Vulnerability Discussion

Internet services not required for system or application processes must not be active 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 the system 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.

Verify that a graphical user interface is not installed:

$ rpm -qa | grep xorg | grep server

Ask the System Administrator if use of a graphical user interface is an operational requirement.

If the use of a graphical user interface on the system is not documented with the ISSO, this is a finding.

Fix

Document the requirement for a graphical user interface with the ISSO or reinstall the operating system without the graphical user interface. If reinstallation is not feasible, then continue with the following procedure:

Open an SSH session and enter the following commands:

$ sudo systemctl set-default multi-user.target

$ sudo yum remove xorg-x11-server-Xorg xorg-x11-server-common xorg-x11-server-utils

A reboot is required for the changes to take effect.