Security requirement
- a.Allow only authorized system access for users (or processes acting on behalf of users) that is necessary to accomplish assigned organizational tasks.
- b.Authorize access to [Organization-defined: security functions] and [Organization-defined: security-relevant information].
- c.Review the privileges assigned to roles or classes of users [Organization-defined: frequency] to validate the need for such privileges.
- d.Reassign or remove privileges, as necessary.
Discussion
Organizations employ the principle of least privilege for specific duties and authorized access for users and system processes. Least privilege is applied to the development, implementation, and operation of the system. Organizations consider creating additional processes, roles, and system accounts to achieve least privilege. Security functions include establishing system accounts and assigning privileges, installing software, configuring access authorizations, configuring settings for events to be audited, establishing vulnerability scanning parameters, establishing intrusion detection parameters, and managing audit information. Security-relevant information includes threat and vulnerability information, filtering rules for routers or firewalls, configuration parameters for security services, security architecture, cryptographic key management information, access control lists, and audit information.
Tailoring decisions required
Resolve these values through the governing organization’s approved tailoring and risk-management process before declaring the requirement implemented.
Implementation perspective
Treat Least Privilege as a CUI protection outcome that must be reflected in the system boundary, documented implementation, operational behavior, and assessment evidence. Pay particular attention to approved identities, least privilege, remote access, information flow, and the full account lifecycle.
- Confirm the requirement is in scope for the CUI system components, services, users, and external connections being assessed.
- Resolve every organization-defined parameter through an approved governance and tailoring process.
- Map each clause of the requirement to an accountable owner, implementation mechanism, and evidence source.
- Verify that inherited and shared implementations are supported by current provider evidence and responsibility boundaries.
- Collect evidence during normal operation and review changes, exceptions, and deficiencies on a risk-based cadence.
Questions to ask
- Which CUI assets, data flows, users, and services are protected by this requirement?
- Which portions are implemented locally, inherited, shared, or not applicable, and what evidence supports that determination?
- Do the system security plan, deployed configuration, operating process, and assessment evidence tell the same story?
- What change, incident, or threshold should trigger reassessment?
Evidence and validation
- access authorization and approval records
- account inventories and entitlement exports
- access review results
- authentication and authorization logs
Common failure patterns
- CUI access that exceeds mission need
- shared or orphaned accounts
- remote access paths outside the approved boundary
- access reviews that cannot be reconciled to deployed permissions
Assessment objectives and methods
Assessment objectives (5)
- a.
system access for users (or processes acting on behalf of users) is authorized only when necessary to accomplish assigned organizational tasks.
- b.
access to [Organization-defined: security functions] is authorized.
- b.
access to [Organization-defined: security-relevant information] is authorized.
- c.
the privileges assigned to roles or classes of users are reviewed [Organization-defined: frequency] to validate the need for such privileges.
- d.
privileges are reassigned or removed, as necessary.
Examine
- access control policy and procedures
- procedures for least privilege
- list of assigned access authorizations (i.e., privileges)
- system configuration settings
- system audit records
- list of security functions (implemented in hardware, software, and firmware)
- security-relevant information for which access must be explicitly authorized
- list of system-generated roles or classes of users and assigned privileges
- validation reviews of privileges assigned to roles or classes of users
- records of privilege removals or reassignments for roles or classes of users
- system security plan
- system design documentation
- other relevant documents or records
Interview
- personnel with responsibilities for defining least privileges
- personnel with information security responsibilities
- system administrators
Test
- mechanisms for implementing least privilege functions
- mechanisms for implementing reviews of user privileges
Source NIST SP 800-53 controls
These controls are referenced by the official SP 800-171 Rev. 3 OSCAL record. Open the corresponding control pages for complete control text, enhancements, D3FEND mappings, and related learning.
Authoritative sources
- NIST SP 800-171 Revision 3 official publication ↗
- NIST SP 800-171A Revision 3 official publication ↗
- NIST OSCAL Content release used for this import ↗
Bare Metal Cyber is an independent educational publisher and is not affiliated with or endorsed by NIST. The official publications, the responsible federal agency, and the governing contract or agreement determine applicability, tailoring, assessment depth, and required implementation.