CM.L2-3.4.7 · Level 2

Restrict, disable, or prevent the use of nonessential programs, functions, ports, protocols, and…

NIST SP 800-171 Rev 2 · §3.4.7

Restrict, disable, or prevent the use of nonessential programs, functions, ports, protocols, and services.

Assessment objectives

From NIST SP 800-171A · 15 objectives must be met to satisfy this control

3.4.7[a] essential programs are defined.

Examine

[SELECT FROM: Configuration management policy; procedures addressing least functionality in the system; configuration management plan; security plan; system design documentation; system configuration settings and associated documentation; specifications for preventing software program execution; security configuration checklists; documented reviews of programs, functions, ports, protocols, and/or services; change control records; system audit logs and records; other relevant documents or records].

Interview

[SELECT FROM: Personnel with responsibilities for reviewing programs, functions, ports, protocols, and services on the system; personnel with information security responsibilities; system or network administrators; system developers].

Test

[SELECT FROM: Organizational processes for reviewing and disabling nonessential programs, functions, ports, protocols, or services; mechanisms implementing review and handling of nonessential programs, functions, ports, protocols, or services; organizational processes preventing program execution on the system; organizational processes for software program usage and restrictions; mechanisms supporting or implementing software program usage and restrictions; mechanisms preventing program execution on the system].

3.4.7[b] the use of nonessential programs is defined.

Examine

Interview

Test

3.4.7[c] the use of nonessential programs is restricted, disabled, or prevented as defined.

Examine

Interview

Test

3.4.7[d] essential functions are defined.

Examine

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Test

3.4.7[e] the use of nonessential functions is defined.

Examine

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3.4.7[f] the use of nonessential functions is restricted, disabled, or prevented as defined.

Examine

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Test

3.4.7[g] essential ports are defined.

Examine

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Test

3.4.7[h] the use of nonessential ports is defined.

Examine

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3.4.7[i] the use of nonessential ports is restricted, disabled, or prevented as defined.

Examine

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Test

3.4.7[j] essential protocols are defined.

Examine

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3.4.7[k] the use of nonessential protocols is defined.

Examine

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3.4.7[l] the use of nonessential protocols is restricted, disabled, or prevented as defined.

Examine

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3.4.7[m] essential services are defined.

Examine

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3.4.7[n] the use of nonessential services is defined.

Examine

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3.4.7[o] the use of nonessential services is restricted, disabled, or prevented as defined.

Examine

Interview

Test

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.