NIST SP 800-53 Rev. 5 AC-11 — Device Lock

What this control requires

Initiate a device lock after an organization-defined period of inactivity or require user-initiated locks before leaving systems unattended, retaining the lock until re-authentication. This control supports the Operating System capability within the Access Control family.

In plain English

Initiate a device lock after an organization-defined period of inactivity or require user-initiated locks before leaving systems unattended, retaining the lock until re-authentication. In practice, this means you can prove you inactivity 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-11) and look for objective evidence on the latest two assessment cycles.

How to implement

Endpoint Protection

MDM. Make MDM enrollment a hard gate for device access (Intune compliance + Conditional Access, or Jamf + Okta device trust). Unmanaged devices simply don't get a session token.

EDR. Deploy CrowdStrike / SentinelOne / Defender for Endpoint to every server and laptop; alert on any host that stops sending telemetry for >24h.

Operational checklist

• Inactivity. Document the trigger, the owner and the cadence.
• Access. Document the trigger, the owner and the cadence.
• Review. Document the trigger, the owner and the cadence.
• Device. Document the trigger, the owner and the cadence.
• Protection. Document the trigger, the owner and the cadence.
• Scope: management, access control, authentication, organization, system, lock, protection, identity.

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: Device Lock.

Common pitfalls

• Pilot MDM rollouts that quietly exclude executives or engineers; carving out the highest-risk users is the most common audit failure.

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 3.1.10 — Device Lock
• CIS Controls v8 6.7 — Centralize Access Control
• BSI C5:2020 PS-04 — Physical site access control
• SOC 2 (2017 TSC) CC6.4 — Physical Access Controls
• ISO/IEC 27001:2022 A.8.2 — Privileged access rights

Related controls in NIST SP 800-53 Rev. 5

• Control AC-10 — Concurrent Session Control
• Control AC-5 — Separation Of Duties
• Control AC-9(4) — Additional Logon Information
• Control AC-7 — Unsuccessful Logon Attempts
• Control AC-14 — Permitted Actions Without Identification Or Authentication
• Control AC-6(6) — Privileged Access By Non-Organizational Users

References

• NIST Computer Security Resource Center — NIST SP 800-53 Rev. 5
• Catalogue identifier: Control AC-11

Topics: identity accessidentity managementaccess reviewprivileged accessendpoint protection