03.08.09: System Backup – Cryptographic Protection

To meet the 03.08.09: system backup – cryptographic protection requirement, you must ensure backups that contain CUI are protected with strong cryptography wherever they are stored or moved, and you can prove it with configuration and operational evidence. Operationalize it by scoping which backups contain CUI, enforcing encryption with controlled keys, and retaining repeatable evidence of coverage and key management. ¹

Key takeaways:

• Treat backups as production copies of CUI; encrypt them in storage and during transfer. ¹
• Key management is part of the control; auditors will test who can access keys and restore data. ¹
• Evidence beats intent: configs, KMS settings, job logs, restore tests, and exception handling must be retained. ¹

Backups often become the easiest path to exfiltrate Controlled Unclassified Information (CUI): they’re copied broadly, stored cheaply, and restored under pressure. Requirement 03.08.09: System Backup – Cryptographic Protection exists to remove that path by forcing you to apply cryptographic protection to backup data and to operationalize the protection so it stays effective as environments change. ¹

For a Compliance Officer, CCO, or GRC lead, the fastest way to make this real is to treat it as a packaging and key-control problem, not a policy-writing exercise. You need a clear scope of which backup sets contain CUI, a standard encryption approach for each backup platform (endpoint, VM, database, SaaS, file, and cloud snapshots), and a key management model that prevents a single compromised admin account or third party operator from decrypting everything. ¹

This page translates the requirement into concrete steps, exam-ready evidence, and a plan you can run with your IT and security teams. It also calls out the common failure modes assessors find: “encrypted disks” without encrypted backups, encryption turned on but keys shared too widely, and a lack of proof that encryption stayed enabled over time. ¹

Regulatory text

Regulatory excerpt (framework requirement): “NIST SP 800-171 Rev. 3 requirement 03.08.09 (System Backup – Cryptographic Protection).” ¹

Operator meaning: Implement cryptographic protection for system backups that store or transmit CUI so that loss, theft, misdelivery, unauthorized access, or compromise of backup media does not expose CUI in readable form. You also need to run the control, which means encryption remains enforced as backup jobs, repositories, accounts, and storage locations change. ¹

Plain-English interpretation

If a backup contains CUI (full, incremental, snapshot, image-based, database dump, export, archive), it must be encrypted using approved cryptography, and decryption keys must be controlled. Encryption has to follow the backup wherever it goes: to cloud object storage, offsite replication, third party managed backup services, tapes, laptops, or portable drives. ¹

“Cryptographic protection” is not satisfied by access controls alone. Password-protected archives, weak homegrown crypto, or “private bucket” settings are not the same as cryptographic protection. Your assessor will want to see: (a) encryption settings enabled, (b) key custody and access control, and (c) proof that restores work without breaking security. ¹

Who it applies to

Entities

• Federal contractors and subcontractors operating nonfederal systems that handle CUI. ¹

Operational contexts where it triggers

• Any environment where CUI appears in backups: endpoint backups, server/VM backups, database backups, file shares, collaboration platforms, source control, ticketing attachments, and cloud snapshots. ¹
• Any backup handled by a third party (managed service provider, backup SaaS, cloud provider managed backup features). You still own the requirement; the third party can operate controls, but you must validate and document them. ¹

What you actually need to do (step-by-step)

Use this as a field checklist you can assign to infrastructure and security owners.

1) Define the backup scope that contains CUI

1. Identify the “CUI systems” and data stores in scope for NIST SP 800-171. ¹
2. Enumerate backup types that touch those stores: snapshots, exports, replicas, endpoint images, SaaS exports, database dumps, and log archives that may include CUI. ¹
3. Produce a Backup Inventory with: system, data type, backup tool, target location, retention approach, transfer path, and owner. ¹

Practical tip: assessors often find “shadow backups” (developer exports, ad hoc database dumps, laptop backup agents) that bypass central controls. Treat those as first-class scope items and either bring them under the standard or prohibit them. ¹

2) Standardize encryption requirements per backup pattern

For each pattern below, decide how encryption is enforced and how keys are managed.

