NIST 800-171 3.14.5 (SI.L2-3.14.5): Malware Scanning

Perform periodic scans of organizational systems and real-time scans of files from external sources as files are downloaded, opened, or executed.

NIST SP 800-171 Rev. 2, requirement 3.14.5

CMMC Level 2 practice SI.L2-3.14.5Published 2026-11-11

What 3.14.5 means in practice

Two kinds of scanning are required: periodic scans of systems on a defined schedule, and real-time scans of files from outside as they are downloaded, opened or run. Endpoint protection usually does both once it is configured to.

SPRS points and the CMMC POA&M

CMMC Level 2 practice: SI.L2-3.14.5
SPRS points: 3 points. When it is not met, the DoD Assessment Methodology subtracts 3 from the score of 110.
CMMC POA&M: Not allowed. It is worth 3 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 3.14.5

NIST SP 800-171A gives 3 determination statements for 3.14.5, each found satisfied or other than satisfied. Determine if:

3.14.5[a] the frequency for malicious code scans is defined.
3.14.5[b] malicious code scans are performed with the defined frequency.
3.14.5[c] real-time malicious code scans of files from external sources as files are downloaded, opened, or executed are performed.

NIST SP 800-171A (June 2018), assessment objectives for 3.14.5

Evidence that shows 3.14.5 is met

The defined scan frequency.
Endpoint protection settings for scheduled and real-time scanning.
Scan history reports.

How PolicyCortex gathers the evidence

PolicyCortex reads this evidence with the collectors below, read only, and grades 3.14.5 from it. Each line says what the product checks.

Microsoft Defender for Cloud: Secure score and security contacts. Checks that Microsoft Defender protection is on for every endpoint and that real-time scanning is enabled.

Related pages

Calculator: SPRS score calculator: mark 3.14.5 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 7 System and Information Integrity requirements (3.14).
Previous: 3.14.4: Malware Updates
Next: 3.14.6: Attack Monitoring
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.