AC-7(4)_use-of-alternate-authentication-factor

AC-7(4) Use of Alternate Authentication Factor

Enhancement of: AC-7

High-Level Description

Family: Access Control (AC) Framework: NIST SP 800-53 Rev 5

The use of alternate authentication factors supports the objective of availability and allows a user who has inadvertently been locked out to use additional authentication factors to bypass the lockout.

What to Check

• Verify AC-7(4) Use of Alternate Authentication Factor is documented in SSP
• Validate all 2 control requirements are implemented
• Confirm control is operating effectively
• Review evidence of continuous monitoring for AC-7(4)
• Verify enhancement builds upon base control AC-7

How to Test

Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for AC-7(4) implementation details. Verify the organization has documented how this control is satisfied.

Step 2: Validate Implementation

# For cloud environments, use cloud-audit-mcp tools
# For on-premises, review system configurations directly

# Example: Check if account management policies exist
grep -r "account.management\|access.control" /etc/security/ 2>/dev/null

Step 3: Test Operating Effectiveness

Verify the control is actively functioning, not just documented. Check logs, configurations, and operational evidence.

Tools

Remediation Guide

Control Statement

Allow the use of [organization-defined] that are different from the primary authentication factors after the number of organization-defined consecutive invalid logon attempts have been exceeded; and Enforce a limit of [organization-defined] consecutive invalid logon attempts through use of the alternative factors by a user during a [organization-defined].

Implementation Guidance

The use of alternate authentication factors supports the objective of availability and allows a user who has inadvertently been locked out to use additional authentication factors to bypass the lockout.

Risk Assessment

CWE Categories

References

• NIST SP 800-53 Rev 5 - AC-7(4)
• NIST SP 800-53A Rev 5 (Assessment Procedures)
• NIST SP 800-53 Rev 5 Full Catalog

Checklist

• Control documented in SSP
• Implementation evidence collected
• Operating effectiveness validated
• Continuous monitoring in place
• Related controls (IA-3) reviewed