NIST SP 800-171 Rev. 3 3.1.9 — System Use Notification

What this control requires

This control requires the display of a system use notification message, including privacy and security notices, before granting access to systems that process, store, or transmit Controlled Unclassified Information (CUI). These messages ensure users are aware of applicable security policies and privacy requirements prior to system access. This control supports the System Notification Mechanism capability within the Access Control (3.1) family.

In plain English

This control requires the display of a system use notification message, including privacy and security notices, before granting access to systems that process, store, or transmit Controlled Unclassified Information (CUI). 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.

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 Access Control, the assessor will trace your implementation back to the catalogue reference (Requirement 3.1.9) and look for objective evidence on the latest two assessment cycles.

How to implement

Policy Management

Docs. Keep each policy in version-controlled Markdown alongside the code that implements it; ship a signed PDF snapshot at each annual review and link the SHA into the SoA.

Operational checklist

• Access. Document the trigger, the owner and the cadence.
• Information. Document the trigger, the owner and the cadence.
• System Use. Document the trigger, the owner and the cadence.
• Access Control. Document the trigger, the owner and the cadence.
• Risk. Document the trigger, the owner and the cadence.
• Scope: management, notification, privacy, security notices, store, cui, access control.

Evidence to collect

• Policy Document. A signed and version-controlled policy / standard / procedure document.

Signed policy or standard documents the safeguard. Focus: System Use Notification.

Common pitfalls

• Policies that no engineer has read; the version in Confluence drifts from the version that's actually being enforced.

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 AC-16(5) — Attribute Displays On Objects To Be Output
• HIPAA (45 CFR Part 164) 164.310(a)(2)(iii) — Facility Access Controls - Access Control and Validation Procedures
• SOC 2 (2017 TSC) P3.2 — Consent Management for Personal Information Collection
• ISO/IEC 27001:2022 A.5.1 — Policies for information security
• BSI C5:2020 SP-01 — Documentation, communication and provision of policies and instructions

Related controls in NIST SP 800-171 Rev. 3

• Requirement 3.1.5 — Least Privilege
• Requirement 3.1.20 — Use of External Systems
• Requirement 3.10.7 — Physical Access Control
• Requirement 3.1.2 — Access Enforcement
• Requirement 3.10.2 — Monitoring Physical Access
• Requirement 3.1.10 — Device Lock

References

• NIST Computer Security Resource Center — NIST SP 800-171 Rev. 3
• Catalogue identifier: Requirement 3.1.9

Topics: governance riskpolicy managementprivacy management