NIST SP 800-171 Rev. 3 3.9.1 — Personnel Screening

What this control requires

This control requires screening individuals prior to granting access to the system and rescreening them based on organization-defined conditions. The screening assesses an individual's trustworthiness, integrity, and reliability, ensuring that only those who meet the criteria for system access are granted permission, in accordance with applicable laws and regulations. This control supports the Screening Management capability within the Personnel Security (3.9) family.

In plain English

This control requires screening individuals prior to granting access to the system and rescreening them based on organization-defined conditions. 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 high. Auditors expect a named owner, a remediation SLA, and a tooling artefact that evidences continuous operation.

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 Personnel Security, the assessor will trace your implementation back to the catalogue reference (Requirement 3.9.1) 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.
• System. Document the trigger, the owner and the cadence.
• Personnel. Document the trigger, the owner and the cadence.
• Security. Document the trigger, the owner and the cadence.
• Scope: management, security, individuals, personnel.

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.

Identity analytics (Okta, SailPoint, Access Analyzer) demonstrates least-privilege. Focus: Personnel Screening.

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 PS-6(3) — Post-Employment Requirements
• ISO/IEC 27001:2022 A.5.2 — Information security roles and responsibilities
• SOC 2 (2017 TSC) CC1.5 — Accountability for Internal Control Responsibilities
• CIS Controls v8 9.2 — Use DNS Filtering Services
• ISO/IEC 27701:2025 A.3.8 — Identity management

Related controls in NIST SP 800-171 Rev. 3

• Requirement 3.9.2 — Personnel Termination and Transfer
• Requirement 3.2.2 — Role-Based Training
• Requirement 3.1.6 — Least Privilege - Privileged Accounts
• Requirement 3.5.5 — Identifier Management
• Requirement 3.13.4 — Information in Shared System Resources
• Requirement 3.8.2 — Media Access

References

• NIST Computer Security Resource Center — NIST SP 800-171 Rev. 3
• Catalogue identifier: Requirement 3.9.1

Topics: identity accessidentity managementaccess reviewprivileged access