03.01.08 – Unsuccessful Logon Attempts (NIST 800-171 Rev. 3)

2025-06-15

Welcome back to our ongoing series on NIST SP 800-171 Revision 3. Today we’re breaking down Control 03.01.08 – Unsuccessful Logon Attempts, another critical requirement in the Access Control family.

This control is all about detecting suspicious login activity — and stopping it before it becomes a breach.

03.01.08 – Unsuccessful Logon Attempts

Every failed login is a signal. It might be an employee mistyping a password — or it might be a brute-force attack trying to guess credentials.

Systems must be able to detect repeated failures and take action. That means:

• Setting clear limits on failed logins
• Defining a time window for counting attempts
• Automatically locking accounts or alerting admins
• Logging each attempt — and reviewing those logs

Every breach starts somewhere. A failed login could be the first red flag.

03.01.08 – Key Requirements

To comply, organizations must:

• Limit the number of consecutive invalid login attempts
• Define a time period in which those attempts are counted
• Trigger at least one defined action when the limit is exceeded
• Apply consistent settings across all systems
• Log failed logon attempts — and be audit-ready

🚨 DoD-Defined Parameters (Rev. 3)

In Revision 3, the Department of Defense introduced mandatory thresholds that must be enforced:

• SR-03.01.08.a: No more than 5 failed logon attempts allowed within a 5-minute window.

• SR-03.01.08.b: When the threshold is exceeded, systems must trigger one or more of the following:

  • Lock the account or node for at least 15 minutes
  • Or, lock it until manually released — and notify a system administrator

These values are no longer suggestions — they are mandatory compliance minimums that must be reflected in your configurations and access control policy.

03.01.08 – Implementation Tips

Effective implementation includes:

• Configure your login systems with the required thresholds (5 attempts, 5 minutes)
• Define what actions the system takes after a threshold is exceeded (e.g., lockout or admin notification)
• Ensure these settings are applied to all authentication points — not just primary login pages
• Log every failed attempt and review for anomalies
• Include all details in your System Security Plan (SSP)

Organizations may also choose to implement additional protections, like requiring a CAPTCHA, limiting login attempts to specific IP addresses, or adding device-based or time-of-day checks.

🛡️ The only thing worse than five failed login attempts? Not knowing they happened.

03.01.08 – Evidence

During an audit, you should be ready to present:

• System configuration screenshots showing lockout thresholds and periods
• Audit logs of failed logon attempts and triggered actions
• Policy documentation outlining your logon rules and response strategy
• SSP language that aligns with your system behavior
• Confirmation interviews with staff managing access controls

Why it matters..

Most cyberattacks start with a login attempt — or a string of failed ones. This control helps you detect those early warning signs and stop attackers before they get in.

Detect early. Lock fast. Respond with confidence.

• Enforce DoD login limits automatically
• Generate compliance-ready log reports
• Monitor authentication behavior across the enterprise
• Detect brute-force patterns early

Next in our NIST 800-171 Rev. 3 series: 03.01.09 – System Use Notification. We’ll cover login banners, legal notices, and how they protect your organization in both audits and courtrooms.