# NIST SP 800-171 Rev. 3 3.5.1 — User Identification and Authentication - Source: https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-5-1-user-identification-and-authentication - Section: [Compliance](https://support.icompaas.com/compliance) › [NIST SP 800-171 Rev. 3 Requirements](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3) › Identification and Authentication — §3.5 - Last updated: 2026-06-05 - Publisher: iCompaas, Inc. (https://www.icompaas.com) **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 1. Write a short policy stating intent, scope and named owner. 2. Encode it as a platform guardrail — SCP, Azure Policy initiative, Organisation Policy, or repository policy. 3. Wire a monitoring signal that catches drift (CSPM rule, SIEM rule, scheduled query, Workspace alert) and ticket it. 4. 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. - [**NIST SP 800-53 Rev. 5 IA-11** — Re-Authentication](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ia-11-re-authentication) - [**ISO/IEC 27001:2022 A.5.16** — Identity management](https://support.icompaas.com/compliance/iso-27001-2022/a-5-16-identity-management) - [**CIS Controls v8 6.1** — Establish an Access Granting Process](https://support.icompaas.com/compliance/cis-controls-v8/6-1-establish-an-access-granting-process) - [**SOC 2 (2017 TSC) CC6.2** — Access Provisioning](https://support.icompaas.com/compliance/soc-2-trust-services-criteria/cc6-2-access-provisioning) - [**BSI C5:2020 IDM-02** — Granting and change of user accounts and access rights](https://support.icompaas.com/compliance/bsi-c5-2020/idm-02-granting-and-change-of-user-accounts-and-access-rights) ## Related controls in NIST SP 800-171 Rev. 3 - [**Requirement 3.5.4** — Replay-Resistant Authentication](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-5-4-replay-resistant-authentication) - [**Requirement 3.5.5** — Identifier Management](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-5-5-identifier-management) - [**Requirement 3.5.3** — Multi-Factor Authentication](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-5-3-multi-factor-authentication) - [**Requirement 3.5.7** — Password Management](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-5-7-password-management) - [**Requirement 3.5.12** — Authenticator Management](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-5-12-authenticator-management) - [**Requirement 3.1.6** — Least Privilege - Privileged Accounts](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-1-6-least-privilege-privileged-accounts) ## References - [NIST Computer Security Resource Center — NIST SP 800-171 Rev. 3](https://csrc.nist.gov/pubs/sp/800/171/r3/final) - Catalogue identifier: `Requirement 3.5.1` Topics: governance riskidentity accessprivileged accessidentity managementaccess reviewchange management ## Related compliance guidance - [NIST SP 800-171 and CMMC: a practical guide to protecting CUI in the cloud](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3): Start with the full NIST SP 800-171 implementation guide — scope, roadmap, evidence and how the assessment runs. - [NIST SP 800-53 Rev. 5: a practical implementation guide for cloud teams](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5): The catalogue 800-171 is tailored from, and the basis of the FedRAMP Moderate baseline your cloud providers must meet for CUI. - [ISO/IEC 27001:2022 compliance: a practical implementation guide](https://support.icompaas.com/compliance/iso-27001-2022): If commercial customers ask for a certificate as well, most 800-171 controls can be evidenced once and mapped to Annex A.