NIST 800-171 3.5.2 (IA.L2-3.5.2): Authentication

Authenticate (or verify) the identities of users, processes, or devices, as a prerequisite to allowing access to organizational systems.

NIST SP 800-171 Rev. 2, requirement 3.5.2

CMMC Level 2 practice IA.L2-3.5.2Published 2026-11-11

What 3.5.2 means in practice

Identity has to be proven before access is granted, for people, for processes and for devices. Passwords with multifactor authentication for people, certificates or managed credentials for services, and device certificates or compliance checks for machines are the usual means; stale or never-rotated credentials weaken every one of them.

SPRS points and the CMMC POA&M

CMMC Level 2 practice: IA.L2-3.5.2
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 3.5.2

NIST SP 800-171A gives 3 determination statements for 3.5.2, each found satisfied or other than satisfied. Determine if:

3.5.2[a] the identity of each user is authenticated or verified as a prerequisite to system access.
3.5.2[b] the identity of each process acting on behalf of a user is authenticated or verified as a prerequisite to system access.
3.5.2[c] the identity of each device accessing or connecting to the system is authenticated or verified as a prerequisite to system access.

NIST SP 800-171A (June 2018), assessment objectives for 3.5.2

Evidence that shows 3.5.2 is met

Authentication settings for each access path: identity provider, VPN, servers and applications.
How service accounts and processes authenticate, such as certificates, managed identities or rotated keys.
Device authentication settings, such as certificate-based network access or device compliance checks.

How PolicyCortex gathers the evidence

PolicyCortex reads this evidence with the collectors below, read only, and grades 3.5.2 from it. Each line says what the product checks.

AWS: IAM. Checks that active IAM access keys are rotated within 90 days, flags credentials unused for 90 days, and checks that the root account has no access keys.

Related pages

Calculator: SPRS score calculator: mark 3.5.2 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: 3.5.1: Identification
Next: 3.5.3: Multifactor 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.