SV-288816r1261438: Ubuntu 24.04 LTS audit system must protect auditing rules from unauthorized change. | Canonical Ubuntu 22.04 LTS STIG SCAP Benchmark

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Assessment Title

Rule Text

Ubuntu 24.04 LTS audit system must protect auditing rules from unauthorized change.

Description

Discussion Text

Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality. Audit information includes all information (e.g., audit records, audit settings, audit reports) needed to successfully audit Ubuntu 24.04 LTS system activity. In immutable mode, unauthorized users cannot execute changes to the audit system to potentially hide malicious activity and then put the audit rules back. A system reboot would be noticeable, and a system administrator could then investigate the unauthorized changes.

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

IA Controls

NIST SP 800-53

Not mappedCCI-000163

References

DPMS Target Canonical Ubuntu 22.04 LTS DISA DPMS Target Canonical Ubuntu 22.04 LTS 5594

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.ubuntu2204os:def:288816
# Ubuntu 24.04 LTS audit system must protect auditing rules from unauthorized change.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# /etc/audit/rules.d/*.rules: -e 2 option is present and is the last line in the file
# textfilecontent54_object (textfilecontent54_test)
test_1() {
  grep -rqP --include='*.rules' '\n[ \t]*-e[ \t]+2\s*$' '/etc/audit/rules.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
# OVAL Definition: oval:mil.disa.stig.ubuntu2204os:def:288816
if [ ! -d "/etc/audit/rules.d" ]; then echo "PASS"; exit 0; fi
for file in /etc/audit/rules.d/*.rules; do
    if [ -s "$file" ]; then
        if grep -q '^[ \t]*-e[ \t]+2$' "$file" && grep -q '^[ \t]*-e[ \t]+2$' "$file" | grep -q '$'; then
            echo "PASS"; exit 0
        fi
    fi
done
echo "FAIL"; exit 1

Remediation

Configure the audit system to set the audit rules to be immutable by performing the following steps:

Create or edit a finalized rules file (e.g., "/etc/audit/rules.d/99-finalize.rules") and append the following option as the absolute last line:

-e 2

Compile and load the new rules into the active kernel:

$ sudo augenrules --load

Note: Once this rule is active, further changes to the audit configuration will be blocked. A system reboot will be required to apply any future audit rule modifications.