CA-3: Information Exchange

CA-3 requires you to formally approve and actively manage every information exchange between your system and any other system (including third parties), using defined, documented mechanisms and conditions ¹. Operationally, that means maintaining an inventory of interfaces, enforcing approved exchange methods, and retaining evidence that exchanges are authorized, controlled, and monitored.

Key takeaways:

• Treat every interface (API, SFTP, shared database, federated identity, SaaS integration) as an “information exchange” that needs explicit approval.
• Build a repeatable intake-to-approval workflow with technical guardrails, not just a policy statement.
• Your audit win condition is evidence: approved exchanges, documented mechanisms, and proof controls operate in production.

The ca-3: information exchange requirement is where “we connect systems” stops being an engineering convenience and becomes a controlled, auditable security decision. If your environment includes APIs, data feeds, identity federation, shared storage, SIEM forwarding, managed services, or contractor access, you already have information exchanges. CA-3 expects you to approve those exchanges and manage them over time, not merely document them once.

For a CCO, compliance officer, or GRC lead, the fastest path to operationalizing CA-3 is to translate it into (1) a complete interface register, (2) an approval workflow tied to risk and data classification, and (3) technical enforcement for how data moves across boundaries. “Manage” is the keyword: you need a lifecycle that covers onboarding, change control, periodic review, and termination of an exchange.

This page gives requirement-level implementation guidance you can assign to control owners and validate with evidence. It prioritizes exam readiness: what auditors ask, what artifacts they expect, and what breaks most often in real environments.

Regulatory text

Requirement (CA-3): “Approve and manage the exchange of information between the system and other systems using [organization-defined parameters]” ¹.

Operator interpretation: You must (a) decide what counts as an information exchange in your environment, (b) require documented approval before the exchange goes live, and (c) keep the exchange under control through monitoring and change management. “Organization-defined parameters” is your job: you define the allowed exchange mechanisms, required security controls, required approvers, and required evidence.

Reference: NIST SP 800-53 Rev. 5 ².

Plain-English interpretation (what CA-3 is asking for)

CA-3 expects a governed interface lifecycle:

• Know what connections exist between your system and other systems.
• Approve each exchange based on data sensitivity, purpose, and risk.
• Constrain how exchanges happen (approved protocols, encryption, authentication, authorization, logging).
• Keep it current as systems and integrations change.

If you cannot answer, “What systems exchange information with this system, how, and who approved it?” you are likely not meeting CA-3.

Who it applies to (entity + operational context)

CA-3 commonly applies to:

• Federal information systems and the programs operating them ².
• Contractor systems handling federal data where NIST SP 800-53 is in scope by contract, system security plan, or assessment boundary ².

Operationally, it applies wherever your “system” boundary touches:

• Third parties: SaaS providers, managed service providers, payment processors, EDI partners, call centers, claims administrators, benefits administrators, consultants.
• Internal systems: HRIS, CRM, ERP, data warehouse, IAM, logging, endpoint management, ticketing.
• Integration patterns: APIs, webhooks, file drops (SFTP), message queues, database links, ETL pipelines, browser-based admin portals, VPN, VDI, federation (SAML/OIDC), SCIM provisioning.

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

Use this workflow to operationalize CA-3 quickly and make it auditable.

1) Define “information exchange” and set approval triggers

Write a short CA-3 standard (1–2 pages) that defines:

• What counts as an exchange (API, batch file, interactive access, identity federation, telemetry forwarding).
• What events require approval: new exchange, material change (new data types, new endpoint, new third party), and renewal/recertification.
• Your “organization-defined parameters”: allowed mechanisms, minimum control set, and required approvers ¹.

Practical tip: include “shadow” exchanges such as analysts manually exporting data to a third party portal. Auditors will still treat that as an exchange.

