Vulnerability Discussion

A locally logged-on user who presses Ctrl-Alt-Delete in quick succession when at the console can reboot the system.

If accidentally pressed, as could happen in the case of a mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot.

In a graphical user environment, risk of unintentional reboot from the Ctrl-Alt-Delete sequence is reduced because the user will be prompted before any action is taken.

Check

Verify AlmaLinux OS 9 is configured to not reboot the system when Ctrl-Alt-Delete is pressed seven times within two seconds with the following command:

$ systemd-analyze cat-config systemd/system.conf | grep -v '#' | grep CtrlAltDel

CtrlAltDelBurstAction=none

If "CtrlAltDelBurstAction" is not set to "none", is commented out, or is missing, this is a finding.

Fix

Configure the system to disable the CtrlAltDelBurstAction by added or modifying the following line in the "/etc/systemd/system.conf" configuration file:

CtrlAltDelBurstAction=none

Reload the daemon for this change to take effect.

$ systemctl daemon-reexec