Vulnerability Discussion
Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended.
Check
Verify that RHEL 9 logs out sessions that are idle for 15 minutes with the following command:
$ sudo grep -i ^StopIdleSessionSec /etc/systemd/logind.conf
StopIdleSessionSec=900
If "StopIdleSessionSec" is not configured to "900" seconds, this is a finding.
Fix
Configure RHEL 9 to log out idle sessions by editing the /etc/systemd/logind.conf file with the following line:
StopIdleSessionSec=900
The "logind" service must be restarted for the changes to take effect. To restart the "logind" service, run the following command:
$ sudo systemctl restart systemd-logind