CA-3(7): Transitive Information Exchanges

CA-3(7) requires you to identify “transitive” (downstream) information exchanges: where your system shares data with System A, and System A then passes that data (or derived data) to other systems you don’t directly interface with. To operationalize it, you must map each approved interface to downstream dependencies, assess the resulting exposure, and keep evidence that the mapping stays current. ¹

Key takeaways:

• Treat transitive exchanges as part of your system boundary risk, even if the downstream systems are “someone else’s problem.”
• Your core deliverable is an interface-to-downstream “data path” map tied to CA-3 agreements and reviewed on change.
• Auditors look for completeness (no “unknown downstreams”) and repeatability (a process, not a one-time diagram).

The ca-3(7): transitive information exchanges requirement exists because modern system connections rarely stop at the first hop. You may have a documented interface to a partner platform, a shared service, an identity provider, a logging pipeline, a managed database, or a SaaS tool. That first-hop system often forwards telemetry, content, or identifiers to additional systems for storage, analytics, support, fraud detection, backups, or subcontracted operations.

For a Compliance Officer, CCO, or GRC lead, the practical goal is simple: eliminate “unknown downstream” paths for any information exchange you approved under CA-3, and be able to show an assessor how you know where your data can go. CA-3(7) is not asking you to control every downstream system directly. It is asking you to identify those transitive exchanges so risk decisions, contract clauses, monitoring, and incident response are grounded in reality. ²

This page gives requirement-level implementation guidance you can assign to an owner, run as a repeatable workflow, and defend in an audit with clear artifacts.

Regulatory text

NIST requirement (excerpt): “Identify transitive (downstream) information exchanges with other systems through the systems identified in CA-3a; and” ¹

What the operator must do: For every system-to-system exchange you already identified and approved under CA-3(a), you must also identify the next hops: other systems that receive your information through that intermediary. The expected outcome is a defensible inventory of downstream exchanges, tied to each interface, that you keep current as integrations and third parties change. ¹

Plain-English interpretation (what CA-3(7) means day to day)

A transitive exchange is a “shared-with-our-partner, then shared-again” flow. Common examples:

• You send authentication events to an identity provider; the provider sends logs to a SIEM subcontractor.
• You send customer records to a SaaS; the SaaS sends backups to a separate cloud environment.
• You send payment metadata to a processor; the processor sends risk signals to a fraud analytics service.

Your obligation is to know and document those downstream paths so you can:

• validate the exchange is authorized for the data involved,
• ensure contractual/security requirements extend downstream where needed,
• update your risk assessment and incident response assumptions.

Who it applies to (entity and operational context)

CA-3(7) applies when you operate:

• Federal information systems, or
• Contractor systems handling federal data (for example, systems in scope for federal contracts or authorizations). ²

Operationally, it applies to any environment where your system exchanges information with:

• external systems owned by third parties (SaaS, cloud services, MSPs, data providers),
• internal shared services (enterprise logging, identity, network services),
• interconnected federal or partner systems.

If your organization has APIs, event streams, file transfers, SSO/SAML/OIDC, managed detection, outsourced support tooling, or centralized data platforms, you have transitive exchanges.

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

Use the steps below as an implementation procedure you can assign to a control owner.

1) Establish scope from CA-3(a)

Start with the authoritative list of interfaces and interconnections identified under CA-3(a): integration inventory, interface control documents, interconnection security agreements, API gateway catalog, network diagrams, or CMDB relationships. CA-3(7) is downstream of that list by design. ¹

Output: “CA-3(a) interface register” with unique interface IDs.

2) Define what counts as “information exchange”

Make this explicit so engineering teams don’t narrow the scope to only production APIs. Include:

• telemetry/log forwarding,
• backups and disaster recovery replication,
• support tooling access and ticketing attachments,
• identity assertions and directory sync,
• batch file exchanges and SFTP,
• message queues/event buses.

Output: A written scoping statement embedded into your CA-3(7) procedure.

3) For each interface, map transitive paths (first hop → downstream)

For each CA-3(a) interface, require the system owner (or third-party relationship owner) to document:

• downstream systems that receive your information from the first hop,
• purpose of downstream forwarding (support, analytics, security monitoring, storage),
• categories of information forwarded (content, metadata, identifiers),
• whether downstream recipients are subcontractors, separate business units, or separate platforms.

Practical methods to get reliable answers:

• contract/SOW review for subcontractor and data handling terms,
• vendor/third-party due diligence questionnaires focused on onward transfers,
• architecture review with the integration owner,
• inspection of vendor trust documentation where available (but record what you relied on).

Output: A “Transitive Exchange Map” (table format works best; see template below).

4) Classify data and risk per transitive exchange

For each downstream exchange, record:

• data sensitivity impact if disclosed or altered,
• whether data minimization is applied (only necessary fields),
• whether encryption and strong authentication are expected for that path,
• operational dependency and single points of failure created by the chain.

You do not need a perfect quant model; you need consistent classification that drives required controls and contract terms.

Output: Risk notes and required control flags attached to each transitive exchange entry.

5) Update agreements and obligations to cover downstream recipients

Where transitive exchanges exist, confirm your CA-3 documentation and third-party terms reflect the reality of onward transfers. Typical actions:

• require the first-hop third party to flow down security requirements to subcontractors,
• require notification of new downstream recipients,
• require breach notification and cooperation obligations that include subcontractors,
• restrict cross-border transfers if your program requires it.

Output: Updated contract clauses/SOW addenda, or written acceptance of residual risk with named downstream systems.

6) Implement change triggers so the map stays current

CA-3(7) fails in practice when teams build a diagram once and never refresh it. Add triggers to your operational change points:

• new integration onboarding,
• vendor/third-party renewal,
• new feature sending new fields,
• vendor adds a new subprocessors/downstream system,
• incident or audit finding.

