# NIST SP 800-53 Rev. 5 AC-12(3) — Timeout Warning Message - Source: https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-12-3-timeout-warning-message - Section: [Compliance](https://support.icompaas.com/compliance) › [NIST SP 800-53 Rev. 5 Controls](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5) › AC — Access Control - Last updated: 2026-06-05 - Publisher: iCompaas, Inc. (https://www.icompaas.com) **NIST SP 800-53 Rev. 5**·Control `AC-12(3)`·medium·Component: **Access Control** ## What this control requires > Display a message to users indicating that their session will end in an organization-defined time, prompting them to continue to enhance usability and security awareness. This control supports the Session Management System capability within the Access Control family. > > — NIST SP 800-53 Rev. 5, Control AC-12(3) ### In plain English Display a message to users indicating that their session will end in an organization-defined time, prompting them to continue to enhance usability and security awareness. In practice, this means you can prove you policy management-level controls on a defined cadence. ## Why it matters SP 800-53 is the catalogue every U.S. federal authorisation (FedRAMP, FISMA, CMMC) and most regulated industries point at. A missing control surfaces as a Plan of Action & Milestones (POA&M) item that an Authorizing Official must approve before the Authority To Operate is granted or renewed. ## What an auditor looks for A 3PAO (FedRAMP) or Independent Assessor (NIST RMF) tests against NIST SP 800-53A assessment procedures. For each control they expect a documented implementation that addresses every assessment objective (Examine, Interview, Test) and an implementation summary in the System Security Plan. Within **Access Control**, the assessor will trace your implementation back to the catalogue reference (Control AC-12(3)) 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 - **Policy.** Document the trigger, the owner and the cadence. - **Access.** Document the trigger, the owner and the cadence. - **Security.** Document the trigger, the owner and the cadence. - **Session.** Document the trigger, the owner and the cadence. - **Timeout.** Document the trigger, the owner and the cadence. - **Scope:** management, access control, organization, system, message, time, capability, policy. ## Evidence to collect - **Policy Document.** A signed and version-controlled policy / standard / procedure document. Signed policy or standard documents the safeguard. Focus: Timeout Warning Message. ## 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 800-171 Rev. 3 3.1.5** — Least Privilege](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-1-5-least-privilege) - [**HIPAA (45 CFR Part 164) 164.308(a)(4)(ii)(A)** — Information Access Management - Isolating Healthcare Clearinghouse Functions](https://support.icompaas.com/compliance/hipaa/164-308-a-4-ii-a-information-access-management-isolating-healthcare-clearinghouse) - [**BSI C5:2020 SP-01** — Documentation, communication and provision of policies and instructions](https://support.icompaas.com/compliance/bsi-c5-2020/sp-01-documentation-communication-and-provision-of-policies-and-instructions) - [**India DPDP Act 2023 SE-005** — Information Security Governance, Training & Audit](https://support.icompaas.com/compliance/india-dpdp-act-2023/se-005-information-security-governance-training-audit) ## Related controls in NIST SP 800-53 Rev. 5 - [**Control AC-2(3)** — Disable Accounts](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-2-3-disable-accounts) - [**Control AC-2(2)** — Automated Temporary And Emergency Account Management](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-2-2-automated-temporary-and-emergency-account-management) - [**Control AC-2(5)** — Inactivity Logout](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-2-5-inactivity-logout) - [**Control AC-12(2)** — Termination Message](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-12-2-termination-message) - [**Control AC-16(5)** — Attribute Displays On Objects To Be Output](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-16-5-attribute-displays-on-objects-to-be-output) - [**Control AC-16(6)** — Maintenance Of Attribute Association](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-16-6-maintenance-of-attribute-association) ## References - [NIST Computer Security Resource Center — NIST SP 800-53 Rev. 5](https://csrc.nist.gov/Projects/risk-management/sp800-53-controls) - Catalogue identifier: `Control AC-12(3)` Topics: governance riskawareness trainingpolicy managementsecurity training ## Related compliance guidance - [NIST SP 800-53 Rev. 5: a practical implementation guide for cloud teams](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5): Start with the full NIST SP 800-53 implementation guide — scope, roadmap, evidence and how the assessment runs. - [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): If your obligation is protecting CUI in your own systems for a federal or defence contract, this derived subset — not the full catalogue — is the requirement. - [SOC 2 compliance: a practical implementation guide for cloud-native SaaS teams](https://support.icompaas.com/compliance/soc-2-trust-services-criteria): Most commercial SaaS already hold a SOC 2 Type 2, and FedRAMP 20x Class A is designed for providers that have one.