Rule ID
SV-233308r991589_rule
Version
V3R2
CCIs
When X11 forwarding is enabled, there may be additional exposure to the server and client displays if the sshd proxy display is configured to listen on the wildcard address. By default, sshd binds the forwarding server to the loopback address and sets the hostname part of the DIPSLAY environment variable to localhost. This prevents remote hosts from connecting to the proxy display.
Verify the SUSE operating system SSH daemon prevents remote hosts from connecting to the proxy display.<br /><br />Check the SSH X11UseLocalhost setting with the following command:<br /><br /># sudo grep -i x11uselocalhost /etc/ssh/sshd_config<br />X11UseLocalhost yes<br /><br />If the "X11UseLocalhost" keyword is set to "no", is missing, or is commented out, this is a finding.
Configure the SUSE operating system SSH daemon to prevent remote hosts from connecting to the proxy display.<br /><br />Edit the "/etc/ssh/sshd_config" file to uncomment or add the line for the "X11UseLocalhost" keyword and set its value to "yes" (this file may be named differently or be in a different location if using a version of SSH that is provided by a third-party vendor):<br /><br />X11UseLocalhost yes