NIST 800-171 3.4.6 (CM.L2-3.4.6): Least Functionality

Employ the principle of least functionality by configuring organizational systems to provide only essential capabilities.

NIST SP 800-171 Rev. 2, requirement 3.4.6

CMMC Level 2 practice CM.L2-3.4.6Published 2026-11-11

What 3.4.6 means in practice

Systems provide only the capabilities the mission needs. Define the essential capabilities of each system and remove or disable the rest, so there are fewer features, services and components to attack.

SPRS points and the CMMC POA&M

CMMC Level 2 practice: CM.L2-3.4.6
SPRS points: 5 points. When it is not met, the DoD Assessment Methodology subtracts 5 from the score of 110.
CMMC POA&M: Not allowed. It is worth 5 points, and 32 CFR 170.21(a)(2)(ii) admits only requirements worth 1 point, with one exception: 3.13.11 when encryption is used but not FIPS validated.

Sources: NIST SP 800-171 DoD Assessment Methodology, version 1.2.1 (June 24, 2020), Annex A; 32 CFR 170.21, Plan of Action and Milestones requirements.

What an assessor checks for 3.4.6

NIST SP 800-171A gives 2 determination statements for 3.4.6, each found satisfied or other than satisfied. Determine if:

3.4.6[a] essential system capabilities are defined based on the principle of least functionality.
3.4.6[b] the system is configured to provide only the defined essential capabilities.

NIST SP 800-171A (June 2018), assessment objectives for 3.4.6

Evidence that shows 3.4.6 is met

A list of the essential capabilities of each system type.
Hardened images or configuration records showing unneeded features removed.
Policy settings that block resource types and services that are not needed.

How PolicyCortex gathers the evidence

PolicyCortex reads this evidence with the collectors below, read only, and grades 3.4.6 from it. Each line says what the product checks.

Azure: Network security groups. Checks network security group rules for unnecessary open ports and protocols.
Azure Policy: Assignments. Checks that Azure Policy restricts nonessential resource types and services.

Related pages

Calculator: SPRS score calculator: mark 3.4.6 and the other 109 requirements and see the score.
Sample package: Sample package: an SSP, a POA&M and an evidence chain the product generated from demonstration data.
Family: All 9 Configuration Management requirements (3.4).
Previous: 3.4.5: Change Access Limits
Next: 3.4.7: Nonessential Services
All requirements: All 110 NIST SP 800-171 requirements, by family.

Related records

Guides and articles describe the work. The evidence that work produces is described in three proof pages, the architecture page, and the two pages on authorization.

proof.state: Proof of State. What the environment was, as of a date someone else picks: point-in-time records, content hashed and chained.
proof.change: Proof of Change. Who or what altered the environment, under what authority, with before and after state hashes.
proof.agency: Proof of Agency. What a machine was permitted to do before it acted, what it did, and what would have stopped it.
architecture: Architecture. How the chain is built and where the evidence is stored in each delivery mode.
authorization: Continuous ATO. How an authorizing official's decision is recorded with its package, and how the authorized system is checked against it every hour.
baseline: NIST SP 800-53. The Low, Moderate and High baselines as evidence, with the SSP, SAR and POA&M generated from one record.