Interconnected Business Information Systems

HITRUST CSF v11 09.w requires you to control and document every interconnection between your business information systems and any other internal network, customer environment, or third party. You must implement written policies and procedures, and execute interconnection agreements that spell out security requirements, access controls, and data protection duties for each connected party. ¹

Key takeaways:

• Treat every system-to-system connection as a governed relationship with named owners, approved purpose, and defined security controls.
• Require a signed interconnection agreement (or equivalent contract addendum) before production connectivity.
• Evidence matters: auditors look for an inventory of interconnections, approvals, and technical enforcement that matches the paperwork.

“Interconnected business information systems” sounds abstract until you map it to real operations: SFTP feeds to a claims processor, VPN access for a managed service provider, APIs to a billing platform, HL7 connections to a hospital, or a direct network link between business units. Each connection expands your attack surface and introduces shared responsibility gaps (“we thought they were logging,” “they thought we were encrypting”). HITRUST CSF v11 09.w closes that gap by forcing two things: (1) you run interconnections under policy and procedure, and (2) you bind connected parties to explicit security, access control, and data protection obligations through an interconnection agreement. ¹

For a Compliance Officer, CCO, or GRC lead, the fastest path to operationalizing this requirement is to stand up a single, repeatable intake-and-approval workflow that produces consistent artifacts: an interconnection inventory, a risk review, a standardized agreement package, and technical control verification. The goal is not more paperwork; it’s alignment between what’s connected, what data flows, who can access what, and what protections are enforced on both sides.

Regulatory text

HITRUST CSF v11 09.w states: “Policies and procedures shall be developed and implemented to protect information associated with the interconnection of business information systems. Interconnection agreements shall define the security requirements, access controls, and data protection obligations for each connected party.” ¹

Operator translation:
You need (a) a written, implemented program for governing system interconnections, and (b) written agreements for each interconnection that clearly assign security responsibilities, limit and control access, and define data protection requirements across both parties.

Plain-English interpretation (what the requirement is really testing)

Auditors and assessors are looking for proof that you can answer, consistently and with evidence:

1. What is connected to what? (Inventory and architecture visibility)
2. Why is it connected? (Business purpose, approved scope, and least privilege)
3. What data crosses the boundary? (Data classification, permitted use, retention, and deletion)
4. Who is responsible for which controls? (Shared responsibility defined contractually)
5. Are controls enforced technically? (Network segmentation, authentication, logging, encryption, monitoring)

If your contracts say “MFA required” but the connection uses shared local credentials, you fail on implementation. If your network team built a tunnel but there’s no agreement defining obligations, you fail on governance.

Who it applies to

Entity types: All organizations aligning to HITRUST CSF. ¹

Operational context (where this shows up):

• Third-party connectivity: vendor VPNs, MSP remote admin tools, outsourced call centers, data processors, managed hosting, SOC providers.
• Customer and partner connections: customer-owned SSO/IdP integration, B2B APIs, EDI gateways, payer/provider connectivity.
• Internal interconnections: mergers/acquisitions, shared services, inter-network links between environments (corp to prod, prod to analytics).
• Cloud and SaaS integrations: direct connect/peering, private endpoints, service-to-service API keys, event streaming to external platforms.

If it creates a path for access to your systems or moves your data across a trust boundary, treat it as an “interconnection” under 09.w.

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

1) Define scope and ownership

• Appoint a control owner in Security/GRC and require system owners for each side of the connection.
• Define what counts as an interconnection in your environment (examples above) and publish it in your policy.

Deliverable: Interconnection policy + procedure that includes definitions, required reviews, and approval gates. ¹

2) Build and maintain an interconnection inventory (the backbone)

Create a living register with, at minimum:

• Connection name/ID, systems involved, environments (prod/non-prod)
• Connected party (internal BU, customer, third party)
• Connection type (API, VPN, SFTP, peering, SaaS integration)
• Data types transferred and classification
• Authentication method (certs, SSO, keys), authorization model, privileged access involved
• Network path (CIDRs, ports, segmentation/zone)
• Logging/monitoring owner and log destination
• Encryption method (in transit and, if relevant, at rest on endpoints)
• Start date, end/renewal date, last review date, approvers

Tip: If you can’t inventory it, you can’t govern it. Most teams discover “shadow interconnections” by reconciling firewall rules, VPN configs, API gateways, and integration platform connectors against the register.

