Dependency Identification

“Dependency identification requirement” sounds simple until you try to run an incident or audit and realize nobody can answer basic questions: Which third parties support the control room network? Who runs the managed firewall? Which cloud services host outage communications? What subcontractors sit behind your prime vendor?

C2M2’s requirement is short, but the operational intent is clear: you must identify dependencies on external entities for the delivery of the function. (Cybersecurity Capability Maturity Model v2.1) For a CCO or GRC lead, this is less about producing a spreadsheet and more about creating a reliable operating picture: the third parties, the services they provide, how they connect into your environment, and which business/operational outcomes depend on them.

This page gives you requirement-level implementation guidance you can execute quickly: scope, roles, step-by-step build instructions, the evidence auditors ask for, and common failure points. The goal is a dependency inventory that supports procurement, risk assessments, incident response, and resilience planning without boiling the ocean.

Regulatory text

Requirement (C2M2 THIRD-PARTIES-1.A, MIL1): “Dependencies on external entities for the delivery of the function are identified.” (Cybersecurity Capability Maturity Model v2.1)

Operator interpretation: You must be able to enumerate the external entities (third parties) that your function relies on, and do it in a way that supports decisions and response actions. A static vendor master list is rarely sufficient because it often misses:

• Non-procured dependencies (telecom carriers, cloud platforms, upstream utilities)
• “Hidden” dependencies (subprocessors, subcontractors, data center operators)
• Operational dependencies (field service contractors, OEM support, managed service providers)
• Product and service dependencies (software publishers, patching channels, certificate authorities)

What an assessor looks for at MIL1: Evidence that you have identified dependencies. At this maturity level, completeness and accuracy matter more than sophisticated scoring.

Plain-English requirement: what it means in practice

You meet this requirement when you can answer, for each critical function you operate:

1. Which third parties are required to deliver it, support it, or recover it.
2. What each third party provides (service/product/support) and who in your organization owns that relationship.
3. Where and how the third party connects to your systems, facilities, or data.
4. What breaks if they fail (operational impact), so incident response and continuity plans are grounded in reality.

If you cannot connect “critical function → dependencies → systems/data → failure modes,” you have an inventory, not dependency identification.

Who it applies to

Entity types: Energy sector organizations and other critical infrastructure operators adopting C2M2. (Cybersecurity Capability Maturity Model v2.1)

Operational contexts where this requirement usually bites hardest:

• OT environments with OEM remote support and integrators
• Managed security services and shared infrastructure (SOC, SIEM, endpoint tooling)
• Cloud-hosted customer portals, outage communications, or analytics platforms
• Telecom and network transport supporting dispatch/control communications
• Outsourced field services, vegetation management, maintenance, and emergency response vendors

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

Step 1: Set the scope around “functions,” not procurement categories

Define the functions you care about first (often your “critical functions” list). For each function, decide what “delivery” means: run, monitor, maintain, and recover. Then inventory dependencies across that lifecycle.

Output: Function list with an executive owner, plus a statement of what “delivery of the function” includes for your org. (Cybersecurity Capability Maturity Model v2.1)

Step 2: Build a dependency taxonomy your teams can use

Keep it simple so it gets adopted. A workable minimum set:

• Third party type: vendor, contractor, partner, service provider, supplier, government/utility dependency
• Dependency category: technology/service, operational service, data/service hosting, connectivity, support/maintenance, supply chain/OEM
• Criticality: supports a critical function (yes/no), and whether it is single-point-of-failure for that function

Tip from practice: If you try to model every nuance up front, business owners disengage. Start with a small required field set and expand later.

Step 3: Create the dependency register (the core artifact)

Your register should be a living system of record, not a once-a-year spreadsheet. Minimum fields to make it operational:

Field	Why it matters
Third party legal name + service name	Prevents confusion across affiliates and products
Supported function(s)	Proves the dependency is tied to delivery of a function
Service description (plain language)	Enables non-procurement teams to validate
Relationship owner (business) + risk owner (GRC)	Creates accountability for updates and decisions
System(s)/asset(s) touched	Bridges third-party risk to your environment
Data types involved	Drives downstream assessment scope
Access/connection method	Remote access and integration points are common risk drivers
Subcontractors/subprocessors (if known)	Captures hidden dependencies
Contract/SOW reference	Proves the dependency is real and traceable
Last validated date + validation method	Shows it is maintained

Step 4: Identify dependencies using multiple discovery paths

Do not rely on one source. Use at least these discovery paths and reconcile them:

• Procurement/AP extract: paid suppliers and service providers
• IT/OT architecture: network diagrams, remote access gateways, VPN lists, jump hosts
• Identity logs: third-party accounts, federated SSO, privileged access groups
• CMDB/asset inventories: managed devices, hosted workloads, SaaS tenants
• Business owner workshops: “what do you call at 2 a.m. when this breaks?”
• Incident postmortems: third parties involved in recent outages or security events

Control objective: Every dependency in the register can be traced back to evidence (invoice, contract, system integration, access path, or owner attestation). (Cybersecurity Capability Maturity Model v2.1)

Step 5: Validate completeness with “failure mode” questions

For each critical function, run a short validation:

• If this third party is unavailable, what fails first?
• Can the function still operate in a degraded mode?
• Do you have an alternate provider, manual fallback, or stockpile?
• What is the maximum tolerable downtime from an operational standpoint (capture qualitatively if you do not have formal tolerances)?

This converts a list into an operational dependency view.

Step 6: Operationalize updates through change management

Dependency identification breaks the moment new services are onboarded outside standard procurement or IT processes.

