NIST 800-171 3.3.1 (AU.L2-3.3.1): System Audit Logs

Create and retain system audit logs and records to the extent needed to enable the monitoring, analysis, investigation, and reporting of unlawful or unauthorized system activity.

NIST SP 800-171 Rev. 2, requirement 3.3.1

CMMC Level 2 practice AU.L2-3.3.1Published 2026-11-11

What 3.3.1 means in practice

Decide which events matter (sign-ins, privilege use, changes, access to CUI), make sure every system records them with enough detail to investigate, and keep the records long enough to use. Assessors check both the list of event types and real logs that contain them.

SPRS points and the CMMC POA&M

CMMC Level 2 practice: AU.L2-3.3.1
SPRS points: 5 points. When it is not met, the DoD Assessment Methodology subtracts 5 from the score of 110.
CMMC POA&M: Not allowed. It is worth 5 points, and 32 CFR 170.21(a)(2)(ii) admits only requirements worth 1 point, with one exception: 3.13.11 when encryption is used but not FIPS validated.

Sources: NIST SP 800-171 DoD Assessment Methodology, version 1.2.1 (June 24, 2020), Annex A; 32 CFR 170.21, Plan of Action and Milestones requirements.

What an assessor checks for 3.3.1

NIST SP 800-171A gives 6 determination statements for 3.3.1, each found satisfied or other than satisfied. Determine if:

3.3.1[a] audit logs needed (i.e., event types to be logged) to enable the monitoring, analysis, investigation, and reporting of unlawful or unauthorized system activity are specified.
3.3.1[b] the content of audit records needed to support monitoring, analysis, investigation, and reporting of unlawful or unauthorized system activity is defined.
3.3.1[c] audit records are created (generated).
3.3.1[d] audit records, once created, contain the defined content.
3.3.1[e] retention requirements for audit records are defined.
3.3.1[f] audit records are retained as defined.

NIST SP 800-171A (June 2018), assessment objectives for 3.3.1

Evidence that shows 3.3.1 is met

The list of event types to log and the content each record must hold.
Logging configuration for the identity provider, servers, network devices and cloud services.
Sample audit records showing the defined content.
The retention period and the storage settings that enforce it.

How PolicyCortex gathers the evidence

PolicyCortex reads this evidence with the collectors below, read only, and grades 3.3.1 from it. Each line says what the product checks.

Azure Monitor: Diagnostic settings. Checks that diagnostic settings capture the sign-in and audit log categories and send them to a Log Analytics workspace.
AWS: CloudTrail and CloudWatch. Checks that CloudTrail is on in every region, delivers to CloudWatch Logs and records S3 data events.
AWS: S3 buckets · EC2 and VPC networking · Data stores · Load balancers, API Gateway, CloudFront and Lambda. Checks that S3 server access logging, VPC flow logs, RDS log exports, and load balancer, API Gateway and CloudFront logging are turned on.

Related pages

Calculator: SPRS score calculator: mark 3.3.1 and the other 109 requirements and see the score.
Sample package: Sample package: an SSP, a POA&M and an evidence chain the product generated from demonstration data.
Family: All 9 Audit and Accountability requirements (3.3).
Previous: 3.2.3: Insider Threat
Next: 3.3.2: User Accountability
All requirements: All 110 NIST SP 800-171 requirements, by family.

Related records

Guides and articles describe the work. The evidence that work produces is described in three proof pages, the architecture page, and the two pages on authorization.

proof.state: Proof of State. What the environment was, as of a date someone else picks: point-in-time records, content hashed and chained.
proof.change: Proof of Change. Who or what altered the environment, under what authority, with before and after state hashes.
proof.agency: Proof of Agency. What a machine was permitted to do before it acted, what it did, and what would have stopped it.
architecture: Architecture. How the chain is built and where the evidence is stored in each delivery mode.
authorization: Continuous ATO. How an authorizing official's decision is recorded with its package, and how the authorized system is checked against it every hour.
baseline: NIST SP 800-53. The Low, Moderate and High baselines as evidence, with the SSP, SAR and POA&M generated from one record.