NIST 800-171 3.3.5: Audit Reduction and Review

What this means

This control requires organizations to establish processes that correlate audit records from multiple sources, analyze them for suspicious patterns, and create standardized reports for investigation and response. The goal is to detect unlawful, unauthorized, suspicious, or unusual activity across your systems in a timely, coordinated manner. Unlike basic log retention, 3.3.5 focuses on active correlation, analysis, and documented response—turning raw logs into actionable intelligence.

How to comply

1. 1.Collect audit logs from all systems, applications, and network devices into a centralized platform or SIEM tool.
2. 2.Define what constitutes suspicious activity for your environment (failed logins, privilege escalation, data exfiltration attempts, etc.).
3. 3.Establish automated alerts and correlations that flag unusual patterns or policy violations in real time.
4. 4.Document your audit review, analysis, and reporting procedures in a written policy.
5. 5.Conduct regular (daily or weekly) manual review of aggregated audit data to catch anomalies automation may miss.
6. 6.Create incident response procedures triggered by audit findings, including investigation steps and escalation paths.
7. 7.Maintain records of all audit analyses, investigations, and responses for compliance demonstration.
8. 8.Review and tune your detection rules and correlations quarterly to reduce false positives and improve accuracy.

Evidence auditors look for

• Centralized log management system (Splunk, ELK, Datadog, or similar) with logs from servers, applications, firewalls, and identity systems.
• Documented audit review and analysis procedure with frequency (e.g., daily automated alerts + weekly manual review).
• Alert configuration rules showing thresholds for suspicious activity (e.g., 5+ failed logins in 10 minutes = alert).
• Sample audit reports showing correlated events, analysis, and findings.
• Incident response tickets or logs demonstrating investigation and remediation of audit findings.
• Written escalation procedures linking audit findings to response teams.
• Evidence of periodic tuning of detection rules (meeting notes, rule change logs).
• Retention policy showing audit logs and analysis records kept for defined period (typically 1+ year).

Frequently asked questions

GRCWatch automates audit log correlation and real-time alert triage, eliminating manual log review work and generating compliance-ready audit reports in minutes—so your team can investigate actual threats instead of managing log sprawl.

See how GRCWatch handles this control automatically

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