NIST 800-53 REV 5 • AUDIT AND ACCOUNTABILITY
AU-7 — Audit Record Reduction and Report Generation
Provide and implement an audit record reduction and report generation capability that: Supports on-demand audit record review, analysis, and reporting requirements and after-the-fact investigations of incidents; and Does not alter the original content or time ordering of audit records.
Supplemental Guidance
Audit record reduction is a process that manipulates collected audit log information and organizes it into a summary format that is more meaningful to analysts. Audit record reduction and report generation capabilities do not always emanate from the same system or from the same organizational entities that conduct audit logging activities. The audit record reduction capability includes modern data mining techniques with advanced data filters to identify anomalous behavior in audit records. The report generation capability provided by the system can generate customizable reports. Time ordering of audit records can be an issue if the granularity of the timestamp in the record is insufficient.
Practitioner Notes
Your audit system must be able to reduce large volumes of log data into useful summaries and generate reports that support after-the-fact investigation. Raw logs are not enough.
Example 1: In Splunk, create saved searches and dashboards that summarize key metrics: top authentication failures by user, top denied firewall connections by source IP, and privileged account usage trends. These summaries turn millions of events into actionable views.
Example 2: In Microsoft Sentinel, use KQL (Kusto Query Language) to create custom queries that aggregate and filter log data. Create an investigation workbook that lets analysts enter a username or IP address and see all related activity across all log sources — sign-ins, file access, email, network connections — filtered and correlated.