---
title: "NIST 800-171 3.13.16 (SC.L2-3.13.16): CUI at Rest"
description: "NIST SP 800-171 3.13.16 CUI at Rest: 1 SPRS point, allowed on a CMMC POA&M. The text, what assessors check and the evidence."
url: https://policycortex.com/nist-800-171/system-and-communications-protection/3.13.16
sealed: 2026-11-11
amended: 2026-11-11
register: nist-800-171/system-and-communications-protection/3.13.16
records: 7
digest: sha3:8f350e6acdf6aaf4e75faba5d292b6e7894fc0c6d9a26a343da54260c8fde525
---

# NIST 800-171 3.13.16 (SC.L2-3.13.16): CUI at Rest

NIST 800-171 / System and Communications Protection / 3.13.16

"Protect the confidentiality of CUI at rest." ([NIST SP 800-171 Rev. 2, requirement 3.13.16](https://doi.org/10.6028/NIST.SP.800-171r2))

CMMC Level 2 practice SC.L2-3.13.16.

## What 3.13.16 means in practice

CUI stored on servers, laptops, databases, cloud storage and backups is protected, usually by encryption at rest, so a stolen disk or an exposed storage account does not expose it. Where encryption cannot give adequate protection, NIST's discussion names other means, such as keeping the data in secure offline storage.

## SPRS points and the CMMC POA&M

- **CMMC Level 2 practice**: SC.L2-3.13.16
- **SPRS points**: 1 point. When it is not met, the DoD Assessment Methodology subtracts 1 from the score of 110.
- **CMMC POA&M**: Allowed. It is worth 1 point, and 32 CFR 170.21(a)(2)(ii) admits requirements worth 1 point. Conditional status also needs a score of at least 88, and the item must be closed within 180 days.

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 3.13.16

NIST SP 800-171A gives one determination statement for 3.13.16.

- Determine if the confidentiality of CUI at rest is protected.

[NIST SP 800-171A (June 2018), assessment objectives for 3.13.16](https://doi.org/10.6028/NIST.SP.800-171A)

## Evidence that shows 3.13.16 is met

- Disk and storage encryption settings for servers, endpoints and cloud storage.
- Database encryption settings.
- The list of places where CUI is stored and how each is protected.

## How PolicyCortex gathers the evidence

PolicyCortex reads this evidence with the collectors below, read only, and grades 3.13.16 from it. Each line says what the product checks.

- **Azure Storage: Storage accounts; Azure: Virtual machines and disks.** Checks that every Azure Storage account and managed disk is encrypted at rest.
- **AWS: S3 buckets · EC2 and VPC networking · Data stores · CloudTrail and CloudWatch · Load balancers, API Gateway, CloudFront and Lambda.** Checks encryption at rest across AWS: S3 default encryption, EBS volumes, RDS, EFS, DynamoDB, Redshift, ElastiCache, SNS topics, CloudWatch log groups and API Gateway caches.

## Related pages

- **Calculator**: [SPRS score calculator: mark 3.13.16 and the other 109 requirements and see the score.](https://policycortex.com/sprs-score-calculator#family-SC)
- **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 16 System and Communications Protection requirements (3.13).](https://policycortex.com/nist-800-171/system-and-communications-protection)
- **Previous**: [3.13.15: Session Authenticity](https://policycortex.com/nist-800-171/system-and-communications-protection/3.13.15)
- **Next**: [3.14.1: Flaw Remediation](https://policycortex.com/nist-800-171/system-and-information-integrity/3.14.1)
- **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 | a3117b17ae76 | 6fc35b838044 |
| REC 0001 | MEANING | 53ef93e674f5 | a3117b17ae76 |
| REC 0002 | POINTS AND POA&M | 0f95b64be04c | 53ef93e674f5 |
| REC 0003 | ASSESSMENT OBJECTIVES | afe2c9aa7379 | 0f95b64be04c |
| REC 0004 | EVIDENCE | 6af54d6a4de3 | afe2c9aa7379 |
| REC 0005 | COLLECTORS | a5805ad806e0 | 6af54d6a4de3 |
| REC 0006 | RELATED | 8f350e6acdf6 | a5805ad806e0 |

Head sha3:8f350e6acdf6aaf4e75faba5d292b6e7894fc0c6d9a26a343da54260c8fde525. 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.