• Requirement

    Identify system users, processes acting on behalf of users, and devices.

  • Discussion

    Common device identifiers include media access control (MAC), Internet Protocol (IP) addresses, or device-unique token identifiers. Management of individual identifiers is not applicable to shared system accounts. Typically, individual identifiers are the user names associated with the system accounts assigned to those individuals. Organizations may require unique identification of individuals in group accounts or for detailed accountability of individual activity. In addition, this requirement addresses individual identifiers that are not necessarily associated with system accounts. Organizational devices requiring identification may be defined by type, by device, or by a combination of type/device. NIST SP 800-63-3 provides guidance on digital identities.

More Info

  • Title

    Identification [CUI Data]
  • Domain

    Identification and Authentication
  • CMMC Level

  • Further Discussion

    Make sure to assign individual, unique identifiers (e.g., user names) to all users and processes that access company systems. Authorized devices also should have unique identifiers. Unique identifiers can be as simple as a short set of alphanumeric characters (e.g., SW001 could refer to a network switch, SW002 could refer to a different network switch).

    This requirement, IA.L2-3.5.1, provides a vetted and trusted identity that supports the access control mechanism required by AC.L2-3.1.1.


    You want to make sure that all employees working on a project can access important information about it. Because this is work for the DoD and may contain CUI, you also need to prevent employees who are not working on that project from being able to access the information. You assign each employee is assigned a unique user ID, which they use to log into the system [a].

    Potential Assessment Considerations

    • Are unique identifiers issued to individual users (e.g., usernames) [a]?
    • Are the processes and service accounts that an authorized user initiates identified (e.g., scripts, automatic updates, configuration updates, vulnerability scans) [b]?
    • Are unique device identifiers used for devices that access the system identified [c]?

NIST 800-171A Assessment Guidance

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