Pattern A: Backup software writes to a repository (on-prem or cloud)

• Configure encryption for backup data at rest within the backup platform (client-side or server-side encryption supported by the tool). ¹
• Ensure repository storage also enforces encryption at rest (storage-level encryption is acceptable when keys are properly controlled and evidence is available). ¹

Pattern B: Cloud snapshots and managed backups

• Turn on encryption for snapshots/volumes and ensure snapshot copies remain encrypted across accounts/regions if replication is used. ¹
• Prefer customer-managed keys when feasible, because it tightens key custody and gives better audit artifacts. ¹

Pattern C: Portable media (tape, removable drives)

• Require media encryption and documented chain-of-custody for transport and storage. If a third party handles tapes, make encryption and key-handling explicit contractual requirements and test evidence collection. ¹

3) Implement a key management model that an assessor can defend

Your cryptography is only as strong as your key controls.

Minimum operator outcomes to engineer:

• Keys are stored in an approved key management service or HSM-backed system where access is controlled, logged, and reviewable. ¹
• Decryption requires authenticated, authorized roles; “any backup admin can export keys” is a frequent red flag. ¹
• Key rotation and revocation procedures exist, especially for third party access termination and incident response. ¹

4) Encrypt backups in transit (not just at rest)

Document and enforce encrypted transfer channels for:

• Agent-to-repository connections
• Backup replication between sites/accounts
• Administrative access paths used to download backup sets for restore ¹

Evidence expectation: show protocol/TLS enforcement settings in the backup tool and/or storage endpoints, plus logs or configuration exports. ¹

5) Prove restores work without weakening cryptographic protection

Run restore tests that demonstrate:

• Authorized operators can restore encrypted backups using approved workflows.
• Unauthorized users cannot decrypt or restore data outside the workflow.
• Restores don’t force you into insecure “temporary” decrypted staging areas without controls. ¹

6) Operationalize: monitoring, drift control, and exceptions

1. Set a control owner and a backup encryption standard (policy + technical standard + runbook). ¹
2. Implement recurring checks for encryption status across backup jobs and repositories (configuration drift happens after tool upgrades and new workloads). ¹
3. Use an exception process for legacy systems: document compensating controls, a remediation plan, and leadership acceptance. ¹

Daydream note (earned mention): teams often fail this control because evidence is scattered between infrastructure, cloud, backup admins, and third parties. Daydream can track the requirement, map it to your backup platforms and third party attestations, and drive recurring evidence collection so you’re not rebuilding proof during an assessment. ¹

Required evidence and artifacts to retain

Keep artifacts tied to specific backup sets and systems in scope.

Governance artifacts

• Backup & Recovery Policy section requiring cryptographic protection for CUI backups. ¹
• Backup Encryption Standard (what must be encrypted, approved crypto approach, key custody expectations). ¹
• Key management procedure (access approvals, rotation, revocation, break-glass). ¹
• Backup Inventory identifying which systems have CUI in backups and where they are stored. ¹

Technical evidence

• Backup tool configuration exports/screenshots showing encryption enabled for relevant jobs/clients. ¹
• Storage/KMS configuration showing encryption at rest and key control settings (permissions, key policies). ¹
• Evidence of encrypted transport (configuration settings, endpoint policies). ¹
• Restore test records (tickets, run logs, approvals, outcomes). ¹
• Exception register entries for any unencrypted legacy backup flows plus compensating controls and target remediation. ¹

Third party evidence (if outsourced)

• Contract/SOW clauses requiring encrypted backups and defining key ownership and access. ¹
• Third party reports or attestations you already collect, plus your internal validation notes mapping them to this requirement. ¹

Common exam/audit questions and hangups

Assessors tend to probe these points:

1. “Show me which backups contain CUI.” If you can’t trace CUI systems to backup jobs and repositories, you’ll struggle to defend scope. ¹
2. “Is encryption enforced everywhere backups go?” Replication targets and export workflows are common gaps. ¹
3. “Who can decrypt?” Overbroad key permissions, shared admin accounts, and unmanaged break-glass access create findings. ¹
4. “Prove it stayed enabled.” One-time screenshots are weak; show recurring evidence or change control records. ¹
5. “Can you restore?” A control that blocks restores in practice leads to insecure workarounds during incidents. ¹

