CM-5(3): Signed Components

CM-5(3): Signed Components requires you to ensure software, firmware, and other system components are digitally signed and that your environment verifies those signatures before installation, update, or execution. To operationalize it, define which components must be signed, enforce signature verification in build/deploy pipelines and endpoints, control signing keys, and retain evidence that verification is consistently enforced. ¹

Key takeaways:

• Enforce “only signed code runs/installs” for in-scope components, not just a policy statement. ¹
• Treat signing keys and trust stores as high-risk assets with strict ownership, access control, and monitoring.
• Evidence must show prevention (technical controls), not only detection (logs) or intent (procedures).

The cm-5(3): signed components requirement is a configuration and change-control guardrail: your systems should not accept unknown or tampered components. In practice, assessors look for two outcomes: (1) components are signed by an approved signer, and (2) systems verify signatures as a gate before components are installed, updated, or allowed to run. ¹

This control touches multiple teams because “components” span more than application code. Think OS packages, container images, agents, scripts, firmware, infrastructure-as-code modules, CI/CD dependencies, and golden images. If you handle federal data or operate a federal information system, you should assume CM-5(3) will be assessed as part of your baseline expectations under NIST SP 800-53 Rev. 5. ²

Your fastest path to readiness is to pick a clear scope, implement enforcement at the points where change enters the environment (source control, build, artifact repository, deployment, endpoint execution), and document how signature trust is managed. If you use Daydream to manage control ownership and evidence schedules, you can keep CM-5(3) from becoming a scramble right before an assessment.

Regulatory text

Requirement (as provided): “NIST SP 800-53 control CM-5.3.” ¹

Operator interpretation of what this means: CM-5(3): Signed Components expects you to put a trustworthy mechanism in place so that only authenticated, approved components enter or execute within your environment. Operationally, that means you:

• Define which components must be signed (and by whom).
• Distribute and protect the trust anchors (public keys/certificates, trust stores).
• Enforce signature verification in the technical path where changes occur (build, publish, deploy, run).
• Maintain evidence that the controls are implemented and operating as designed. ¹

Plain-English interpretation (what “signed components” really means)

A “signed component” is a piece of software/firmware/configuration packaged with a cryptographic signature that lets a verifier confirm:

1. integrity (it was not altered), and
2. provenance (it came from an approved signer).

CM-5(3) becomes real only when verification is mandatory. If teams can bypass verification “temporarily,” the control usually fails in practice because exceptions become the default.

Who it applies to

Entity scope

• Federal information systems implementing NIST SP 800-53 controls. ²
• Contractor systems handling federal data where NIST SP 800-53 is a contractual or program requirement. ¹

Operational scope (what environments/components are typically in scope)

Define “in scope” using your system boundary. Common in-scope component categories:

• Endpoint executables, scripts, installers, and agent updates
• Server application releases and libraries
• Container images and orchestrator-delivered artifacts
• OS and platform packages from internal mirrors
• Firmware updates for managed devices (where you control the update path)

Documenting exclusions is allowed, but you need a risk-based rationale and compensating controls where feasible.

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

Step 1: Set your signed-component policy as an enforceable standard

Create a short engineering-facing standard that states:

• Which component types must be signed (code, packages, images, firmware).
• Approved signing authorities (internal signing service, approved third-party publishers).
• Where signature verification is enforced (CI build, artifact registry, deployment gate, endpoint policy).
• When exceptions are allowed and who approves them.

Keep it implementer-readable. Assessors will compare this to actual pipeline and endpoint behavior.

Step 2: Build a component inventory and classify by “must be signed”

You can’t enforce signing if you can’t name what must be signed.

• Pull from CMDB, artifact repositories, endpoint management, container registries, and IaC repos.
• Tag each component class with: owner, deployment path, signing method, verification point.

Practical tip: start with the deployment paths that can introduce the most change (CI/CD releases, image pipelines, endpoint software distribution). Expand coverage from there.

Step 3: Establish signing authorities and key management

Decide how signing happens:

• Internal signing (your org signs what it builds).
• Upstream signing (you verify signatures from OS/app publishers).
• Hybrid (verify upstream, then re-sign internally after inspection/repackaging).

Minimum operational requirements:

• Assign an owner for the signing service and trust store.
• Limit who can sign releases (role-based approvals).
• Protect signing keys with strong access controls and change logging.
• Rotate and revoke signing credentials when compromise is suspected.

Auditors commonly focus here because weak signing-key governance collapses the entire control.

Step 4: Enforce signature verification in the CI/CD pipeline

You want “fail closed” controls:

• Build stage: sign the artifact at release time, not ad hoc on a developer workstation.
• Publish stage: artifact repository only accepts signed artifacts (or requires attestations tied to signatures).
• Deploy stage: deployment tooling verifies signature before promoting to environments.
• Dependency stage: verify third-party packages/images before they enter your internal repo.

Evidence priority: screenshots/config exports of pipeline gates, policy-as-code rules, and example failed deployments due to invalid signatures.

Step 5: Enforce signature verification on endpoints and servers

Even good pipelines can be bypassed via manual installs or emergency changes. Put runtime/installation controls in place where possible:

• Application allowlisting or execution control that trusts signed binaries only.
• OS-level controls that require signed drivers/modules.
• Endpoint management that blocks unsigned installers or scripts.

If you cannot enforce “signed only” everywhere, document:

• Where enforcement exists,
• Where it does not,
• What compensating controls apply (for example, restricted admin rights and monitored execution paths).

