CA-3(3): Unclassified Non-national Security System Connections

CA-3(3) requires you to explicitly control and document connections between your unclassified, non‑national security systems and any external systems or networks, so those interconnections are authorized, bounded, and continuously governed. Operationalize it by building an interconnection inventory, approving each link through a formal process, and retaining evidence that the connection is necessary, secure, and monitored. ¹

Key takeaways:

• Maintain a complete inventory of external connections for each in-scope unclassified system and keep it current.
• Require formal authorization for each interconnection, with defined boundaries, responsible owners, and security conditions.
• Keep durable evidence (agreements, diagrams, approvals, test results, monitoring) so you can prove the connection is governed.

The ca-3(3): unclassified non-national security system connections requirement is a governance control that becomes painful only when you treat it as paperwork. Your real objective is to prevent “shadow interconnections” (APIs, VPNs, B2B tunnels, cloud-to-cloud links, cross-domain file transfers, shared admin tooling) from bypassing risk decisions. CA-3(3) sits in the NIST SP 800-53 assessment and authorization family, so auditors expect you to show that interconnections are identified, approved, and managed as part of your system’s authorized operating state. ¹

For a Compliance Officer, CCO, or GRC lead, the fastest path is: define what counts as a connection, centralize the inventory, implement a gate that blocks new interconnections without review, and then run recurring checks so the inventory stays accurate. If you already run third-party risk management, treat each external connection as both a technical pathway and a third-party dependency with an accountable business owner, a security owner, and clear termination steps.

Regulatory text

Excerpt (as provided): “NIST SP 800-53 control CA-3.3.” ²

Operator interpretation: CA-3(3) expects you to manage interconnections for unclassified, non‑national security systems so that any external connection is known, explicitly approved, and governed with defined terms and security conditions. The operational test is simple: can you prove every external connection is authorized, controlled, and reviewed as part of normal operations, not discovered during an incident response scramble? ¹

Plain-English meaning

• If your system connects to anything outside its authorization boundary (another system, another network segment owned by a different organization, a third-party service, a partner environment), you need a documented decision that the connection is allowed and under what conditions.
• “Unclassified non-national security system” means the system is not a national security system, but still requires disciplined connection governance under NIST SP 800-53 expectations. ¹

Who it applies to

Entities

• Federal information systems implementing NIST SP 800-53 controls. ¹
• Contractor systems handling federal data where NIST SP 800-53 is contractually required or used as the governing control framework. ¹

Operational scope: what counts as a “connection”

Treat these as in-scope interconnections unless you have a documented rationale otherwise:

• Site-to-site VPNs, partner tunnels, dedicated circuits, peering.
• Cloud interconnects (VPC/VNet peering, private endpoints), SaaS-to-SaaS integrations.
• API integrations that move or expose federal data or administrative control.
• Shared identity and admin planes (SSO connections, directory sync, privileged access tooling).
• Data exchange mechanisms (SFTP endpoints, message queues, EDI, file transfer appliances).

A practical rule: if compromise of the external party or pathway could create a confidentiality/integrity/availability impact for the system, treat it as an interconnection that must be authorized and governed.

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

1) Define your “interconnection” standard (so teams stop arguing)

Create a one-page internal standard that answers:

• What is an interconnection vs. normal internet access?
• What is “external” (other internal business unit, shared services, third party, partner)?
• What minimum security conditions must exist (authentication, encryption, logging, monitoring, incident notification)?
• What is the required approval path (business owner + system owner + security)?

This is where most programs fail: no crisp definition, so the inventory is permanently incomplete.

2) Build (or fix) the interconnection inventory

Stand up a canonical register. Minimum fields:

• System name and owner (authorizing/approving official or delegated system owner).
• Connection name, type (VPN, API, peering, file transfer), and purpose.
• External organization / third party, including service name and support contact.
• Data types accessible or transferred (high-level categories).
• Authentication method, encryption method, and network path.
• Boundary diagram reference (link to current architecture diagram).
• Approval record (date, approvers, conditions).
• Review cadence and next review date.
• Termination plan (how to shut it off, who executes).

If your environment changes fast, don’t depend on spreadsheets alone. Many teams keep the register in GRC and reconcile it against technical sources (cloud routing tables, API gateway configs, firewall rulesets, IAM federation lists).

3) Require an “interconnection package” for every connection

For each connection, collect a lightweight but complete set of decision inputs:

• Business justification and necessity.
• Proposed architecture and boundary impact.
• Data flows (what crosses, directionality, where it is stored).
• Security requirements (identity, encryption, segmentation, logging).
• Third-party assurance inputs (contract clauses, security addendum, incident notification obligations).

This package becomes your audit-ready proof that the connection did not appear informally.

4) Approve and document authorization conditions

Create an approval workflow with explicit outcomes:

• Approved (conditions met).
• Approved with conditions (remediation tasks and deadlines owned by someone).
• Rejected (and the technical implementation is blocked or removed).

Tie conditions to enforceable controls (for example: “Connection must terminate in a dedicated subnet with firewall policy X,” “API must use mTLS and scoped tokens,” “Logs must feed SIEM with alerts”).

5) Implement technical guardrails so approvals matter

Auditors will compare your documented process to reality. Common guardrails:

• Network segmentation and egress controls to prevent unmanaged outbound tunnels.
• Change management hooks: new VPN, new peering, new API route requires a ticket with the interconnection ID.
• Centralized identity and key management for interconnection credentials.
• Monitoring: connection health, anomalous traffic, failed authentication spikes.

Your goal is to make the “approved register” the source of truth that engineering must reference.

