Vulnerability Discussion

Unnecessary service packages must not be installed to decrease the attack surface of the system. Graphical display managers have a long history of security vulnerabilities and must not be used, unless approved and documented.

Check

Verify that OL 9 does not have a graphical user interface installed with the following command:

$ dnf list --installed "xorg*common"
Error: No matching Packages to list

If the "x11-server-common" package is installed, and the use of a graphical user interface has not been documented with the information system security officer (ISSO) as an operational requirement, this is a finding.

Fix

Remove all xorg packages with the following command:

Warning: If accessing the system through the graphical user interface, change to the multi-user.target with the following command:

$ sudo systemctl isolate multi-user.target

Warning: Removal of the graphical user interface will immediately render it useless. The following commands must not be run from a virtual terminal emulator in the graphical interface.

$ sudo dnf remove "xorg*"
$ sudo systemctl set-default multi-user.target

If there is an operational requirement for a graphical user interface it must be documented with the ISSO.