Asset Inventory Prioritization

Asset Inventory Prioritization means you must rank IT and OT assets by how essential they are to delivering the in-scope operational function, then use that ranking to drive protection, monitoring, funding, and response focus. Under C2M2 v2.1 ASSET-1.C, exam-ready implementation is a repeatable prioritization method tied to your asset inventory and embedded into planning and budgeting decisions. ¹

Key takeaways:

• Prioritization is a decision system: define criteria, score assets, and assign tiers that drive downstream controls.
• Your highest-priority OT and IT assets must be obvious from evidence: inventory fields, scoring records, and governance approvals.
• Build it into change, procurement, and budget workflows so priorities determine what gets secured first and what gets funded. ²

Compliance teams often have an “asset inventory” but cannot show which systems matter most to delivering the function regulators and customers care about. C2M2’s requirement is narrower and more operational: it expects prioritization of IT and OT assets based on their importance to delivery of the function, within a defined scope. ¹

For a CCO, GRC lead, or Compliance Officer, the fastest path is to treat this as a governance-and-data requirement, not a tooling project. You need (1) a documented prioritization method, (2) an inventory that stores the priority tier and why it was assigned, (3) approvals and exceptions, and (4) proof that the tier actually changes decisions (patching urgency, monitoring coverage, backup rigor, segmentation, incident response playbooks, and funding). ³

This page gives requirement-level implementation guidance you can hand to IT/OT owners, cybersecurity, and finance. It focuses on audit-ready artifacts and practical steps that work even when discovery tooling is imperfect, asset ownership is messy, and OT downtime constraints limit remediation options.

Regulatory text

C2M2 v2.1 ASSET-1.C (MIL1) excerpt: “IT and OT assets are prioritized based on their importance to the delivery of the function.” ¹

What the operator must do

You must be able to show, for the C2M2 assessment scope, that:

1. You have a way to determine “importance to the delivery of the function.” This means defined criteria (mission/business impact, safety, operations, regulatory, and recovery constraints) that apply to both IT and OT. ¹
2. You apply the criteria to assets in your inventory. Each in-scope asset gets a priority tier (or equivalent label) and a rationale that can be reviewed. ¹
3. The priority affects actions and resourcing. Your plans and budgets reflect the prioritization so high-priority assets receive earlier or stronger safeguards and attention. ²

Plain-English interpretation

Asset Inventory Prioritization answers two exam questions: “Which assets matter most?” and “How do you know?” The requirement is satisfied when your inventory clearly identifies critical IT and OT assets, and the organization can demonstrate that cybersecurity work is sequenced and funded according to that criticality within the defined function scope. ¹

Who it applies to

Entity applicability

• Energy sector organizations and critical infrastructure operators using C2M2 to assess cybersecurity maturity for a defined function or environment. ¹

Operational context (what auditors/examiners will scope)

• A defined function scope (for example: generation operations, transmission control, distribution operations, market operations, or a supporting corporate function that directly impacts operations). Your prioritization must be meaningful inside that scope. ¹
• Both IT and OT assets in scope, including supporting services that can be single points of failure (identity, time sync, remote access, backups, engineering workstations, historians, jump hosts). ¹

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

Step 1: Define scope and “function delivery” dependencies

• Write a one-page scope statement: function, sites, networks, and major systems included.
• Identify operational “thin ice” dependencies: systems where failure stops or degrades the function (operations leadership should sign off).
  Artifact: Scope statement + dependency notes approved by operations. ³

Step 2: Establish prioritization criteria (simple and repeatable)

Create criteria that work for IT and OT and can be answered from available data. A practical set:

• Operational impact: loss of availability affects delivery of the function.
• Safety/environmental impact: failure could create unsafe conditions.
• Cyber impact: compromise provides privileged access, lateral movement, or control capability.
• Recovery constraints: restore time is long due to vendor constraints, downtime windows, or rebuild complexity.
• External obligations: contractual/regulatory commitments tied to the function scope.

