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Withdrawn on May 14, 2024. Superseded by SP 800-171 Rev. 3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

3.1.7 Prevent non-privileged users from executing privileged functions and capture the execution of such functions in audit logs.

Control Family: Access Control

Control Type: Derived

SPRS Value: 1

CMMC Level(s): AC.L2-3.1.7

Top Ten Failed Requirement: No

Referenced in:

DFARS 252.204-7012

Derived From: NIST SP 800-53r4

  • AC-6(9)

  • AC-6(10)

Discussion:

Privileged functions include establishing system accounts, performing system integrity checks, conducting patching operations, or administering cryptographic key management activities. Nonprivileged users are individuals that do not possess appropriate authorizations. Circumventing intrusion detection and prevention mechanisms or malicious code protection mechanisms are examples of privileged functions that require protection from non-privileged users. Note that this requirement represents a condition to be achieved by the definition of authorized privileges in 3.1.2.

Misuse of privileged functions, either intentionally or unintentionally by authorized users, or by unauthorized external entities that have compromised system accounts, is a serious and ongoing concern and can have significant adverse impacts on organizations. Logging the use of privileged functions is one way to detect such misuse, and in doing so, help mitigate the risk from insider threats and the advanced persistent threat.

Determining Statements (NIST SP 800-171Ar2)

Upon assessment, assessors must determine if-

3.1.7[a] privileged functions are defined.
3.1.7[b] non-privileged users are defined.
3.1.7[c] non-privileged users are prevented from executing privileged functions.
3.1.7[d] the execution of privileged functions is captured in audit logs.

Assessors are instructed to-

Examine: [SELECT FROM: Access control policy; procedures addressing least privilege; system security plan; system design documentation; list of privileged functions and associated user account assignments; system configuration settings and associated documentation; system audit logs and records; other relevant documents or records].

Interview: [SELECT FROM: Personnel with responsibilities for defining least privileges necessary to accomplish specified tasks; personnel with information security responsibilities; system developers].

Test: [SELECT FROM: Mechanisms implementing least privilege functions for non-privileged users; mechanisms auditing the execution of privileged functions].

FURTHER DISCUSSION

Non-privileged users should receive only those permissions required to perform their basic job functions. Privileged users are granted additional permissions because their jobs require them. Privileged functions typically involve the control, monitoring, or administration of the system and its security measures. When these special privileged functions are performed, the activity must be captured in an audit log, which can be used to identify abuse. Nonprivileged employees must not be granted permission to perform any of the functions of a privileged user. This requirement, AC.L2-3.1.7, manages non-privileged users by logging any attempts to execute privileged functions. AC.L2-3.1.7 leverages AU.L2-3.3.2, which ensures logging and traceability of user actions. AC.L2-3.1.7 also extends AC.L2-3.1.2, which defines a requirement to limit types of transactions and functions to those that authorized users are permitted to execute.

Example

Your organization handles CUI and has put security controls in place that prevent nonprivileged users from performing privileged activities [a,b,c]. However, a standard user was accidentally given elevated system administrator privileges. The organization has implemented an endpoint detection and response solution that provides visibility into the use of privileged activities. The monitoring system logs a security misconfiguration because the use of administrative privileges was performed by a user who was not known to have that ability. This allows you to correct the error [d].

Potential Assessment Considerations

  • Is it possible to identify who enabled privileges at any particular time [d]?

  • Are the privileged system functions documented (e.g., functions that involve the control, monitoring or administration of the system, including security functions and log management) [a]?

  • Do documented procedures describe the configuration of the system to ensure system roles do not grant non-privileged users the ability to execute privileged functions [c]?

  • Do procedures describe the configuration of all privileged functions in audit logs [d]?

Frameworks & Controls