The systemd Ctrl-Alt-Delete burst key sequence in RHEL 9 must be disabled.

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.

Satisfies: SRG-OS-000324-GPOS-00125, SRG-OS-000480-GPOS-00227

Verify RHEL 9 is configured to not reboot the system when Ctrl-Alt-Delete is pressed seven times within two seconds with the following command:

$ sudo grep -iR CtrlAltDelBurstAction /etc/systemd/system* /etc/systemd/system.conf.d/55-CtrlAltDel-BurstAction.conf:CtrlAltDelBurstAction=none

If the "CtrlAltDelBurstAction" is not set to "none", is commented out, or is missing, this is a finding.

Configure RHEL 9 to disable the CtrlAltDelBurstAction by adding it to a drop file in a "/etc/systemd/system.conf.d/" configuration file:

If no drop file exists, create one with the following command:

$ sudo mkdir -p /etc/systemd/system.conf.d && sudo vi /etc/systemd/system.conf.d/55-CtrlAltDel-BurstAction.conf

Edit the file to contain the setting by adding the following text:

[Manager] CtrlAltDelBurstAction=none

Reload the daemon for this change to take effect.

$ sudo systemctl daemon-reload