SV-257805r1044856: RHEL 9 must be configured to disable the Controller Area Network kernel module. | Red Hat Enterprise Linux 9 STIG SCAP Benchmark

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Assessment Title

Rule Text

RHEL 9 must be configured to disable the Controller Area Network kernel module.

Description

Discussion Text

Disabling Controller Area Network (CAN) protects the system against exploitation of any flaws in its implementation.

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

IA Controls

NIST SP 800-53

Not mappedCCI-000381

References

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

Checks

DISA STIG (Manual Reference)

Verify that RHEL 9 disables the ability to load the CAN kernel module with the following command:

$ grep -r can /etc/modprobe.conf /etc/modprobe.d/* 

install can /bin/false
blacklist can

If the command does not return any output, or the lines are commented out, and use of CAN is not documented with the information system security officer (ISSO) as an operational requirement, 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:257805
# RHEL 9 must be configured to disable the Controller Area Network kernel module.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# /etc/modprobe.d contains a file that contains 'blacklist can'
# textfilecontent54_object (textfilecontent54_test)
test_1() {
  grep -rqP --include='*' '^[ \t]*blacklist[ \t]+can[ \t]*$' '/etc/modprobe.d' &>/dev/null
}

if test_1; then
  echo "PASS"
else
  echo "FAIL"
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
# DISA STIG RHEL 9 must be configured to disable the Controller Area Network kernel module - oval:mil.disa.stig.rhel9os:def:257805
if [ -e /etc/modprobe.d/can.conf ]; then \
    grep -q "^[ \t]*blacklist[ \t]+can[ \t]*$" /etc/modprobe.d/can.conf && echo "PASS"; exit 0; \
else echo "FAIL"; exit 1; fi

Remediation

To configure the system to prevent the can kernel module from being loaded, add the following lines to the file  /etc/modprobe.d/can.conf (or create can.conf if it does not exist):

install can /bin/false
blacklist can