The x86 Ctrl-Alt-Delete key sequence in TOSS must be disabled 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 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.

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

Note: This requirement assumes the use of the TOSS default graphical user interface, Gnome Shell. If the system does not have any graphical user interface installed, this requirement is Not Applicable.

$ sudo grep logout /etc/dconf/db/local.d/*

logout=''

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

Configure the system to disable the Ctrl-Alt-Delete sequence when using a graphical user interface by creating or editing the /etc/dconf/db/local.d/00-disable-CAD file.

Add the setting to disable the Ctrl-Alt-Delete sequence for a graphical user interface:

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

Note: The value above is set to two single quotations.

Then update the dconf settings:

$ sudo dconf update