2) Build an Information Exchange Register (IER) tied to system boundary

Create a living inventory entry for each exchange. Minimum fields:

• Exchange ID/name, system owner, integration owner.
• Counterparty system and owner (internal team or third party).
• Data types/classification and purpose/authorized use.
• Directionality (inbound/outbound/bidirectional).
• Mechanism (API gateway, SFTP, message bus, federation, VPN).
• Security controls: authentication method, authorization model, encryption in transit, key/cert ownership, logging/monitoring.
• Approval status and approvers; dates; review frequency (your defined parameter).
• Change history and termination criteria.

This register is the core CA-3 artifact. If you already have an architecture repository, CMDB, or integration catalog, extend it rather than starting from scratch.

3) Implement an intake and approval workflow (make approvals provable)

Stand up a formal request process (ticket/work item) for every exchange:

• Requester submits: purpose, data types, mechanism, counterparty, and expected volumes.
• Security review checks: data minimization, authn/authz, encryption, logging, and boundary protections.
• Privacy/compliance review confirms: permitted use and sharing constraints (as applicable).
• System owner approval formally authorizes the exchange and accepts residual risk.
• Third-party risk review (when a third party is involved): confirm due diligence, contract terms, and security requirements align.

Make approvals hard to bypass: require the ticket ID in firewall rules, API gateway route creation, IAM trust setup, or SFTP account creation.

4) Standardize allowed exchange mechanisms (“approved methods” list)

Define and publish the small set of exchange patterns you allow by default, for example:

• API via API gateway with centralized auth and logging.
• Managed SFTP with per-counterparty accounts and folder isolation.
• Federated identity via approved IdP with MFA and conditional access.
• Message queue with per-topic authorization and encryption.

Then define “exceptions” and who can approve them. CA-3 becomes far easier to run when engineers have paved roads.

5) Enforce technical controls at the boundary

Evidence needs to show you manage exchanges in operation, not just on paper. Common controls to implement and map to each exchange:

• Network controls: allowlists, segmentation, inbound/outbound restrictions.
• Strong authentication and scoped authorization (service accounts, least privilege).
• Encryption in transit (TLS) and managed certificate lifecycle.
• Logging of access and data transfer events, routed to monitoring.
• DLP or egress controls where sensitive data moves outward.

Your goal is to make the exchange mechanism itself enforce what was approved.

6) Monitor and periodically revalidate exchanges

Management means you keep exchanges current:

• Detect new/unapproved interfaces (cloud security posture tools, firewall rule review, API gateway inventory, IAM trust review).
• Periodically revalidate high-risk exchanges: confirm purpose still valid, data scope unchanged, and counterparty still authorized.

7) Terminate cleanly

Define offboarding steps:

• Revoke credentials/keys, remove network rules, decommission endpoints.
• Confirm data retention and deletion expectations with third parties (where applicable).
• Update the register and retain closure evidence.

Required evidence and artifacts to retain

Auditors typically want both design evidence and operational evidence. Keep:

• CA-3 standard/procedure defining your organization parameters ¹.
• Information Exchange Register (current and historical snapshots).
• Approval records per exchange (tickets, sign-offs, risk acceptance).
• Data flow diagrams or architecture diagrams for key exchanges.
• Interface specifications (API specs, SFTP configs, federation metadata) and change history.
• Technical enforcement evidence: screenshots/exports from API gateway routes, firewall rules (with change ticket refs), IAM trust configs, key/cert management records.
• Logging/monitoring proof: sample logs, alert rules, and incident/ticket linkage for exchange-related events.
• Periodic review results and remediation actions for stale or risky exchanges.
• Termination evidence for decommissioned exchanges.

If you use Daydream, map CA-3 to a named control owner, a written procedure, and recurring evidence artifacts so collection is consistent across audits ¹.

Common exam/audit questions and hangups

Expect questions like:

• “Show me a list of all systems this system exchanges information with, including third parties.”
• “Pick one exchange and show the approval, the implemented mechanism, and the current configuration.”
• “How do you detect unauthorized exchanges?”
• “What triggers a re-approval? What triggers termination?”
• “How do you manage changes to APIs, credentials, keys, and allowlists?”
• “Where is this described in your SSP/control implementation statement?”

