NIST SP 800-171 Rev. 3 3.1.8 — Unsuccessful Logon Attempts

What this control requires

This control enforces a limit on the number of consecutive invalid logon attempts, followed by an appropriate response such as locking the account, delaying the next logon prompt, or notifying administrators. This mitigates the risk of denial-of-service attacks and unauthorized access attempts, ensuring that actions are tailored to the organization's security policies. This control supports the Login Attempt Control capability within the Access Control (3.1) family.

In plain English

This control enforces a limit on the number of consecutive invalid logon attempts, followed by an appropriate response such as locking the account, delaying the next logon prompt, or notifying administrators. In practice, this means you can prove you account 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 Access Control, the assessor will trace your implementation back to the catalogue reference (Requirement 3.1.8) 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

• Account. Document the trigger, the owner and the cadence.
• Access. Document the trigger, the owner and the cadence.
• Unsuccessful. Document the trigger, the owner and the cadence.
• Access Control. Document the trigger, the owner and the cadence.
• Response. Document the trigger, the owner and the cadence.
• Scope: management, logon attempts, account, security, access control, response.

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 Logon Attempts.

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-7 — Unsuccessful Logon Attempts
• ISO/IEC 27001:2022 A.8.2 — Privileged access rights
• CIS Controls v8 6.7 — Centralize Access Control
• BSI C5:2020 PS-04 — Physical site access control
• SOC 2 (2017 TSC) CC6.2 — Access Provisioning

Related controls in NIST SP 800-171 Rev. 3

• Requirement 3.1.6 — Least Privilege - Privileged Accounts
• Requirement 3.1.7 — Least Privilege - Privileged Functions
• Requirement 3.1.11 — Session Termination
• Requirement 3.1.12 — Remote Access
• Requirement 3.1.1 — Account Management
• Requirement 3.1.22 — Publicly Accessible Content

References

• NIST Computer Security Resource Center — NIST SP 800-171 Rev. 3
• Catalogue identifier: Requirement 3.1.8

Topics: identity accessprivileged accessidentity managementaccess review