NIST SP 800-171 Rev. 3 3.5.1 — User Identification and Authentication : iCompaas Support

NIST SP 800-171 Rev. 3·Requirement 3.5.1·critical·Component: Identification and Authentication

What this control requires

This control requires the unique identification and authentication of system users, associating each user with processes acting on their behalf. Additionally, users must be re-authenticated under organization-defined circumstances, such as when roles, credentials, or privileged functions change, or after a defined time period. This control supports the Authentication Management capability within the Identification and Authentication (3.5) family.
— NIST SP 800-171 Rev. 3, Requirement 3.5.1

In plain English

This control requires the unique identification and authentication of system users, associating each user with processes acting on their behalf. In practice, this means you can prove you access management-level controls on a defined cadence.

Why it matters

DoD contractors and their subcontractors must implement all 100 SP 800-171 requirements to keep CUI handling contracts. Gaps are scored against the SPRS scoring methodology; below a 110-point starting score, each unmet requirement deducts points and a below-threshold score can disqualify a bid.

This control is rated critical in the source catalogue. Treat gaps here as production incidents in the risk register, not housekeeping.

What an auditor looks for

A C3PAO conducting a CMMC Level 2 assessment uses NIST SP 800-171A objectives. They expect a System Security Plan (SSP), Plan of Action & Milestones (POA&M) for any gaps, and objective evidence (configurations, ticket records, training records) for every requirement.

Within Identification and Authentication, the assessor will trace your implementation back to the catalogue reference (Requirement 3.5.1) and look for objective evidence on the latest two assessment cycles.

How to implement

Write a short policy stating intent, scope and named owner.
Encode it as a platform guardrail — SCP, Azure Policy initiative, Organisation Policy, or repository policy.
Wire a monitoring signal that catches drift (CSPM rule, SIEM rule, scheduled query, Workspace alert) and ticket it.
Review on a documented cadence and capture the review in the risk register or compliance tracker.

Operational checklist

Access. Document the trigger, the owner and the cadence.
Time. Document the trigger, the owner and the cadence.
System. Document the trigger, the owner and the cadence.
Authentication. Document the trigger, the owner and the cadence.
Risk. Document the trigger, the owner and the cadence.
Scope: management, time, when roles, credentials, authentication.

Evidence to collect

Identity Scan. IAM / IdP exports — Entra ID, Okta, IAM Identity Center, Workspace directory — showing accounts, roles, MFA state and last sign-in.
Policy Document. A signed and version-controlled policy / standard / procedure document.
Infra Scan. Continuous infrastructure-posture telemetry — AWS Config, Azure Policy compliance, GCP Organisation Policy, Wiz / Prisma findings.

Identity analytics (Okta, SailPoint, Access Analyzer) demonstrates least-privilege. Signed policy or standard documents the safeguard. Focus: User Identification and Authentication.

How it maps to other frameworks

Computed from shared tags, control component and key-operation subjects — handy when you are reconciling controls across an audit.

Related controls in NIST SP 800-171 Rev. 3

References

NIST Computer Security Resource Center — NIST SP 800-171 Rev. 3
Catalogue identifier: Requirement 3.5.1

Topics: governance riskidentity accessprivileged accessidentity managementaccess reviewchange management

NIST SP 800-171 Rev. 3 3.5.1 — User Identification and Authentication