Ubuntu 24.04 LTS must disable the x86 Ctrl-Alt-Delete key sequence if a graphical user interface is installed.

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

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

$ gsettings get org.gnome.settings-daemon.plugins.media-keys logout @as []

If the "logout" key is bound to an action, is commented out, or is missing, this is a finding.

Configure Ubuntu 24.04 LTS to disable the Ctrl-Alt-Delete sequence when using a graphical user interface.

Create or edit a file named /etc/dconf/db/local.d/00-mediakeys with the following contents:

[org/gnome/settings-daemon/plugins/media-keys] logout=@as []

Update the dconf settings:

$ sudo dconf update