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 is configured to boot to the command line:

$ systemctl get-default
multi-user.target

If the system default target is not set to "multi-user.target" and the information system security officer (ISSO) lacks a documented requirement for a graphical user interface, this is a finding.

Fix

Configure OL 9 to boot to the command line.

Set the default target to multi-user with the following command:
$ sudo systemctl set-default multi-user.target

If there is an operational requirement for a graphical user interface, document it with the ISSO.