NIST SP 800-53 Rev. 5 AC-9(1) — Unsuccessful Logons

What this control requires

Notify users upon successful system logon of the number of unsuccessful logon attempts since their last successful logon to help identify potential unauthorized access attempts. This control supports the Authentication System capability within the Access Control family.

In plain English

Notify users upon successful system logon of the number of unsuccessful logon attempts since their last successful logon to help identify potential unauthorized access attempts. In practice, this means you can prove you access 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-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.
• Review. Document the trigger, the owner and the cadence.
• Unsuccessful. Document the trigger, the owner and the cadence.
• Successful. Document the trigger, the owner and the cadence.
• Authentication. Document the trigger, the owner and the cadence.
• Scope: management, access control, authentication, system, logon attempts, logons, unsuccessful logons, 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: Unsuccessful Logons.

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 3.1.8 — Unsuccessful Logon Attempts
• CIS Controls v8 6.7 — Centralize Access Control
• BSI C5:2020 PS-04 — Physical site access control
• ISO/IEC 27001:2022 A.8.2 — Privileged access rights
• SOC 2 (2017 TSC) CC6.1 — Logical Access Controls

Related controls in NIST SP 800-53 Rev. 5

• Control AC-9(2) — Successful And Unsuccessful Logons
• Control AC-7 — Unsuccessful Logon Attempts
• Control AC-7(4) — Use Of Alternate Authentication Factor
• Control AC-9 — Previous Logon Notification
• 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-9(1)

Topics: identity accessidentity managementaccess reviewprivileged access