Step 6: Handle third-party software and updates explicitly

Most environments rely heavily on third party components. Your standard should state:

• How you verify publisher signatures.
• How you manage trust stores/cert pinning (where applicable).
• What you do when a publisher does not sign (risk acceptance, alternative source, sandboxing, or internal wrapping/re-signing).

Avoid vague language like “verify where possible.” Name the enforcement mechanism.

Step 7: Put exception management on rails

Create a lightweight exception process:

• Request form: component, system, reason, duration, compensating controls.
• Approval: security and system owner sign-off.
• Expiration and review: exceptions must end or be renewed with evidence.

This is one place Daydream fits naturally: assign the control owner, map the procedure, and schedule recurring exception reviews and evidence collection so exceptions do not sprawl.

Required evidence and artifacts to retain

Maintain artifacts that prove both design and operation:

• Signed component standard (policy/engineering standard) and scope statement.
• Component inventory excerpt showing which classes require signing and owners.
• Signing key management records: access list, change approvals, rotation/revocation events, HSM/KMS configuration exports if applicable.
• CI/CD configuration evidence: pipeline definition showing signing step and verification gates; artifact repository settings requiring signatures; sample release record.
• Endpoint/server enforcement evidence: configuration profiles, allowlisting policies, OS security settings, screenshots/exports.
• Exception register: approved exceptions, compensating controls, and closure evidence.
• Operational proof: logs or reports showing verification failures are blocked and investigated, plus at least one ticket showing follow-through.

Common exam/audit questions and hangups

Assessors usually probe:

• “Show me where signature verification is enforced (not just performed).”
• “Which components are in scope, and how do you know you covered them?”
• “Who can sign a production release, and how is that access controlled?”
• “How do you verify third party components and updates?”
• “What happens if verification fails? Show an example.”

Hangup pattern: teams can demonstrate signing, but not blocking. Another frequent issue is unclear system boundary, leading to debates about whether endpoints, build agents, or network appliances are included.

Frequent implementation mistakes (and how to avoid them)

1. Signing happens on developer laptops.
   Fix: require signing in controlled CI release jobs with restricted permissions.

2. Verification exists, but is optional.
   Fix: make verification a hard gate in artifact repos, deployment workflows, or endpoint controls.

3. Trust store sprawl.
   Fix: define authoritative trust anchors, manage changes via change control, and monitor for drift.

4. No story for third party software.
   Fix: document publisher verification steps and require signed sources or compensating controls.

5. Evidence is “policy only.”
   Fix: keep configuration exports and a small set of “show-me” examples (failed verification event, blocked deployment, exception closure).

Risk implications (why operators care)

Unsigned or unverified components create a straightforward path for supply chain compromise, unauthorized changes, and persistence mechanisms. CM-5(3) reduces the chance that malicious or altered artifacts enter production through normal change paths. The risk is highest where many teams publish artifacts, where third party dependencies are frequent, or where admins can manually install software outside the pipeline.

A practical execution plan (30/60/90-day)

First 30 days: Define scope and enforce one critical path

• Name the control owner and backup owner; document responsibilities in your GRC system.
• Define “must be signed” component categories for your system boundary.
• Pick one high-value deployment path (for example, production application releases or base images) and implement signing + verification gates end-to-end.
• Stand up an exception register and approval workflow.
• Start an evidence binder: policy, pipeline config exports, sample release.

By 60 days: Expand enforcement and mature key governance

• Bring additional component classes under signing (containers, scripts, OS packages mirrored internally).
• Tighten signing-key controls: restricted roles, approvals, logging, rotation procedure, revocation runbook.
• Add endpoint/server enforcement for at least your managed fleet where feasible.
• Run a tabletop: “signing key compromised” and “verification failures spike.”

By 90 days: Operationalize and make it auditable

• Cover remaining in-scope systems, or document exclusions with compensating controls.
• Implement recurring checks: trust store drift detection, unsigned artifact discovery, exception aging.
• Produce an assessment-ready package in Daydream: control narrative, implementation procedure, and recurring evidence artifacts mapped to CM-5(3). ¹

Frequently Asked Questions

What counts as a “component” for CM-5(3)?

Treat any deployable or executable artifact within your system boundary as a component, including packages, images, scripts, and firmware updates. Define your list explicitly so assessors can see what is covered and what is excluded.

Do we have to sign third party software ourselves?

Not always. You can verify publisher signatures when the third party provides them, but you still need an enforcement point that blocks unverified artifacts.

What’s the minimum evidence an auditor will accept?

A signed-component standard, proof of enforced verification (pipeline or endpoint configs), and records showing who can sign and how keys are protected. Add an exception register and at least one operational example (blocked install/deploy) to avoid “paper control” findings.

How do we handle legacy systems that can’t verify signatures?

Document the limitation, restrict who can install or change components, and put monitoring around change paths. Track it as a risk and use an exception with an owner and a plan, rather than leaving it informal.

Is code signing the same as artifact signing for containers and packages?

They’re related but not identical in tooling and enforcement points. Your requirement implementation should cover the artifact types you actually ship and deploy, not only application binaries.

Where does Daydream fit for this control?

Daydream is useful once you have technical enforcement underway: assign CM-5(3) ownership, document the procedure, schedule recurring evidence pulls (pipeline configs, trust store changes, exception reviews), and keep an assessment-ready record set.

Footnotes

1. NIST SP 800-53 Rev. 5 OSCAL JSON

2. NIST SP 800-53 Rev. 5