Keep criteria definitions tight (one paragraph each) and define what “high/medium/low” means in your organization.
Artifact: Prioritization standard (procedure) with criteria and definitions. ¹

Step 3: Choose a tiering model and document the method

Pick a small number of tiers your teams will actually use (examples: “Tier 1/2/3” or “Critical/Important/Standard”). Then document:

• Who assigns tiers (asset owner + security/OT security)
• Who approves (operations leader for OT; IT service owner for IT)
• When tiers must be reviewed (trigger-based reviews work well: new asset, major change, new connectivity, incident)
• How exceptions work

Artifact: RACI + workflow diagram (even a single page is fine). ²

Step 4: Apply tiers to the inventory (minimum viable fields)

Update your inventory schema to include:

• Priority tier
• Rationale (free text, but structured prompts help)
• Owner
• Function/system mapping (which business/operational process it supports)
• Last review date and approver

If you have separate IT CMDB and OT inventory, do not wait for a unified tool. Enforce consistent fields and tier definitions across both.
Artifact: Inventory export showing priority tier coverage across in-scope assets. ¹

Step 5: Make prioritization operational (tie it to control outcomes)

Auditors look for proof that prioritization changes what happens next. Build explicit “tier-to-control” expectations, such as:

• Patching and vulnerability response: higher tier gets faster triage and compensating controls when patching is constrained.
• Monitoring/logging: higher tier has required telemetry and alerting coverage.
• Backup/restore: higher tier has tested restoration steps aligned to recovery constraints.
• Access control: higher tier has stricter remote access patterns and administrative controls.
• Incident response: higher tier has asset-specific playbooks and escalation contacts.

You do not need to promise identical control strength everywhere. You must show deliberate differences justified by tiering and risk acceptance where gaps remain.
Artifact: Tier-to-control mapping matrix + samples of tickets/changes showing tier used to set priority. ³

Step 6: Embed into planning and budgeting (a common failure point)

C2M2 operators routinely score assets but fail to prove resourcing. Build two gates:

• Annual/quarterly security roadmap gate: initiatives must state which priority tiers they protect and why.
• Budget approval gate: funding requests reference asset tiers and planned coverage (monitoring, segmentation, backups, OT hardening).

Retain the records that show decisions were made with the prioritization in view, including deferred work and accepted risk. ¹

Step 7: Run governance and keep it current

• Hold a recurring review with IT, OT operations, engineering, and security to approve tier changes and exceptions.
• Track “unknown owner” and “unassigned tier” as remediation items until closed.

Artifact: Meeting minutes, approvals, exception log, and evidence of remediation for inventory gaps. ²

Required evidence and artifacts to retain (audit-ready)

Maintain a single evidence folder for the scoped function with:

• Prioritization procedure/standard and tier definitions. ¹
• Scope statement and function dependency mapping. ³
• Inventory exports (IT and OT) with priority tier, owner, rationale, and last review.
• Tier assignment/approval records (tickets, meeting minutes, sign-offs).
• Exception register (what is out of standard, why, compensating controls, approver, review trigger).
• Tier-to-control mapping matrix (what additional protections/monitoring apply by tier).
• Planning and budgeting artifacts: roadmap proposals, funding requests, approval notes, and deferral/acceptance decisions. ¹

Common exam/audit questions and hangups

• “Show me your top-tier assets and explain why they are top-tier.” Expect follow-ups on OT systems and shared services.
• “Who approved this tiering and when was it last reviewed?” Missing approvers is a frequent hangup.
• “Where does the priority tier show up in your operational workflows?” If the tier never appears in tickets, change requests, or monitoring coverage decisions, the program looks non-operational.
• “How do you handle assets you cannot patch or monitor?” Auditors want compensating controls and risk acceptance, not promises. ²

Frequent implementation mistakes (and how to avoid them)

