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# Audit Logging for CMMC: What the AU Controls Really Expect
- URL: https://www.cmmcoperator.com/audit-logging-for-cmmc-what-the-au-controls-really-expect/
- Published: 2026-08-15T14:18:38.000Z
- Updated: 2026-08-15T14:18:38.000Z
- Author: HydratedSec
- Tags: CMMC, NIST 800-171, Audit Logging, CMMC Level 2

Logging is one of those CMMC areas where contractors are technically doing something but not the right thing. Systems generate logs by default, so it feels covered. But the Audit and Accountability family asks for more than logs existing. It asks that you decide what to capture, protect it, review it, and be able to reconstruct what happened after an event. Logs you never look at do not satisfy the control, and they will not help you during an incident either.

## What the AU Family Asks For

The Audit and Accountability controls in NIST SP 800-171 work together. You define which events are auditable, create records with enough detail to trace activity to a specific user, protect the logs from tampering, review and analyze them, and alert on audit failures. The thread running through all of it is accountability: when something happens in your CUI environment, you should be able to answer who did what, when, and from where.

## What Your Logs Need to Capture

An auditable event record should be specific enough to reconstruct activity. At minimum, capture:

- Successful and failed logon attempts, including the account and source.
- Privileged actions, account changes, and permission modifications.
- Access to CUI and changes to security-relevant configuration.
- Timestamps from a synchronized, authoritative time source so events line up across systems.

## The Part Most People Skip: Review

Collecting logs is the half that tools do for you. Reviewing them is the half that proves the control. The AU family expects regular analysis, not just retention. For a small contractor, a centralized log destination, even a modest one, makes this practical: pull logs from your endpoints, identity provider, and CUI systems into one place, set alerts for high-signal events like repeated failed logons or privilege changes, and document a recurring review cadence. Then keep the evidence that the review actually happens, because review you cannot demonstrate is the same as no review at all in an assessment.

Protect the logs themselves too. If an attacker or a careless admin can edit or delete audit records, the trail is worthless, which is why the controls call for restricting and safeguarding audit information.

## Audit Logging Readiness Checklist

- Define your list of auditable events across the CUI environment.
- Centralize logs from endpoints, identity, and CUI systems into one destination.
- Synchronize time across systems to an authoritative source.
- Set alerts for high-signal events and for audit logging failures.
- Restrict and protect log access so records cannot be altered or deleted.
- Document a recurring review cadence and keep evidence that reviews occur.

CMMC Operator provides compliance readiness resources for informational and planning purposes only. This article is not legal advice, an assessment determination, or a substitute for a qualified C3PAO or GRC advisor. Validate your audit logging approach against the current NIST SP 800-171 Audit and Accountability requirements and your own environment.