In this lesson, you will learn how to conduct periodic audits to verify that your active security policies continue to align with your organization’s evolving risk profile.
Even if a Mandatory Access Control (MAC) profile was perfectly hardened during its initial deployment, security efficacy is not a "set-and-forget" metric. Over time, software updates change binary dependencies, and organizational requirements shift. An audit ensures that your policies are not just technically sound, but contextually relevant.
Assessing Policy Relevance
Periodic auditing involves moving beyond simple syntax checks. You must compare your active AppArmor profiles or SELinux policies against current operational logs to identify "policy drift." A policy that was once necessary might now grant excessive privileges due to a change in a service’s functionality, or it might be blocking legitimate traffic that was introduced in a recent feature release.
To evaluate efficacy, compare your denied access attempts against your expected service behaviors. If you see a high volume of denied signals in your logs (e.g., via dmesg or your SIEM), your policy might be causing performance bottlenecks or operational instability. Conversely, if you see zero denied logs for a critical application, you must verify if the profile is actually restrictive enough or if it has become too permissive (a "shadow" policy).
Practical Verification
You can perform a quick audit by analyzing the difference between your policy source code and the actual active kernel state. For example, if you manage profiles with custom automation, run a comparison against the audit logs for a specific timeframe:
# Check audit logs for blocked actions by a specific profile
ausearch -m AVC -ts recent | grep "comm=\"httpd\"" > audit_check.log
# Verify if these denials align with your security requirements
# If they are false positives, refine the policy granularity;
# if they are unexpected behaviors, investigate potential compromise.
By scheduling these reviews—ideally following major application deployments or infrastructure upgrades—you transform security from a static barrier into a dynamic component that grows with your environment.
Key Takeaway: Periodic auditing ensures that security policies remain tightly aligned with organizational requirements by identifying and correcting policy drift through the analysis of actual access patterns.