NIST 800-171 3.5.1 (IA.L2-3.5.1): Identification

Identify system users, processes acting on behalf of users, and devices.

NIST SP 800-171 Rev. 2, requirement 3.5.1

CMMC Level 2 practice IA.L2-3.5.1Published 2026-11-11

What 3.5.1 means in practice

Every user, service process and device gets its own identifier, so the system always knows who or what is acting. Shared logins for interactive use defeat this, and so do service accounts that nobody can tie to an application and an owner.

SPRS points and the CMMC POA&M

CMMC Level 2 practice: IA.L2-3.5.1
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 3.5.1

NIST SP 800-171A gives 3 determination statements for 3.5.1, each found satisfied or other than satisfied. Determine if:

3.5.1[a] system users are identified.
3.5.1[b] processes acting on behalf of users are identified.
3.5.1[c] devices accessing the system are identified.

NIST SP 800-171A (June 2018), assessment objectives for 3.5.1

Evidence that shows 3.5.1 is met

The procedure for issuing identifiers to users, service accounts and devices.
A list of service accounts and managed identities, each with the application it runs and its owner.
Device identity records, such as directory objects or device management enrollments.

How PolicyCortex gathers the evidence

No PolicyCortex collector reads the evidence for 3.5.1. Your team provides the evidence listed above.

Related pages

Calculator: SPRS score calculator: mark 3.5.1 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 11 Identification and Authentication requirements (3.5).
Previous: 3.4.9: User-Installed Software
Next: 3.5.2: Authentication
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.