3.4.6
CM.L2-3.4.6 · Level 2
Employ the principle of least functionality by configuring organizational systems to provide only…
NIST SP 800-171 Rev 2 · §3.4.6
Employ the principle of least functionality by configuring organizational systems to provide only essential capabilities.
Assessment objectives
From NIST SP 800-171A · 2 objectives must be met to satisfy this control
Examine
[SELECT FROM: Configuration management policy; configuration management plan; procedures addressing least functionality in the system; security plan; system design documentation; system configuration settings and associated documentation; security configuration checklists; other relevant documents or records].
Interview
[SELECT FROM: Personnel with security configuration management responsibilities; personnel with information security responsibilities; system or network administrators].
Test
[SELECT FROM: Organizational processes prohibiting or restricting functions, ports, protocols, or services; mechanisms implementing restrictions or prohibition of functions, ports, protocols, or services].
Examine
[SELECT FROM: Configuration management policy; configuration management plan; procedures addressing least functionality in the system; security plan; system design documentation; system configuration settings and associated documentation; security configuration checklists; other relevant documents or records].
Interview
[SELECT FROM: Personnel with security configuration management responsibilities; personnel with information security responsibilities; system or network administrators].
Test
[SELECT FROM: Organizational processes prohibiting or restricting functions, ports, protocols, or services; mechanisms implementing restrictions or prohibition of functions, ports, protocols, or services].
What we look for in practice
The following are placeholder notes that should be refined based on practice experience.
What assessors look for in practice. Documented evidence that this control is implemented across all CUI-handling systems within scope. Specific artifacts vary, but expect requests for written procedures, system configurations, and operational records demonstrating the control is active.
Common failure patterns. Typical issues include incomplete documentation, inconsistent implementation across systems, and missing periodic review records. Refine this section as your practice accumulates direct assessment experience.
Strong evidence looks like. Formal policy referencing this control, technical configurations demonstrating enforcement, periodic review logs with sign-off, and procedures for handling exceptions.
Scoring and POA&M context. 5-point control under the DoD Assessment Methodology. Highest scoring impact — treat as a foundational requirement. Not POA&M-eligible — must be implemented at assessment time.