Frequent implementation mistakes (and how to avoid them)

Mistake	Why it fails	What to do instead
Assuming disk encryption on servers “covers backups”	Backups often live outside the server’s encrypted disk boundary	Enable encryption within the backup workflow and/or repository with controlled keys. 1
Encryption enabled but keys managed by a third party without limits	You may not be able to prove key custody or restrict access	Define key ownership, access, and logging in contracts; collect evidence and validate configurations. 1
Ad hoc exports (ZIPs, SQL dumps) stored in shared drives	Bypasses centralized encryption and retention	Prohibit or standardize exports; route through approved encrypted storage with logged access. 1
No restore testing for encrypted backups	Teams create insecure bypasses during outages	Run controlled restore tests and document secure restore workflows. 1
Evidence scattered across teams	You can’t respond to assessor requests quickly	Centralize evidence mapping to 03.08.09 and automate recurring collection where possible. 1

Enforcement context and risk implications

Public enforcement sources were not provided for this requirement in the materials you supplied, so this page does not cite specific cases. The practical risk is straightforward: unencrypted or weakly protected backups increase the blast radius of credential compromise, lost media, misconfigured storage, and third party operational access. For CUI programs, inability to produce evidence of cryptographic protection is itself a recurring assessment failure mode. ¹

A practical 30/60/90-day execution plan

No public source was provided to justify specific day-count commitments, so treat the sequence below as a planning template you can size to your environment. ¹

First phase: Immediate stabilization

• Name a control owner for 03.08.09 and assign system owners for each CUI backup stream. ¹
• Build the Backup Inventory for CUI systems and identify all repositories and replication targets. ¹
• Block or contain the highest-risk gaps: ad hoc dumps, unmanaged portable media, unknown cloud buckets used for backup exports. ¹

Second phase: Near-term implementation

• Standardize encryption configuration for each backup platform (endpoint, VM, DB, SaaS, cloud snapshots). ¹
• Implement or tighten KMS/HSM-backed key control, including role separation and logged access. ¹
• Update third party contracts/SOWs where they touch CUI backups to reflect encryption and key-handling requirements; add an evidence delivery cadence. ¹

Third phase: Operational maturity

• Establish recurring evidence collection: configuration exports, encryption status checks, and restore test records. ¹
• Add change-management hooks: new systems cannot enter backup scope without encryption and documented key custody. ¹
• Run tabletop exercises for restore under incident conditions to confirm teams don’t break crypto controls in emergencies. ¹

Frequently Asked Questions

Does 03.08.09 require encrypting every backup, or only backups with CUI?

Scope it to backups that contain CUI or can reasonably include CUI based on system function and data flows. If you can’t reliably separate CUI from non-CUI in a backup stream, encrypt the whole stream. ¹

Is “encryption at rest” in cloud storage enough for the 03.08.09: system backup – cryptographic protection requirement?

It can be acceptable if encryption is actually enforced and key access is controlled and auditable. Assessors will still expect proof of key custody and that replication/exports preserve encryption. ¹

What will an assessor ask for as proof that backups are encrypted?

Expect configuration evidence from the backup platform, repository encryption settings, KMS/key policy evidence, and logs showing backup jobs writing encrypted data. One screenshot without context rarely closes the question. ¹

How should we handle third party managed backup services?

Put encryption and key-handling obligations in the contract, then collect evidence that encryption is enabled and keys are restricted. Treat third party access to decrypt as a privileged access risk that needs approvals and logging. ¹

What if legacy systems can’t support encrypted backups?

Document an exception with compensating controls and a remediation plan, and limit exposure by restricting access, isolating storage, and tightening transport/security monitoring. Keep the exception register and leadership approval ready for the assessment. ¹

Do we need to encrypt backups “in transit” too?

If backups are transmitted across networks (agents, replication, uploads, downloads for restore), encrypt the transport channel and retain evidence of enforcement. Auditors often look for gaps in replication and export workflows. ¹

Footnotes

1. NIST SP 800-171 Rev. 3