3) Standardize the interconnection intake workflow

Require an intake before any production connectivity. Intake should capture:

• Business purpose and requested go-live date
• Systems, data, users/service accounts, and admin functions needed
• Threat model questions (internet-facing? persistent tunnel? third party managed?)
• Required controls checklist (MFA, IP allowlisting, encryption, logging, vuln mgmt expectations)

Approval gates to include:

• System owner approval
• Security architecture review (network segmentation, identity, monitoring)
• Privacy review if regulated data is involved
• Third-party risk review if an external party is involved
• Change management approval for implementation

4) Require an interconnection agreement (or equivalent) per connection

HITRUST calls out “interconnection agreements” explicitly. ¹ In practice, this can be:

• A standalone interconnection agreement,
• An MSA + security addendum + data protection addendum that is connection-specific, or
• A customer connectivity exhibit that governs the integration.

Minimum clauses to include (mapped to the requirement):

• Security requirements: baseline security program expectations, incident reporting duties, vulnerability handling coordination, patch expectations for devices used to access the connection.
• Access controls: identity proofing, MFA requirement, least privilege, privileged access restrictions, service account controls, joiner/mover/leaver responsibilities, periodic access review expectations.
• Data protection obligations: permitted use, data handling and retention, encryption expectations, restrictions on onward transfer/subprocessors, secure disposal, breach notification expectations.

Shared responsibility table (strongly recommended):
Put a simple RACI-style matrix in the agreement or exhibit. Auditors like clarity more than prose.

5) Implement technical controls that match the agreement

Common technical expectations that should align with your stated requirements:

• Network segmentation and firewall rules restricted to required ports and destinations
• Strong authentication (SSO/MFA where feasible; cert-based auth for system-to-system)
• Secrets management for API keys/certs; rotation process
• Central logging for access and data movement events; alerting for anomalous access
• Encryption in transit for inter-system data transfers
• Monitoring ownership defined (who responds at 2 a.m. and how)

Control test mindset: If you cannot demonstrate enforcement (configs, screenshots, logs, change tickets), assume it will be graded as incomplete.

6) Operate: review, attest, and offboard

• Periodically review each interconnection for continued need, scope creep, and access drift.
• Reconfirm the agreement is still in force (renewals, DPAs, subprocessors).
• Offboard cleanly: disable tunnels, revoke certs/keys, remove firewall objects, confirm data return/destruction where applicable.

Required evidence and artifacts to retain

Auditors typically ask for a sample of interconnections and want end-to-end proof. Maintain:

• Interconnection policy and procedure (approved, versioned, communicated) ¹
• Interconnection inventory/register with owners and status
• Completed interconnection intake forms and risk reviews
• Signed interconnection agreements (or contract exhibits) for sampled connections ¹
• Architecture diagrams/data flow diagrams for high-risk connections
• Access control evidence: MFA settings, SSO configs, role mappings, access review records
• Network/security evidence: firewall rules, VPN configs, allowlists, change tickets
• Logging/monitoring evidence: SIEM ingestion, alerts, sample logs, incident runbooks
• Offboarding records: decommission tickets, key revocation evidence

Practical retention tip: Store these in a single “connection package” folder per interconnection so sampling does not turn into a scavenger hunt.

Common exam/audit questions and hangups

• “Show me your inventory of interconnected systems. How do you know it’s complete?”
• “Pick one third-party connection. Where is the agreement defining access controls and data protection?”
• “Who approves a new interconnection, and where is that documented?”
• “Does the technical configuration enforce what the agreement requires (MFA, encryption, logging)?”
• “How do you terminate access when the relationship ends or scope changes?”
• “How do you handle subcontractors or downstream connections tied to this interconnection?”