1. Treating tiering as a one-time spreadsheet exercise. Fix: require tier fields in the system of record and add a change trigger for review.
2. Prioritizing only OT “crown jewels” and ignoring IT dependencies. Fix: explicitly tier identity, remote access, virtualization, backup, and logging platforms that support OT.
3. No consistent criteria; everything becomes “critical.” Fix: define what makes something top tier and cap top-tier assignment with an operations approval gate.
4. No evidence that prioritization drives spend. Fix: embed tier references in roadmap/budget templates and retain approval artifacts. ¹

Enforcement context and risk implications

No public enforcement cases were provided in the available source catalog for this requirement. Practically, the risk is program credibility: if you cannot explain which assets matter most and show prioritized protection and resourcing, assessors and customer diligence teams will view cybersecurity coverage as ad hoc, especially in mixed IT/OT environments. ³

Practical 30/60/90-day execution plan

Exact timing depends on scope size and inventory maturity, but this phased plan is designed to produce evidence quickly and then harden operations. ²

First 30 days (stand up the method and evidence trail)

• Confirm scope and define “function delivery” dependencies with operations sign-off.
• Publish prioritization criteria and tier definitions.
• Add priority tier fields to the inventory (or establish a controlled interim register) and assign owners for the highest-impact assets first.
• Create an exception register and approval workflow.

Days 31–60 (apply tiers broadly and connect to controls)

• Complete tier assignments for in-scope IT and OT assets, with approvals.
• Build the tier-to-control mapping matrix and align it to existing processes (patching, monitoring, backups, remote access).
• Update templates: change request forms, risk acceptance, and security roadmap intake to include asset tier.

Days 61–90 (embed into planning and budgeting; make it durable)

• Run a governance review cycle; resolve “unknown tier/unknown owner” items.
• Demonstrate prioritization in action with samples: ticket prioritization, monitoring onboarding, backup testing, segmentation plan, or compensating controls for constrained OT.
• Capture budget and planning decisions that reference tiers, including deferrals and approved exceptions. ¹

Ongoing operations (what to keep running)

• Trigger-based reviews for new assets, connectivity changes, and post-incident reassessments.
• Periodic governance reviews and continuous cleanup of inventory completeness issues. ³

Tooling and workflow note (where Daydream fits)

If your bottleneck is evidence assembly and cross-team follow-through, Daydream can act as the control cockpit: map prioritized assets to required safeguards, track exceptions and approvals, and keep the planning/budget artifacts tied to the requirement so audits do not become a scramble. Keep the source-of-truth inventory where it belongs (CMDB/OT inventory), then use Daydream to manage governance and evidence. ²

Frequently Asked Questions

Do we need a single unified inventory tool for IT and OT to meet the requirement?

No. You need consistent prioritization criteria and an inventory record that shows priority tier and rationale for both IT and OT in the scoped function. A unified tool helps later, but assessors mainly test whether the prioritization exists and drives decisions. ¹

How do we prioritize assets when OT patching and scanning are constrained?

Tiering should account for recovery constraints and operational downtime limits, then drive compensating controls and documented exceptions. Keep the exception approvals and the alternative safeguards tied to the tier. ²

What’s the minimum evidence set to satisfy an assessor quickly?

A written prioritization procedure, an inventory export with priority tiers and owners, and approval/exception records for the highest-priority assets usually clear the first hurdle. Add a tier-to-control mapping to show the prioritization changes actions. ¹

Who should approve asset priority tiers in practice?

Asset owners propose tiers, but approvals should come from the accountable operational leader for OT and the accountable service owner for IT, with security providing review. Auditors look for a clear approver and a repeatable workflow. ³

How do we show prioritization impacts budgeting without overhauling finance processes?

Add one field to roadmap and funding request templates that lists the tiers protected and the assets impacted, then retain the approval notes and deferral decisions. This creates a traceable link between tiering and resourcing. ¹

What if we discover assets with no owner or unclear function mapping?

Treat “unknown owner” and “unknown function mapping” as compliance findings, assign interim accountability, and track remediation to closure. Keep the logs that show the cleanup effort and the final assignments. ²

Footnotes

1. Cybersecurity Capability Maturity Model v2.1

2. DOE C2M2 program

3. DOE C2M2 Program (U.S. DOE CESER)