1 - Scored