Hangup: teams present a generic MSA with security language but nothing connection-specific (ports, identities, data types). That often fails the “define obligations for each connected party” expectation. ¹

Frequent implementation mistakes (and how to avoid them)

1. No single source of truth for interconnections.
   Fix: mandate registration as part of change management; reconcile quarterly against firewall/VPN/API gateway inventories.

2. Agreements exist, but they’re generic.
   Fix: add a connectivity exhibit template with a responsibility matrix, named systems, and control requirements tied to the actual integration.

3. “Temporary” connections become permanent.
   Fix: require an owner, an expiry, and a review trigger; block renewals without re-approval.

4. Service accounts and keys are unmanaged.
   Fix: require secrets storage, rotation ownership, and logging for token/cert use. Make “no shared credentials” a default.

5. Monitoring is assumed, not assigned.
   Fix: name the monitoring owner and define what gets alerted. Put it in the connection package and the agreement.

Enforcement context and risk implications

No public enforcement cases were provided in the available source catalog for this requirement, so this page does not list specific cases.

Operationally, this control reduces two recurring failure modes: (1) unclear shared responsibility during security incidents, and (2) unmanaged connectivity paths that bypass standard access controls. If you process sensitive data, interconnections also drive downstream breach exposure because attackers often enter through the weakest connected party, then move laterally across trusted links.

Practical 30/60/90-day execution plan

First 30 days (stabilize and get visibility)

• Publish an “interconnection” definition and interim rule: no new production interconnections without Security/GRC approval. ¹
• Stand up an interconnection register and populate it from known sources (network team, IAM, integration platform, cloud networking, procurement).
• Create the intake form and a lightweight review meeting cadence.
• Draft the interconnection agreement/exhibit template with Legal, Security, Privacy, and Procurement. ¹

Days 31–60 (standardize and retrofit the highest-risk connections)

• Rank interconnections by risk (sensitive data, privileged access, persistent tunnels, internet exposure).
• Retrofit the agreement for top-risk interconnections first; document compensating controls where you cannot renegotiate quickly.
• Align technical enforcement to the template (MFA, segmentation, logging, key management), and attach evidence to each connection package.
• Train requesters and system owners on the workflow; make it part of change management.

Days 61–90 (operate like it’s steady-state)

• Require periodic review and re-attestation by connection owners.
• Build reconciliation: compare register vs firewall rules/VPN lists/API gateway integrations and open tickets for gaps.
• Test the program with an internal audit-style sample: can you produce the full package in one sitting?
• If you use Daydream, configure a third-party connectivity workflow that ties together intake, risk review, contract artifacts, and evidence collection so each interconnection stays audit-ready without chasing teams by email.

Frequently Asked Questions

What counts as an “interconnection” under HITRUST 09.w?

Any system-to-system connection that crosses a trust boundary and enables access or data transfer between business information systems. That includes VPNs, APIs, SFTP feeds, private network links, and SaaS-to-SaaS integrations. ¹

Do we need a separate interconnection agreement for every connection if we already have an MSA?

You need an agreement mechanism that defines security requirements, access controls, and data protection obligations for each connected party. Many teams meet this by adding a connection-specific exhibit or addendum under the MSA that documents the exact integration scope. ¹

How do we handle customer-required interconnections where the customer won’t sign our template?

Use their paper if needed, but ensure the final executed terms still cover the three required areas: security requirements, access controls, and data protection obligations. If a gap remains, document compensating controls and internal approvals before connecting. ¹

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

A signed agreement or exhibit, an approval trail, a description of the systems and data flows, and proof that access controls and protections are actually enforced (configs and logs). If any of those are missing, expect a finding. ¹

Our interconnection is “read-only.” Do we still need the same rigor?

Yes. Read-only connections still expose sensitive data and can become a pivot point for attackers if identity, network scope, or monitoring is weak. Scope can be smaller, but governance and agreement requirements still apply. ¹

Who should own the interconnection inventory: Security, IT, or Procurement?

Assign a single accountable owner (often Security/GRC), but feed it from the teams that create and operate connectivity (network, IAM, integration engineering, cloud platform) and from Procurement/Legal for the agreement artifacts.

Footnotes

1. HITRUST CSF v11 Control Reference