DISCUSSION [NIST SP 800-171 R2]

Privileged functions include establishing system accounts, performing system integrity checks, conducting patching operations, or administering cryptographic key management activities. Non-privileged 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 (AC.L1-3.1.2).

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.

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 practice, 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.L1-3.1.2, which defines a requirement to limit types of transactions and functions to those that authorized users are permitted to execute.

Example

As a system administrator for your organization, you have put security controls in place that prevent non-privileged users from performing privileged activities [a,b,c]. However, you accidentally gave a standard user 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 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 system settings to capture the execution of all privileged functions in audit logs [d]?

Copyright

Copyright 2020, 2021 Carnegie Mellon University and The Johns Hopkins University Applied Physics Laboratory LLC.

Copyright 2021 Futures, Inc.

This material is based upon work funded and supported by the Department of Defense under Contract No. FA8702-15-D-0002 with Carnegie Mellon University for the operation of the Software Engineering Institute, a federally funded research and development center, and under Contract No. HQ0034-13-D-0003 and Contract No. N00024-13-D-6400 with the Johns Hopkins University Applied Physics Laboratory LLC, a University Affiliated Research Center.

The view, opinions, and/or findings contained in this material are those of the author(s) and should not be construed as an official Government position, policy, or decision, unless designated by other documentation.

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