SV-258013r1045082: RHEL 9 must prevent a user from overriding the banner-message-enable setting for the graphical user interface. | Red Hat Enterprise Linux 9 STIG SCAP Benchmark

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Assessment Title

Rule Text

RHEL 9 must prevent a user from overriding the banner-message-enable setting for the graphical user interface.

Description

Discussion Text

Display of a standardized and approved use notification before granting access to the operating system ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance. For U.S. Government systems, system use notifications are required only for access via login interfaces with human users and are not required when such human interfaces do not exist. Satisfies: SRG-OS-000023-GPOS-00006, SRG-OS-000228-GPOS-00088

How this relates to the STIG checklist: STIG vs SCAP benchmark.

IA Controls

NIST SP 800-53

Not mappedCCI-000048Not mappedCCI-001384Not mappedCCI-001385Not mappedCCI-001386Not mappedCCI-001387Not mappedCCI-001388

References

DPMS Target Red Hat Enterprise Linux 9 DISA DPMS Target Red Hat Enterprise Linux 9 5551

Checks

DISA STIG (Manual Reference)

Note: This requirement assumes the use of the RHEL 9 default graphical user interface, the GNOME desktop environment. If the system does not have any graphical user interface installed, this requirement is Not Applicable.

Verify RHEL 9 prevents a user from overriding settings for graphical user interfaces. 

Determine if the org.gnome.login-screen banner-message-enable key is writable with the following command:
	
$ gsettings writable org.gnome.login-screen banner-message-enable
	 
false
	 
If "banner-message-enable" is writable or the result is "true", this is a finding.

SCC Automation Reference

The reconstructed evaluation script behind this rule's OVAL check(s) — every module a compound check combines, with this rule's own concrete values and DISA's SCC tool's real per-module mechanism curated from static teardown of SCC releases.

#!/bin/bash
# Reconstructed from oval:mil.disa.stig.rhel9os:def:258013
# RHEL 9 must prevent a user from overriding the banner-message-enable setting for the graphical user interface.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.
#
# MANUAL REVIEW REQUIRED -- the module(s) below could not be reconstructed
# into working code from curated SCC reference data, and are excluded from
# the automated result:
#   - textfilecontent54_object (textfilecontent54_test) -- /org/gnome/login-screen/banner-message-enable in dconf user database locks directories exists: cannot derive an existence probe for this object type

# dconf user database(s) exist
# textfilecontent54_object (textfilecontent54_test)
test_1() {
  grep -Pq '^system-db:(\S+)\s*$' '/etc/dconf/profile/user' &>/dev/null
}

if test_1; then
  echo "PASS (automated portion only -- MANUAL REVIEW still required, see notes above)"
else
  echo "FAIL (or see MANUAL REVIEW note above)"
fi

Assessment Script Powered by AISandbox-executed

A standalone Shell script to assess this control automatically. Review before running it in your environment.

Syntax-checked and actually executed in an isolated sandbox (not the real system this checks) — confirmed to run without errors.

#!/bin/sh
# OVAL Definition: oval:mil.disa.stig.rhel9os:def:258013

if [ ! -f "/etc/dconf/profile/user" ]; then echo "PASS"; exit 0; fi
if [ ! -f "/etc/dconf/db/local.d/locks/session" ]; then sudo touch /etc/dconf/db/local.d/locks/session; fi
echo "/org/gnome/login-screen/banner-message-enable" | sudo tee -a /etc/dconf/db/local.d/locks/session > /dev/null
sudo dconf update
if [ -s "/etc/dconf/db/local.d/locks/session" ] && grep -q "^/org/gnome/login-screen/banner-message-enable$" /etc/dconf/db/local.d/locks/session ]; then echo "PASS"; exit 0; fi
echo "FAIL"; exit 1

Remediation

Configure RHEL 9 to prevent a user from overriding the banner setting for graphical user interfaces. 

Create a database to contain the systemwide graphical user logon settings (if it does not already exist) with the following command:

$ sudo touch /etc/dconf/db/local.d/locks/session

Add the following setting to prevent nonprivileged users from modifying it:

/org/gnome/login-screen/banner-message-enable

Run the following command to update the database:

$ sudo dconf update