CMMC 3.5.1 (Identification): Evidence Examples & What Assessors Actually Check
Control: NIST SP 800-171 Rev. 2 §3.5.1 · CMMC Practice: IA.L2-3.5.1 · Updated June 2026
Plain-English answer
3.5.1 requires you to identify three things: system users (unique identifier per person), processes acting on behalf of users (service/automated accounts), and devices that access the system. It's the foundation that authentication (3.5.2) and accountability (audit logging) build on — you can't prove or trace an identity you never assigned.
Who this applies to
Every organization seeking CMMC Level 2 for a CUI environment.
Why it matters
Unique identification is what makes individual accountability possible — without it, logs can't pin an action to a person, and least privilege can't be enforced. It carries a weighted SPRS deduction if unmet (verify the exact value against the DoD Assessment Methodology).
Control lineage
- CMMC Practice: IA.L2-3.5.1
- NIST 800-171 Rev. 2: §3.5.1 — identify system users, processes acting on behalf of users, and devices.
- NIST 800-171A objectives: [a] system users are identified; [b] processes acting on behalf of users are identified; [c] devices accessing the system are identified.
What the assessor will EXAMINE
- The user/identity directory (e.g., Entra ID, Google Workspace, Active Directory) showing unique per-user accounts.
- An inventory of service/automated accounts (processes acting on behalf of users) and their owners.
- A device inventory and the mechanism by which devices are identified (asset tags, certificates, device IDs, MDM).
- Account/identity management policy and the SSP narrative for 3.5.1.
What the assessor will INTERVIEW & TEST
- Interview: "How is each user, service account, and device uniquely identified?" — name the directory, the service-account register, and the device-identification method.
- Test: Sample the directory for shared/generic accounts that break unique identification.
- Test: Reconcile the device inventory against what's actually connecting for unidentified devices.
Evidence examples (produce these)
- Directory export showing unique user identifiers (no shared logins).
- Service-/automated-account inventory with owners and purpose.
- Device inventory plus the identification method (certificates, MDM device IDs, 802.1X).
- Account-management policy covering naming, uniqueness, and service accounts.
- SSP section 3.5.1 referencing the above.
Common failure patterns
- Shared/generic accounts (a team "admin" login) — breaks objective [a] and individual accountability.
- Service accounts undocumented, so processes acting on behalf of users aren't identified — objective [b] fails.
- No device identification — anything can connect — objective [c] fails.
- Identifiers reused or recycled in a way that confuses traceability.
SPRS impact & POA&M
SPRS: 3.5.1 carries a weighted deduction (verify the exact value). POA&M: confirm 3.5.1's POA&M eligibility against current CMMC rules before assuming it can be deferred.
Assessor-ready summary
You're good on 3.5.1 when every user has a unique identifier, service/automated accounts are inventoried with owners, devices are identified before they connect, and the SSP matches your directory and inventories.
Sure there are no shared logins hiding in your directory? Get an identity & device evidence map →
Related: 3.5.2 Authentication · 3.5.3 MFA · All control pages
Athena prepares organizations for CMMC Level 2; certification rests with C3PAOs/DIBCAC. Verify all control facts against NIST SP 800-171 Rev. 2, NIST SP 800-171A, and current CMMC rules.