NIST Special Publication 800-171 Revision 2

Date Published: January 28th, 2021

Withdrawn on May 14, 2024. Superseded by SP 800-171 Rev. 3

Author(s): Ron Ross (NIST), Victoria Pillitteri (NIST), Kelley Dempsey (NIST), Mark Riddle (NARA), Gary Guissanie (IDA)

Note: A Class Deviation is in effect as of May 2, 2024 (DEVIATION 2024O0013). The deviation clause requires contractors, who are subject to 252.204-7012, to comply with National Institute of Standards and Technology (NIST) Special Publication (SP) 800-171 Revision 2, instead of the version of NIST SP 800-171 in effect at the time the solicitation is issued or as authorized by the contracting officer. Click Here

3.5.5 Prevent reuse of identifiers for a defined period.

Control Family: Identification and Authentication

Control Type: Derived

SPRS Value: 1

SPRS Supplemental Guidance: N/A

CMMC Level(s): IA.L2-3.5.5

Top Ten Failed Requirement: No

Referenced in:

DFARS 252.204-7012

Derived From: NIST SP 800-53r4

  • IA-4

NIST Supplemental Guidance:

N/A

Discussion:

Identifiers are provided for users, processes acting on behalf of users, or devices (3.5.1). Preventing reuse of identifiers implies preventing the assignment of previously used individual, group, role, or device identifiers to different individuals, groups, roles, or devices.

Upon assessment, assessors must determine if-

3.5.5[a] a period within which identifiers cannot be reused is defined
3.5.5[b] reuse of identifiers is prevented within the defined period.

Assessors are instructed to-

Examine: [SELECT FROM: Identification and authentication policy; procedures addressing identifier management; procedures addressing account management; system security plan; system design documentation; system configuration settings and associated documentation; list of system accounts; list of identifiers generated from physical access control devices; other relevant documents or records].

Interview: [SELECT FROM: Personnel with identifier management responsibilities; personnel with information security responsibilities; system or network administrators; system developers].

Test: [SELECT FROM: Mechanisms supporting or implementing identifier management].

FURTHER 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.

Potential Assessment Considerations

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

  • Are account identifiers reused [b]?