Developing a Security Incident Response Plan

Create an incident response plan centered around the analysis of MAC log data.

In this lesson, you will learn how to structure a Security Incident Response Plan (SIRP) specifically tailored to analyze Mandatory Access Control (MAC) log data during a breach.

When a security incident occurs, your MAC logs (such as AppArmor or SELinux denials) are your most reliable indicators of compromise. While standard system logs might show an attacker has logged in, MAC logs show exactly what the attacker tried to do but was prevented from achieving. A robust response plan must treat these denials as the primary signal for triage.

The Anatomy of a MAC-Centric SIRP

Your incident response plan should follow a "Contain, Analyze, Reconstruct" workflow centered on your MAC audit stream:

Detection via Denial Spike: Set up alerts for high-frequency MAC denials. A sudden flood of denied messages for a specific process or user context is an early warning that an exploit is attempting to traverse your hard boundaries.
Context Extraction: When an alert triggers, extract the specific security context from the audit log. For example, in an AppArmor scenario, you would filter your logs using grep to identify the restricted profile under stress:
```
grep "apparmor=\"DENIED\"" /var/log/audit/audit.log | grep "name=\"/usr/sbin/httpd\"" > incident_httpd_denials.log
```
Behavioral Reconstruction: Analyze the captured denials. Are they attempting to access sensitive /etc/ files, or are they attempting to execute unauthorized network syscalls? By mapping these denials against your established security policy, you can determine if the attacker is probing for a policy bypass or if an application has simply drifted from its expected behavior.
Policy-Driven Containment: Once the attack vector is understood, your SIRP should dictate an immediate "deny-all" update to the implicated security context. Use your orchestration tools to propagate a restrictive profile update to other nodes, effectively quarantining the threat across your fleet.

By centering your response plan on MAC logs, you shift the focus from guessing what an attacker did to observing the hard walls they hit. This prevents the "analysis paralysis" common during high-pressure incidents.

Key Takeaway: An effective incident response plan treats MAC denial logs as the ground truth for identifying breach attempts and orchestrating immediate containment.