---
title: "NIST 800-171 3.4.8 (CM.L2-3.4.8): Application Execution"
description: "NIST SP 800-171 3.4.8 Application Execution: 5 SPRS points, not allowed on a CMMC POA&M. The text, what assessors check and the evidence."
url: https://policycortex.com/nist-800-171/configuration-management/3.4.8
sealed: 2026-11-11
amended: 2026-11-11
register: nist-800-171/configuration-management/3.4.8
records: 7
digest: sha3:a30962af9eb950c8151c878ec66bf7cb0c833e903e48b66fa1ad79d6cfb6bdde
---

# NIST 800-171 3.4.8 (CM.L2-3.4.8): Application Execution

NIST 800-171 / Configuration Management / 3.4.8

"Apply deny-by-exception (blacklisting) policy to prevent the use of unauthorized software or deny-all, permit-by-exception (whitelisting) policy to allow the execution of authorized software." ([NIST SP 800-171 Rev. 2, requirement 3.4.8](https://doi.org/10.6028/NIST.SP.800-171r2))

CMMC Level 2 practice CM.L2-3.4.8.

## What 3.4.8 means in practice

Choose an approach and apply it: either block known unauthorized software (deny by exception) or let only approved software run (deny all, permit by exception). NIST's discussion of the requirement calls the second the stronger of the two. Either way the list of allowed or blocked software is written down and enforced by a tool, not by policy alone.

## SPRS points and the CMMC POA&M

- **CMMC Level 2 practice**: CM.L2-3.4.8
- **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](https://www.acq.osd.mil/asda/dpc/cp/cyber/docs/safeguarding/NIST-SP-800-171-Assessment-Methodology-Version-1.2.1-6.24.2020.pdf); [32 CFR 170.21, Plan of Action and Milestones requirements](https://www.ecfr.gov/current/title-32/section-170.21).

## What an assessor checks for 3.4.8

NIST SP 800-171A gives 3 determination statements for 3.4.8, each found satisfied or other than satisfied. Determine if:

- 3.4.8[a] a policy specifying whether whitelisting or blacklisting is to be implemented is specified.
- 3.4.8[b] the software allowed to execute under whitelisting or denied use under blacklisting is specified.
- 3.4.8[c] whitelisting to allow the execution of authorized software or blacklisting to prevent the use of unauthorized software is implemented as specified.

[NIST SP 800-171A (June 2018), assessment objectives for 3.4.8](https://doi.org/10.6028/NIST.SP.800-171A)

## Evidence that shows 3.4.8 is met

- The policy stating which approach is used.
- The list of allowed or blocked software.
- Configuration of the enforcement tool, such as Windows Defender Application Control, AppLocker or an endpoint protection allowlist.
- Logs of blocked execution attempts.

## How PolicyCortex gathers the evidence

No PolicyCortex collector reads the evidence for 3.4.8. Your team provides the evidence listed above.

## Related pages

- **Calculator**: [SPRS score calculator: mark 3.4.8 and the other 109 requirements and see the score.](https://policycortex.com/sprs-score-calculator#family-CM)
- **Sample package**: [Sample package: an SSP, a POA&M and an evidence chain the product generated from demonstration data.](https://policycortex.com/sample-package)
- **Family**: [All 9 Configuration Management requirements (3.4).](https://policycortex.com/nist-800-171/configuration-management)
- **Previous**: [3.4.7: Nonessential Services](https://policycortex.com/nist-800-171/configuration-management/3.4.7)
- **Next**: [3.4.9: User-Installed Software](https://policycortex.com/nist-800-171/configuration-management/3.4.9)
- **All requirements**: [All 110 NIST SP 800-171 requirements, by family.](https://policycortex.com/nist-800-171)

Meet the requirement once. Keep the evidence current. [Request Access](https://app.policycortex.com/auth?mode=request-access) · [Book a call](https://policycortex.com/book)

## Register colophon

| Seq | Label | SHA3-256 | Prev |
|---|---|---|---|
| REC 0000 | REQUIREMENT | 3b2c9a84fa81 | 2591e0205eb0 |
| REC 0001 | MEANING | 69ba940fde1d | 3b2c9a84fa81 |
| REC 0002 | POINTS AND POA&M | 817ccfeeee1f | 69ba940fde1d |
| REC 0003 | ASSESSMENT OBJECTIVES | c22abd254bc0 | 817ccfeeee1f |
| REC 0004 | EVIDENCE | 9272936b0fe3 | c22abd254bc0 |
| REC 0005 | COLLECTORS | 8e8d87ccb5f7 | 9272936b0fe3 |
| REC 0006 | RELATED | a30962af9eb9 | 8e8d87ccb5f7 |

Head sha3:a30962af9eb950c8151c878ec66bf7cb0c833e903e48b66fa1ad79d6cfb6bdde. Each digest is SHA3-256 over the previous digest, the register key, the record label, and the record copy; a second party can recompute it from this document.