Add triggers so the register stays current:

• New contract/SOW, renewal, termination
• New connectivity method (VPN, API, remote tool)
• New data sharing or hosting arrangement
• New subcontractor/subprocessor disclosed
• Major architecture changes to the supported function

Good practice: Make “register update complete” a gate for go-live or renewal approval.

Step 7: Embed ownership and review cadences

Assign:

• Function owner: validates “what we depend on” for the function
• Third-party relationship owner: accountable for supplier-facing updates
• GRC: ensures the process exists, evidence is retained, and exceptions are tracked

If you want this to move fast, Daydream can act as the system of record for dependency mapping by linking third parties to functions, systems, and evidence in one place, so updates and audits do not become email archaeology.

Required evidence and artifacts to retain

Keep artifacts that prove identification, traceability, and maintenance:

1. Dependency register (current export plus historical versions)
2. Method/procedure describing how dependencies are identified and kept current (Cybersecurity Capability Maturity Model v2.1)
3. Data sources used (AP extract, CMDB reports, access lists) and reconciliation notes
4. Owner attestations for each critical function (“these are the dependencies as of [date]”)
5. Architecture evidence where relevant (network diagrams, integration inventories, remote access inventories)
6. Contracts/SOW references tied to each dependency entry
7. Change management records showing updates triggered by onboarding/changes/renewals

Common exam/audit questions and hangups

Expect questions like:

• “Show me all external dependencies for this critical function.” (Cybersecurity Capability Maturity Model v2.1)
• “How do you know this list is complete?”
• “How are subcontractors captured?”
• “Where do third parties have remote access, and who approved it?”
• “How do you keep the inventory current between annual reviews?”

Hangups that slow audits:

• Dependency list is not tied to functions (only to spend categories)
• Multiple competing lists with no system of record
• No named owners, so updates are informal
• Inability to show evidence that discovery was performed beyond procurement exports

Frequent implementation mistakes (and how to avoid them)

1. Mistake: treating dependency identification as vendor management.
   Fix: Inventory dependencies that are not “vendors” (carriers, OEM portals, cloud platforms, emergency mutual aid partners) and map them to functions.

2. Mistake: missing access pathways.
   Fix: Require an “access/connection method” field and validate against VPN, remote support tools, API gateways, and identity inventories.

3. Mistake: ignoring fourth parties.
   Fix: Add a field for known subcontractors/subprocessors and require relationship owners to capture what is disclosed during onboarding and renewals.

4. Mistake: no operational definition of “delivery of the function.”
   Fix: Define delivery as run/monitor/maintain/recover for each critical function, then inventory dependencies across that lifecycle. (Cybersecurity Capability Maturity Model v2.1)

Enforcement context and risk implications

No public enforcement cases were provided in the source catalog for this requirement. Practically, the risk is straightforward: unidentified dependencies become blind spots during cyber incidents, operational disruptions, and regulatory examinations. You cannot manage third-party risk, resilience, or recovery for relationships you have not identified. (Cybersecurity Capability Maturity Model v2.1)

Practical 30/60/90-day execution plan

First 30 days (Immediate)

• Name an executive sponsor and a single owner for the dependency register.
• Confirm the list of critical functions in scope and the definition of “delivery.”
• Stand up the register with minimum fields and pick the system of record.
• Run discovery for a small set of the highest-impact functions using procurement + IT/OT architecture + access inventories. (Cybersecurity Capability Maturity Model v2.1)

By 60 days (Near-term)

• Expand function workshops to complete initial identification across remaining critical functions.
• Add change-management triggers (onboarding, renewal, connectivity change).
• Require business owners to attest to their function’s dependency list and resolve gaps.
• Pilot reporting: “dependencies per function” and “third parties with remote access.” (Cybersecurity Capability Maturity Model v2.1)

By 90 days (Operationalized)

• Formalize the written procedure and make it part of third-party onboarding and architecture review.
• Implement a recurring validation motion owned by function leaders (supported by GRC).
• Close “hidden dependency” gaps by requiring subcontractor/subprocessor disclosures during renewals and documenting what is known.
• Test the register in a tabletop: pick one critical function, simulate third-party failure, and validate the list supports decisions. (Cybersecurity Capability Maturity Model v2.1)

Frequently Asked Questions

Do we have to identify every supplier, or only those tied to critical functions?

The requirement is framed around “delivery of the function,” so start with dependencies required for your in-scope functions. Many teams begin with critical functions and expand later as the process stabilizes. (Cybersecurity Capability Maturity Model v2.1)

Is a vendor master list enough to satisfy dependency identification?

Usually no. A vendor master list rarely shows what function is supported, how the third party connects, or what breaks if the third party fails. Add function mapping and connection points to make it defensible. (Cybersecurity Capability Maturity Model v2.1)

How do we handle cloud providers where we have no direct contract (reseller or embedded service)?

Record the dependency anyway and tie it to the function and system. Capture the contracting path (reseller/prime) and any known subprocessors so you can assess the real operational dependency.

What’s the minimum evidence auditors expect at this maturity level?

A current dependency register, a repeatable identification method, and proof you used real sources (procurement, architecture, access lists) rather than informal memory. Owner accountability and update triggers make the evidence stronger. (Cybersecurity Capability Maturity Model v2.1)

Who should “own” dependency identification: procurement, IT, or GRC?

Put day-to-day ownership with the function/business relationship owners because they know what is required to deliver the function. GRC should set standards, verify evidence, and drive consistency across functions. (Cybersecurity Capability Maturity Model v2.1)

How do we keep the register current without creating a bureaucratic bottleneck?

Make updates event-driven through onboarding, renewal, and architecture/change gates, and keep required fields minimal. A single system of record (including tools like Daydream) reduces duplicate data calls and version sprawl.