CA-3(6): Transfer Authorizations

CA-3(6) requires you to verify that any user, service account, or system sending data into an interconnected system is authorized to write that data before the receiving system accepts it. Operationalize it by enforcing allow-listed identities, authenticated transfer paths, and destination-side authorization checks tied to explicit write privileges, then retain logs and approvals as evidence. ¹

Key takeaways:

• Validate write authorization at the receiving side, not just at the sender. ¹
• Treat “transfer” broadly: APIs, SFTP, message queues, ETL jobs, cross-account cloud writes, and third-party integrations.
• Evidence is usually the gap: you need configs, access reviews, and logs that prove the checks ran.

The ca-3(6): transfer authorizations requirement lives in the “System Interconnections” control area and targets a common failure mode: data gets accepted across a boundary because a connection exists, not because the sender has explicit write permission. The requirement is straightforward: before your system accepts inbound data from an interconnected system, it must verify that the transferring individual or system has the required authorizations, such as write privileges. ¹

For a CCO, GRC lead, or compliance officer, the fastest way to operationalize CA-3(6) is to translate it into two concrete questions: (1) “Who is allowed to write into this destination?” and (2) “How does the destination prove it checked?” This page gives you requirement-level implementation guidance you can hand to an IAM lead, integration engineer, or platform owner and get measurable progress quickly.

The practical scope is wider than “two networks connected.” Most environments now interconnect through APIs, SaaS apps, managed file transfer, event streaming, and cloud-to-cloud services. If inbound data can change records, trigger workflows, or land in a sensitive store, CA-3(6) applies.

Regulatory text

Requirement (verbatim): “Verify that individuals or systems transferring data between interconnecting systems have the requisite authorizations (i.e., write permissions or privileges) prior to accepting such data.” ¹

Operator interpretation (what you must do):

1. Identify inbound transfer paths between interconnected systems (including third parties) where data is written into your environment.
2. Define “requisite authorizations” for each destination (which roles, service accounts, certificates, or claims confer write permission).
3. Enforce a destination-side check so the receiving system accepts data only when the sender’s authenticated identity maps to an approved write authorization.
4. Prove it with evidence: configuration, approvals, and logs that show the authorization control exists and is operating. ¹

Plain-English interpretation (what CA-3(6) is really asking)

CA-3(6) is a gatekeeping requirement for data writes across system boundaries. If System A can send data to System B, System B must not accept the data just because the connection works. System B must confirm the sender is (a) identified and authenticated, and (b) authorized to write to that specific destination, using explicit privileges.

“Individuals or systems” covers:

• Human users uploading or syncing data
• Service accounts running jobs (ETL, batch, integrations)
• Workloads and apps posting to APIs or queues
• Third-party platforms pushing records into your systems

“Prior to accepting such data” is key: the control must run inline (or as a hard precondition), not as an after-the-fact detective review. ¹

Who it applies to

Entity scope

• Federal information systems and contractors handling federal data that adopt NIST SP 800-53 controls. ²

Operational scope (where you’ll find CA-3(6) obligations in practice)

• API integrations (partner APIs, internal microservices, SaaS webhooks)
• Managed file transfers (SFTP, FTPS, MFT tools, shared buckets used as “drop zones”)
• Event and message systems (queues, topics, streaming pipelines)
• Cloud cross-account writes (one account writing to another’s storage, logs, or databases)
• Third-party data feeds (benefits, payroll, KYC, threat intel, claims, EDI)

A quick scoping rule: if inbound data can create/modify records, execute actions, or land in a regulated dataset, treat it as in-scope for CA-3(6).

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

Step 1: Build an “Inbound Data Transfer Register”

Create a working list of inbound transfers that includes:

• Source system and owner (internal or third party)
• Destination system, dataset, and environment
• Transfer mechanism (API endpoint, bucket path, queue/topic, SFTP folder)
• Identity used (user, service account, workload identity, certificate)
• Write surface (what can be created/changed)

This register becomes your audit map for CA-3(6) coverage and your engineering backlog driver.

Step 2: Define the authorization model per destination

For each destination, document:

• Allowed writers (named roles/groups/service accounts)
• Least-privilege permissions required (write only to specific path/table/topic)
• Approval authority (system owner, data owner, security)
• Expiry/recertification expectation (tie to your access review cadence)

Keep this concrete. “Integration service account may write to /inbound/payroll/ only” is actionable. “Service accounts follow least privilege” is not.

Step 3: Enforce destination-side authorization checks

Implement controls that make the destination reject unauthorized writes. Common patterns:

• API gateway + IAM: Require mTLS/OAuth/JWT, map claims/scopes to allowed write operations, block by default.
• Bucket/object storage policies: Resource policies that allow writes only from specific principals and only to specific prefixes.
• Queue/topic ACLs: Producer permissions restricted to allow-listed identities; separate topics per sender when needed.
• SFTP/MFT: Per-sender accounts with chrooted directories and strict write permissions; no shared credentials.

Design rule: authorization must be verifiable and enforced at the receiving control point. That directly satisfies “prior to accepting such data.” ¹

Step 4: Add “transfer authorization” checks to change management

Require that new or changed interconnections cannot go live until:

• The sender identity is provisioned
• The destination-side policy is updated
• An approver signs off that the sender has requisite write authorization
• Logging/monitoring is enabled for accept/deny outcomes

This turns CA-3(6) from a one-time project into a repeatable operational control.

Step 5: Operational monitoring and exception handling

• Alert on denied writes that exceed a threshold you define (often indicates a misconfigured integration or attempted misuse).
• Review allow-lists on a defined cadence aligned to access reviews.
• Time-box exceptions (temporary write access should expire automatically).

