The x86 Ctrl-Alt-Delete key sequence in the Ubuntu operating system must be disabled if GNOME is installed.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-80957	UBTU-16-010631	SV-95669r1_rule		High

Description
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 GNOME 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.

Description

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 GNOME 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.

STIG	Date
Canonical Ubuntu 16.04 LTS Security Technical Implementation Guide	2018-07-18

Details

Check Text ( C-80715r1_chk )
Verify the Ubuntu operating system is not configured to reboot the system when Ctrl-Alt-Delete is pressed when using GNOME. Check that the "logout" target is not bound to an action with the following command: # 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.

Fix Text (F-87833r1_fix)
Configure the system to disable the Ctrl-Alt-Delete sequence when using GNOME 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 GNOME: [org/gnome/settings-daemon/plugins/media-keys] logout=’’ Then update the dconf settings: # dconf update