Level 2 · Identification and Authentication
IA.L2-3.5.4
Replay-Resistant Authentication
Replay resistance concerns whether captured authentication information can be reused to obtain access.
Official reference
The requirement
Employ replay-resistant authentication mechanisms for network access to privileged and non-privileged accounts.
DoD CMMC Assessment Guide, Level 2, version 2.13. IA.L2-3.5.4; requirement and objectives, printed page 120 ↗
Assessment objectives
What must be established
Determine if each applicable objective is satisfied. The labels below follow the cited DoD assessment guide.
- [a]
replay-resistant authentication mechanisms are implemented for network account access to privileged and non-privileged accounts.
MET requires evidence that all applicable objectives are satisfied. Final, approved evidence is needed. A NOT APPLICABLE determination needs a scope-based basis and is equivalent to MET for scoring. Enduring exceptions and temporary deficiencies have specific conditions under 32 CFR 170.24; they are not a general permission to defer implementation.
GAVII Cybersecurity assessment approach
Connect the objective to the evidence
Evaluate the actual network authentication mechanism and protocol configuration. Do not equate an encrypted connection or a password-complexity policy with replay resistance.
Assessment focus: objectives [a]. Use the methods together; a single example does not establish every objective.
Examine
Inspect protocol documentation, authentication settings, and the configuration of applicable network access paths.
Interview
What prevents a captured authentication exchange from being reused, and which legacy protocols remain enabled?
Demonstrate or test
Demonstrate the configured mechanism and validate its replay-resistance properties through documentation and an approved safe test where appropriate.
Evidence gaps to look for
- A secure protocol is available but a weaker fallback is accepted.
- The evidence addresses password strength rather than replay.
GAVII Cybersecurity’s examples illustrate ways to examine, interview, and test. They are not a mandatory artifact list or a guarantee of an assessment result. Combine methods and address every applicable objective in the actual scope.
Assessment constraints
Scoring and POA&M eligibility
Score: 1
If this requirement is NOT MET, deduct 1 point from the Level 2 maximum of 110. The deduction applies to the requirement, not separately to each objective.
Scoring rule ↗POA&M: Eligible
Potentially eligible only if all Conditional Level 2 criteria are satisfied, including a score of at least 88 out of 110 and timely closeout. Eligibility is not a finding that this requirement is MET.
POA&M rule ↗Conditional Level 2 requires a score of at least 88 out of 110 and satisfaction of every eligibility condition. A 1-point requirement is not automatically eligible. The permitted POA&M must be closed through the appropriate closeout assessment within 180 days of the Conditional CMMC Status Date. An operational remediation plan does not confer Conditional Status.
Assessment planning
Location and observation
Not specifically listed in CAP P.11
This requirement is not specifically listed in CAP P.11. That does not establish that remote assessment is sufficient: the Lead CCA and C3PAO determine an adequate approach for the actual scope and evidence.
CAP §P.11, pages 10–11 ↗Check the source
References and related requirements
- DoD CMMC Assessment Guide, Level 2 ↗IA.L2-3.5.4; requirement and objectives, printed page 120. 2.13, September 2024.
- 32 CFR 170.24: Assessment findings and scoring ↗170.24(b) and (c)(2). Current electronic Code of Federal Regulations.
- 32 CFR 170.21: POA&M eligibility and closeout ↗170.21(a)(2) and (b). Current electronic Code of Federal Regulations.
- NIST SP 800-171 Rev. 2 ↗Requirement 3.5.4. February 2020, updated January 2021.
- NIST SP 800-171A ↗Assessment procedure 3.5.4. June 2018.
- Cyber AB CMMC Assessment Process (CAP) ↗P.11, printed pages 10-11; Level 2 certification assessment-location planning. 2.0, December 2024.
Program timing and contract applicability can change independently of these requirements. Check current DoD program notices and your solicitation or contract before making a compliance decision. Open the official DoD resource hub.