Step 6: Assign ownership and make evidence recurring

CA-3(6) fails most often because no one owns it end-to-end. Assign:

• Control owner (GRC or Security Assurance)
• Technical owner(s) per destination platform (API, data platform, IAM)
• Evidence owner (who exports logs/configs for audits)

If you use Daydream to manage control ownership and recurring evidence tasks, map CA-3(6) to the system interconnection inventory, control procedure, and scheduled evidence pulls so audits don’t become an emergency. ¹

Required evidence and artifacts to retain

Keep artifacts tied to each interconnection (not generic program docs):

Governance artifacts

• Inbound Data Transfer Register (current and version history)
• System interconnection approvals (tickets, signed forms, or change records)
• Data owner approval that the sender is authorized to write (where data governance applies)

Technical configuration evidence

• IAM policies/role bindings showing who can write to the destination
• API gateway authorization policy (scopes/claims/allow rules)
• Storage resource policies (principal allow-list, prefix constraints)
• MFT/SFTP account configs (unique accounts, directory permissions)

Operational evidence

• Logs showing accepted and denied inbound writes, with sender identity
• Access review outputs for integration/service accounts that have write rights
• Exception register for temporary access, with expiry and approver

Auditors typically want to trace one interconnection end-to-end: approval → identity → policy → log output.

Common exam/audit questions and hangups

1. “Show me how the receiving system verifies authorization before accepting data.” Screenshots or exported policy configs help, but pair them with a plain-English explanation and a test case (authorized vs unauthorized).
2. “Do you have shared service accounts?” Shared credentials make it hard to prove “individuals or systems” are authorized. Expect scrutiny.
3. “How do you restrict writes to specific destinations?” Broad write permissions to an entire bucket or database are a common finding.
4. “How do you handle third-party integrations?” Auditors will ask whether the third party’s identity is uniquely represented and constrained on your side.
5. “Where is this documented per interconnection?” CA-3(6) is assessed at the interconnection level; a single policy statement rarely satisfies it. ¹

Frequent implementation mistakes and how to avoid them

Mistake	Why it fails CA-3(6)	Fix
Relying on network connectivity (VPN, peering) as “authorization”	Connectivity is not a write privilege	Add identity-bound authN/authZ at the destination control point 1
Shared integration credentials across senders	You cannot verify which “system” is authorized	Issue per-sender service principals/certs; separate permissions
Over-broad write permissions	Violates “requisite” least-privilege intent	Scope writes to specific endpoints/paths/tables/topics
No deny logging	You cannot prove verification occurred	Enable and retain decision logs (allow/deny) with identity context
Approval captured, but no technical enforcement	Paper control only	Make approvals drive policy-as-code changes and deployment gates

Enforcement context and risk implications

No public enforcement cases were provided for this specific enhancement in the supplied source material, so you should treat CA-3(6) as an assessment and authorization readiness requirement rather than a standalone enforcement trigger. The practical risk is still material: unauthorized inbound writes are a common precursor to data integrity issues, fraudulent transactions, and contamination of regulated datasets. CA-3(6) reduces that risk by forcing explicit write authorization at interconnection boundaries. ¹

Practical 30/60/90-day execution plan

First 30 days (stabilize scope and owners)

• Assign a control owner and technical owners per major destination type (APIs, storage, queues, MFT).
• Build the first version of the Inbound Data Transfer Register focused on high-risk destinations (regulated data stores, production systems).
• Pick a standard pattern per transfer type (for example, “all APIs must use gateway authZ; all buckets must enforce resource policies”).

Days 31–60 (implement enforcement on the biggest write surfaces)

• Retrofit destination-side authorization checks for the top inbound transfers by risk and volume.
• Eliminate shared integration credentials for those transfers.
• Add change-management gates: “no new interconnection without destination-side authZ evidence.”

Days 61–90 (prove operation and make it repeatable)

• Run an access review for integration identities with write permissions to in-scope destinations.
• Produce an “audit packet” for a sample of interconnections: approval → policy → logs.
• Automate recurring evidence pulls where possible (policy exports, log samples, access review outputs). Daydream can track these artifacts and owners so you can respond quickly during assessments. ¹

Frequently Asked Questions

Does CA-3(6) apply to internal microservices, or only to third parties?

It applies to any “interconnecting systems,” including internal systems. If Service A can write data into Service B, Service B must verify Service A’s write authorization before accepting the data. ¹

Is authentication enough, or do we need explicit authorization too?

You need authorization tied to write privileges. Authentication proves who the sender is; CA-3(6) requires verifying they have the requisite write permissions before accepting the data. ¹

What counts as “accepting” data for event streams or queues?

Treat publish/produce permission as the acceptance gate. The destination queue/topic must enforce producer authorization so unauthorized senders cannot place messages that downstream consumers treat as valid.

We have a VPN between environments. Can that satisfy the requirement?

A VPN can be part of the security design, but CA-3(6) calls for verifying write authorizations. You still need identity-based permissions at the destination (API, bucket, database, queue) that restrict who can write. ¹

How do we handle inbound files dropped into a shared folder by multiple teams?

Shared drop zones are a common audit finding. Use per-sender accounts and separate directories/prefixes with explicit write permissions, then log accept/deny events tied to the sender identity.

What’s the minimum evidence an auditor will accept for one interconnection?

Provide (1) the approved request/change record naming the sender identity, (2) the destination-side policy showing write rights, and (3) logs demonstrating the system enforces and records authorization decisions. ¹

Footnotes

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

2. NIST SP 800-53 Rev. 5