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The Ubuntu Operating system must disable the x86 Ctrl-Alt-Delete key sequence.


Finding ID Version Rule ID IA Controls Severity
V-219212 UBTU-18-010151 SV-219212r832928_rule High
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.
Canonical Ubuntu 18.04 LTS Security Technical Implementation Guide 2022-12-06


Check Text ( C-20937r832926_chk )
Verify the Ubuntu operating system is not configured to reboot the system when Ctrl-Alt-Delete is pressed.

Check that the "ctrl-alt-del.target" (otherwise also known as reboot.target) is not active with the following command:

$ sudo systemctl status ctrl-alt-del.target
Loaded: masked (/dev/null; bad)
Active: inactive (dead)

If the "ctrl-alt-del.target" is not masked, this is a finding.
Fix Text (F-20936r832927_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

And reload the daemon to take effect:

$ sudo systemctl daemon-reload