Hangups that cause findings:

• Inventory exists but is incomplete or outdated.
• Approvals exist but are not tied to technical change control.
• “We log everything” but cannot produce logs for a specific exchange and time window.
• Integrations via iPaaS/automation tools exist outside normal architecture review.

Frequent implementation mistakes (and how to avoid them)

1. Treating CA-3 as a one-time architecture diagram.
   Fix: require an exchange register entry plus a change ticket per exchange; enforce at creation points (gateway, firewall, IAM).

2. Forgetting identity and admin access paths.
   Fix: include federation, SCIM provisioning, VPN, VDI, and privileged portals in the exchange definition.

3. Approving “API access” without scoping data and permissions.
   Fix: approvals must state data categories and authorization scope (roles, endpoints, tables, folders).

4. No owner for the exchange after go-live.
   Fix: assign an integration owner and require periodic review attestations.

5. No clean termination process.
   Fix: add an offboarding checklist; test it by removing at least one stale exchange and retaining evidence.

Risk implications (why operators get burned)

Unmanaged exchanges create predictable failure modes: data exfiltration paths, over-permissioned third-party access, undocumented dependencies that break incident response, and untracked data sharing that complicates regulatory reporting. CA-3 reduces those risks by forcing explicit decisions, enforceable constraints, and traceable accountability ².

Practical 30/60/90-day execution plan

Use phases rather than dated promises. Adjust to your environment size and assessment timeline.

First 30 days (Immediate stabilization)

• Name a CA-3 control owner and backups.
• Publish the CA-3 procedure with your organization-defined parameters ¹.
• Stand up the Information Exchange Register with minimum fields.
• Capture the highest-risk exchanges first (those involving sensitive data, third parties, privileged access paths).

Days 31–60 (Operational control)

• Implement the intake/approval workflow in your ticketing system; require it for new exchanges.
• Tie approvals to technical enforcement points (API gateway, firewall, IAM, SFTP).
• Define standard exchange patterns and an exception path.
• Start periodic review for the riskiest exchanges and document outcomes.

Days 61–90 (Audit readiness)

• Run a completeness check: reconcile register vs. API gateway inventory, firewall rules, IAM trusts, and iPaaS connectors.
• Test evidence pull: for two exchanges, produce end-to-end proof (approval → config → logs).
• Terminate at least one stale exchange to prove offboarding works, and retain closure evidence.
• In Daydream, map CA-3 to the owner, procedure, and recurring evidence artifacts so audits become repeatable ¹.

Frequently Asked Questions

Does CA-3 apply only to external (third-party) connections?

No. CA-3 covers information exchange between your system and other systems, including internal systems and third parties ¹. Auditors typically sample both.

What counts as an “information exchange” in practice?

Any path where information moves across a system boundary: APIs, file transfers, identity federation, shared databases, remote admin access, and telemetry forwarding. Define your boundary and include both automated and manual transfer paths in scope.

How formal does “approve” need to be?

Formal means you can produce a record showing who approved the exchange, what was approved (data, purpose, mechanism), and when. A ticket with required approvers and attached technical details is usually the cleanest evidence.

We have too many integrations to document. Where do we start?

Start with the exchanges that move sensitive data or grant privileged access, and any exchange with a third party. Build the register iteratively, then reconcile against technical inventories to find the long tail.

How do we show we “manage” exchanges after approval?

Show lifecycle evidence: change tickets for modifications, periodic review attestations, monitoring/logging outputs tied to the exchange, and termination records when an exchange is retired. Management needs operational proof, not policy text.

Can Daydream help without changing our engineering tooling?

Yes. Keep engineering control points where they are (ticketing, IAM, network, gateways) and use Daydream to map CA-3 to an owner, document the procedure, and collect recurring evidence artifacts consistently ¹.

Footnotes

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

2. NIST SP 800-53 Rev. 5