6) Recurring reviews and continuous reconciliation

CA-3(3) fails quietly over time when inventories drift. Put recurring checks in place:

• Revalidate business need and data scope.
• Confirm technical configuration matches the documented boundary and conditions.
• Confirm the third party relationship is still active and contract terms still apply.
• Retire dead connections aggressively (stale tunnels are a common exposure).

7) Map ownership, procedure, and recurring evidence (minimum viable compliance)

A practical control mapping is the fastest way to operationalize CA-3(3):

• Control owner: GRC lead (process), Network/Security Engineering (technical enforcement), System Owner (risk acceptance).
• Procedure: documented intake → security review → approval → implementation → monitoring → periodic review.
• Recurring evidence: inventory export, approval tickets, architecture diagrams, review attestations, monitoring reports. ²

Daydream (used as a GRC workflow layer) can help by assigning a single owner, capturing the procedure steps, and generating recurring evidence checklists tied to each interconnection record, so your team stops rebuilding artifacts for every assessment.

Required evidence and artifacts to retain

Keep artifacts in a structured foldering scheme per system and per connection:

1. Interconnection inventory extract (current and prior versions for change tracking)
2. Network/data flow diagrams showing boundaries and trust zones
3. Approval records (tickets, signed memos, workflow approvals)
4. Security requirements and configurations (firewall rules, IAM federation settings, API gateway policies)
5. Third-party agreements relevant to the connection (security addendum, incident notification, data handling)
6. Testing and validation (connectivity tests, security test results relevant to the connection)
7. Monitoring evidence (logs routed to SIEM, alert rules, sample alerts, periodic review notes)
8. Termination/rollback plan and evidence of decommissioning for retired connections

Common exam/audit questions and hangups

Expect these, and pre-answer them with your artifacts:

• “Show me all external connections for System X and who approved each one.”
• “Which connections allow administrative access or privileged pathways?”
• “How do you prevent teams from creating new connections outside the process?”
• “How do you know your inventory is complete?” (They will ask about discovery and reconciliation.)
• “Show evidence of periodic review and removal of unused connections.”
• “How do third-party contract terms map to security conditions for the connection?”

Hangup to avoid: producing a policy but no proof that the policy drives engineering behavior.

Frequent implementation mistakes (and how to avoid them)

1. Treating “the internet” as the only external network.
   Fix: include cloud-to-cloud, identity federation, and API integrations as first-class interconnections.

2. No authoritative inventory owner.
   Fix: assign one accountable owner per system and one program owner for the register; require updates via change management.

3. Approvals that don’t bind configuration.
   Fix: connect approval IDs to firewall objects, VPN profiles, API gateway routes, and IaC repositories.

4. Over-scoping evidence.
   Fix: keep a consistent “interconnection package” template. Collect what supports decisions, not every possible artifact.

5. No offboarding path.
   Fix: require a termination method and responsible engineer before approval. Dead connections accumulate fastest in partner integrations.

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for this requirement, so you should treat CA-3(3) primarily as an assessment-readiness and risk-governance control rather than a control with a specific penalty history in this dataset. ¹

Risk-wise, unmanaged interconnections create two recurring failure modes:

• Boundary erosion: the authorized system boundary becomes meaningless if external pathways bypass governance.
• Third-party pathway risk: a third party’s compromise becomes your incident through a persistent connection.

A practical 30/60/90-day execution plan

First 30 days (stabilize and stop new risk)

• Publish the interconnection definition and minimum approval requirements.
• Stand up the interconnection register with required fields.
• Put an interim gate in change management: “No new external connection without an interconnection record ID.”
• Identify the top critical connections (admin access, bulk data flows) and ensure they have an owner and an approval record.

By 60 days (make it auditable)

• Complete inventory coverage for in-scope systems using technical discovery inputs (firewalls, cloud routing/peering lists, IdP federation lists).
• Implement the interconnection package template and required approvals.
• Attach diagrams and data flows for each critical connection.
• Document monitoring expectations and confirm log routing for critical pathways.

By 90 days (make it durable)

• Run the first periodic review cycle and document outcomes (renew, modify, retire).
• Reconcile the register against technical configuration and close gaps.
• Add termination evidence for at least one retired connection (prove you can shut things off cleanly).
• Operationalize recurring evidence collection in your GRC workflow (Daydream or your current platform) so assessments become exports, not scrambles.

Frequently Asked Questions

Does CA-3(3) apply if we only use SaaS and don’t manage network gear?

Yes, because SaaS-to-SaaS integrations, identity federation, and admin access pathways are still external connections that need authorization and governance. Track them in the same register and tie approvals to configuration evidence. ¹

What is the difference between an interconnection and ordinary outbound internet access?

Ordinary web browsing from user endpoints is usually handled through standard boundary protections. An interconnection is a purposeful, persistent, or privileged pathway (VPN, peering, API integration, federation) that extends trust or moves controlled data across boundaries. ¹

Do we need a signed “ISA” for every connection?

NIST language in this dataset does not mandate a specific document name for CA-3(3). What matters is that you have documented authorization, defined security conditions, and retained evidence that the conditions match the implemented connection. ²

How do we prove our interconnection inventory is complete?

Use reconciliation: compare the register to technical sources (cloud peering lists, VPN configs, API gateways, IdP federation apps) and retain evidence of that comparison. Auditors accept completeness claims when you show a repeatable method and results.

Who should approve an interconnection?

Require approval from the system owner (risk acceptance), security (control requirements), and the business owner (justification and impact). For high-risk connections, route to the authorizing official or equivalent authority in your governance model. ¹

What evidence is “most valuable” during an audit?

A current register, clear diagrams, and approval records tied to actual configurations carry the most weight. Add periodic review notes and monitoring proof to show the control operates continuously, not only during project delivery.

Footnotes

1. NIST SP 800-53 Rev. 5

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