MEDIUM RHCOS (Node) M6: Audit Rules - Time Modifications P2

Pending Compare Branch Scanned: 2026-08-12

Remediation required. This group (5 checks) fails on vanilla RHCOS 10.2 and requires MachineConfig remediation. Verified on cnfdt16 (OCP 5.0, RHCOS 10.2) with compliance-operator v1.8.2.

Overview

This remediation configures audit rules to monitor system time modifications, which are critical for maintaining accurate audit logs and detecting tampering.

Settings

Rule	Description
`adjtimex`	Audit fine-grained time adjustments
`clock_settime`	Audit clock setting operations
`settimeofday`	Audit time-of-day changes
`stime`	Audit legacy time setting
`/etc/localtime`	Watch for localtime file changes

Implementation

apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
metadata:
  name: 75-audit-time-medium
  labels:
    machineconfiguration.openshift.io/role: master
spec:
  config:
    ignition:
      version: 3.2.0
    storage:
      files:
        - path: /etc/audit/rules.d/75-time-change.rules
          mode: 0644
          overwrite: true
          contents:
            inline: |
              ## Time change monitoring
              -a always,exit -F arch=b64 -S adjtimex -S settimeofday -k time-change
              -a always,exit -F arch=b32 -S adjtimex -S settimeofday -S stime -k time-change
              -a always,exit -F arch=b64 -S clock_settime -k time-change
              -a always,exit -F arch=b32 -S clock_settime -k time-change
              -w /etc/localtime -p wa -k time-change

Compliance Checks Remediated

Check	Profile	Docs
`rhcos4-e8-worker-audit-rules-time-adjtimex`	E8	📖
`rhcos4-e8-worker-audit-rules-time-clock-settime`	E8	📖
`rhcos4-e8-worker-audit-rules-time-settimeofday`	E8	📖
`rhcos4-e8-worker-audit-rules-time-stime`	E8	📖
`rhcos4-e8-worker-audit-rules-time-watch-localtime`	E8	📖

Source Remediation Files (5)

medium/rhcos4-e8-worker-audit-rules-time-adjtimex.yaml
medium/rhcos4-e8-worker-audit-rules-time-clock-settime.yaml
medium/rhcos4-e8-worker-audit-rules-time-settimeofday.yaml
medium/rhcos4-e8-worker-audit-rules-time-stime.yaml
medium/rhcos4-e8-worker-audit-rules-time-watch-localtime.yaml

Security Impact

Time modification auditing is critical because:

Attackers may alter time to invalidate security certificates
Time changes can corrupt audit log sequencing
Accurate timestamps are essential for forensic analysis

Upstream Proposal

The following changes could eliminate the need for MachineConfig remediation. Items are categorized by recommended scope:

Time modification audit rules (5 syscalls) RAN Low

openshift/os /etc/audit/rules.d/50-time-change.rules

Tracks time changes that could be used to manipulate log timestamps for forensic evasion.
Scope: Time change auditing matters for forensic integrity but adds log volume on all nodes.

PR History

Time modification audit rules (5 syscalls) Not Filed blocked

coreos/rhel-coreos-config

Audit rules are compliance monitoring policies, not security defaults. RHCOS ships no audit rules in rules.d by default — only samples in /usr/share/audit/sample-rules/ that Red Hat explicitly warns are 'not exhaustive nor up to date.' CoreOS maintainers debated whether to include the audit RPM at all (fedora-coreos-tracker#461) and called it 'an odd fit' (coreos/bugs#140). Audit messages already flood console on fresh boot (fedora-coreos-tracker#220). Deploying rules in the base image would substantially increase audit volume for all RHCOS deployments. The Compliance Operator's MachineConfig remediation model is the intended deployment path.

coreos/fedora-coreos-tracker/issues/461 coreos/fedora-coreos-tracker/issues/220 coreos/bugs/issues/140 docs.redhat.com/en/documentation/red_hat_enterprise_linux/9/html/security_hardening/auditing-the-system_security-hardening

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