Output: A lightweight workflow (ticket template + approvers) that forces downstream mapping before go-live or renewal.

7) Review, approve, and retain evidence

Have a clear approval step: system owner + security + privacy (as applicable) sign off that transitive exchanges are identified and either authorized or blocked.

Output: Approval record and evidence package stored with the interface register.

Suggested “Transitive Exchange Map” template (minimum viable)

CA-3(a) Interface ID	First-hop system	Data elements shared	Downstream systems (names)	Purpose	Data sensitivity	Contract/flow-down confirmed (Y/N)	Owner	Last reviewed

Required evidence and artifacts to retain

Auditors tend to accept several formats as long as they are complete, current, and traceable. Keep:

• CA-3(a) interface register (the source list for CA-3(7)) ¹
• Transitive Exchange Map for each interface, including “unknown = none” is not acceptable; you need an affirmative basis for “no downstream forwarding”
• Third-party due diligence evidence that addresses onward transfers/subprocessors (questionnaire responses, attestations you received, written confirmations)
• Architecture or data flow diagrams showing first-hop and downstream hops (a table is fine if diagrams are hard)
• Change management records showing CA-3(7) review occurred for new/changed interfaces
• Risk acceptance records where downstream paths are high risk but approved
• Contract artifacts showing flow-down requirements, notification obligations, and restrictions tied to transitive exchanges

Daydream fits naturally here as the system of record to assign a control owner, store the procedure, and generate recurring evidence requests tied to each interface and third party, so CA-3(7) stays audit-ready instead of living in scattered spreadsheets.

Common exam/audit questions and hangups

Expect questions like:

• “Show me how you know where this data goes after it reaches the first external system.”
• “Which of your interconnections involve onward transfer to subcontractors or separate platforms?”
• “How do you detect when a third party adds a new downstream recipient?”
• “How does CA-3(7) tie back to your CA-3(a) inventory?”
• “Who approves transitive exchanges, and what is the decision criteria?”

Hangups that derail audits:

• inconsistent definitions of “system” vs “service” vs “subprocessor,”
• “we rely on the vendor’s SOC report” without mapping actual downstream recipients,
• interface lists that exclude logging/monitoring and support tooling.

Frequent implementation mistakes (and how to avoid them)

1. Only mapping production APIs. Fix: include identity, logs, backups, and support access in your “information exchange” definition.
2. Accepting “we don’t know” from third parties. Fix: require an affirmative statement about onward transfers, plus a notification obligation for changes.
3. No linkage to CA-3(a). Fix: assign interface IDs and make the transitive map a required field for each interface entry.
4. No change triggers. Fix: embed CA-3(7) checks into onboarding and renewal workflows; require updates before go-live.
5. Storing diagrams without decision evidence. Fix: attach approval records and risk acceptance notes to each transitive exchange.

Enforcement context and risk implications

No public enforcement cases were provided in the source material for this specific enhancement, so you should treat CA-3(7) primarily as an assessment-readiness and risk-reduction requirement rather than something tied to a specific published penalty in this dataset. The operational risk is straightforward: unknown downstream transfers expand your attack surface, complicate incident response, and undermine contractual and authorization assumptions. ²

Practical 30/60/90-day execution plan

First 30 days (establish control and inventory)

• Name a CA-3(7) control owner and backups.
• Confirm the authoritative CA-3(a) interface list and reconcile duplicates.
• Publish the CA-3(7) procedure: definition of information exchange, required fields, and approval workflow.
• Pilot transitive mapping for the highest-risk interfaces (federal data, external third parties, broad data scope).

Days 31–60 (complete mapping and close gaps)

• Complete transitive maps for remaining interfaces in scope.
• Identify “unknown downstream” cases and drive targeted third-party follow-up.
• Update contracts/SOWs for renewal candidates to add flow-down and notification terms.
• Add a required CA-3(7) step to integration onboarding and procurement/renewal checklists.

Days 61–90 (operationalize and make it repeatable)

• Run a tabletop: pick one interface and simulate a downstream breach notification path; validate contacts and obligations.
• Implement periodic attestations from key third parties about subprocessors/downstream recipients.
• Build an audit-ready evidence package: interface register, maps, approvals, and sample change tickets.
• In Daydream, schedule recurring evidence tasks and map CA-3(7) to owners, procedures, and artifacts so reviews happen on time.

Frequently Asked Questions

Do we have to get technical network-level proof of every downstream transfer?

No. CA-3(7) requires identification of transitive exchanges; you can satisfy this with contractual documentation, third-party attestations, and architecture/data flow documentation that credibly describes onward transfers. ¹

What if the third party refuses to disclose downstream systems?

Treat that as a risk decision. Escalate for exception approval, document the limitation, and pursue contract language requiring disclosure or at least notification of new downstream recipients, plus flow-down obligations.

Are internal shared services “transitive exchanges”?

They can be. If your system sends data to an internal platform that then routes data to other systems (for example, enterprise logging forwarding to another environment), map those downstream hops the same way.

How detailed does the “data elements shared” field need to be?

Detailed enough to support risk decisions and minimization. List categories and key identifiers (for example, user ID, IP address, audit logs, document content) rather than dumping full schemas unless your process requires it.

How do we keep this current without turning it into a quarterly fire drill?

Put CA-3(7) updates behind change triggers: new integrations, renewed contracts, and material data field changes. Track ownership per interface and require sign-off before releases.

What’s the minimum evidence an auditor will accept?

A traceable interface register tied to CA-3(a), a transitive exchange map for each interface, and proof of review/approval on change are the minimum credible set. Keep supporting third-party responses and contract terms for high-risk exchanges. ¹

Footnotes

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

2. NIST SP 800-53 Rev. 5