Vulnerability Discussion

A locally logged-on user who presses Ctrl-Alt-Delete, 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.

Check

Verify Ubuntu 24.04 LTS is not configured to reboot the system when Ctrl-Alt-Delete is pressed with the following command:

$ systemctl status ctrl-alt-del.target
o ctrl-alt-del.target
Loaded: masked (Reason: Unit ctrl-alt-del.target is masked.)
Active: inactive (dead)

If the "ctrl-alt-del.target" is not masked, this is a finding.

Fix

Configure the system to disable the Ctrl-Alt-Delete sequence for the command line with the following commands:

$ sudo systemctl disable ctrl-alt-del.target
[...]

$ sudo systemctl mask ctrl-alt-del.target
Created symlink /etc/systemd/system/ctrl-alt-del.target ? /dev/null.

Reload the daemon to take effect:

$ sudo systemctl daemon-reload