Overview
  1. 03.01: Access Control
  2. 03.02: Awareness and Training
  3. 03.03: Audit and Accountability
  4. 03.04: Configuration Management
  5. 03.05: Identification and Authentication
  6. 03.06: Incident Response
  7. 03.07: Maintenance
  8. 03.08: Media Protection
  9. 03.09: Personnel Security
  10. 03.10: Physical Protection
  11. 03.11: Risk Assessment
  12. 03.12: Security Assessment
  13. 03.13: System and Communications Protection
  14. 03.14: System and Information Integrity

Security Requirements for 03.05.05 Identifier Reuse

Identifiers are provided for users, processes acting on behalf of users, or devices (03.05.01). Preventing reuse of identifiers implies preventing the assignment of previously used individual, group, role, or device identifiers to different individuals, groups, roles, or devices.

Assessment GuidanceExamine 0/10

How an assessor determines this requirement is met. Source: CMMC Assessment Guide – Level 2, Version 2.13 (NIST SP 800-171 Rev. 2).

Discussion

Identifiers uniquely associate a user ID to an individual, group, role, or device. Establish guidelines and implement mechanisms to prevent identifiers from being reused for the period of time established in the policy.

Example As a system administrator, you maintain a central directory/domain that holds the accounts for users, computers, and network devices. As part of your job, you issue unique usernames (e.g., riley@acme.com) for the staff to access resources. When you issue staff computers you also rename the computer to reflect to whom it is assigned (e.g., riley-laptop01). Riley has recently left the organization, so you must manage the former staff member’s account. Incidentally, their replacement is also named Riley. In the directory, you do not assign the previous account to the new user, as policy has defined an identifier reuse period of 24 months [a]. In accordance with policy, you create an account called riley02 [b]. This account is assigned the appropriate permissions for the new user. A new laptop is also provided with the identifier of riley02-laptop01.

Assessment Methods

Examine
The process of reviewing, inspecting, observing, studying, or analyzing assessment objects (e.g., policies, procedures, plans, system designs, mechanisms) to facilitate understanding, achieve clarification, or obtain evidence.Example: An assessor reads the access control policy and inspects system configuration settings to confirm they match.

Not all of the evidence listed is required to meet this requirement — check the items your organization has collected.

Interview
The process of holding discussions with individuals or groups within an organization to facilitate understanding, achieve clarification, or identify the location of evidence.Example: An assessor asks a system administrator to describe how user accounts are approved, reviewed, and disabled.
  • Personnel with authenticator management responsibilities
  • Personnel with information security responsibilities
  • System or network administrators
Test
The process of exercising assessment objects (e.g., activities, mechanisms) under specified conditions to compare actual behavior with expected behavior.Example: An assessor attempts to sign in with a disabled account to confirm that access is denied.
  • Mechanisms supporting or implementing authenticator management capability

Potential Assessment Considerations

  • Are accounts uniquely assigned to employees, contractors, and subcontractors [b]?
  • Are account identifiers reused [b]?

Key References

NIST SP 800-171 Rev. 2 3.5.5

Evidence

  1. 03.05.05.a

    A period within which identifiers cannot be reused is defined

  1. 03.05.05.b

    Reuse of identifiers is prevented within the defined period