Title

A graphical display manager must not be installed on RHEL 9 unless approved. (Cat II impact)

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 Content

Verify that a graphical user interface is not installed with the following command: $ sudo 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 Text

Document the requirement for a graphical user interface with the ISSO or remove all xorg packages with the following command: Warning: If you are 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

Additional Identifiers

Rule ID: SV-257837r925498_rule

Vulnerability ID: V-257837

Group Title: SRG-OS-000480-GPOS-00227

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.