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Operational technology (OT) cyber resilience means keeping essential processes safe and reliable through disruption—and restoring them in a deliberate order when they cannot continue. That takes more than securing devices: operators need to know which processes matter, how systems and people depend on one another, when connections should be isolated, and how to continue or recover when normal controls are unavailable.
Start with the service, not the device
Define the essential service or production process first. Operations, engineering, safety, and security teams should agree what safe operation requires, what level of degraded capacity is acceptable, and what loss of control or interruption the process can tolerate. Those are operational decisions, not values that a cyber team can set from an IT asset list alone.
Then map the technology, people, communications, vendors, and supporting services that enable the process. Include dependencies that may sit outside the OT network: for example, business systems or external connectivity on which operators rely. A disruption to one dependency can affect several processes, while a device that appears important in isolation may have a workable substitute.
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Build an inventory that supports decisions
An OT inventory is useful when it helps people understand what assets do and what could happen if they are unavailable or compromised. CISA and government partners’ 2025 guide, Foundations for OT Cybersecurity: Asset Inventory Guidance for Owners and Operators, recommends an organized inventory and a taxonomy that classifies assets by function and criticality.
Record more than asset names
Maintain a current record of OT systems, hardware, and software, with enough context to support the work it informs. Depending on the organization, that context can include each asset’s process function, criticality, dependencies, ownership or operational contact, and relationship to other systems. The guide’s sector examples are conceptual aids, not a universal taxonomy that every site should adopt unchanged.
Use the inventory across the asset lifecycle
Connect inventory maintenance to cybersecurity risk management, maintenance and reliability, vulnerability management, incident response, and lifecycle planning. A list that is not updated when equipment or connections change can mislead both routine decisions and incident responders. Make responsibility for updates clear, including how changes made during maintenance, procurement, or engineering work are reflected.
Use function and criticality to set attention and restoration priorities. An asset’s priority should reflect the process it supports, the consequences of losing it, and its dependencies—not simply its technical prominence or ease of finding in a network scan.
Make OT risk a cross-functional decision
Changes to architecture, connectivity, procurement, remote access, and maintenance can alter both cyber exposure and how safely a process can operate. Review these changes with security, engineering, operations, and safety stakeholders before treating them as routine IT choices. The relevant question is not only whether a control reduces a threat, but also whether it can be deployed and maintained without creating unacceptable production or safety risks.
For each significant decision, document the operational outcome being protected, the dependencies affected, the risk introduced or reduced, and who accepts the remaining risk. This gives the organization a basis to revisit the decision when the process, threat conditions, or supporting technology changes. The joint OT principles guide is intended to help organizations identify risks that business decisions may create for OT cybersecurity and continuity; it does not supply a universal scoring formula.
Prepare to isolate connections and keep operating
Decide in advance under what conditions IT/OT connections should be isolated, who has authority to initiate isolation, and how operators will know what to do next. Isolation can limit the spread or impact of a compromise, but the right action depends on the process and its dependencies. A connection that supports safe operation or visibility cannot be treated as disposable without understanding the consequences.
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Define operating alternatives
For each critical process, identify whether it can continue at necessary capacity if IT is compromised, and what workarounds or manual controls are available. Specify the conditions under which each alternative is safe, the people authorized and trained to use it, and the point at which operation should stop rather than continue in an unsafe state.
CISA’s resilience guidance recommends identifying critical processes, developing and regularly testing workarounds or manual controls, and planning how to operate if access to or control of IT and/or OT is lost. The guidance does not prescribe one architecture or a universal manual-operation method; engineering and safety constraints make these choices site- and process-specific.
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Test the transition, not just the written procedure
Exercise how the organization moves from normal operation to isolation or degraded operation, including how teams communicate, what status information remains available, and how they decide whether conditions are safe. A workaround that exists only on paper may fail when staff, communications, or the supporting system it depends on are unavailable.
Make response and recovery executable
Maintain and exercise cyber incident response, resilience, and continuity plans. Assign clear roles, contacts, reporting processes, and coverage so that a disruption does not leave critical decisions waiting on an unavailable person or system. Include the people who operate the process, not only the teams that manage security tools.
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Protect recovery data and procedures
Keep backups isolated from the systems they are meant to restore, and test the backup and restoration procedures. Recovery planning should identify what must be restored first to support safe service, what dependencies need to be available, and how the organization will verify that restored systems are trustworthy and ready for operation.
Plan explicitly for lost access or control
Include scenarios in which teams lose access to IT, OT, or both. Clarify how operators maintain safety, how incident responders coordinate with engineering and operations, and who can authorize reconnection or return to normal control. CISA’s ICS Recommended Practices collection includes resources on incident response capability, defense in depth, patch management, and remote access that can support this planning.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Judge resilience by operational evidence
There is no universal resilience score or single control that establishes readiness. Review proposed controls and plans against the operational questions that matter:
- Safety and service: What is the impact if the process or control is unavailable, and what conditions make continued operation unsafe?
- Function and dependency: Which assets, IT services, vendors, communications links, and people does the process rely on?
- Practical deployment: Can the proposed control be installed and maintained without unacceptable production or safety risk?
- Continuity and restoration: Can the organization isolate affected connections, continue manually or in a degraded mode where safe, and restore service in a justified order?
- Evidence of readiness: Have the workaround, response plan, and backup procedures been exercised or tested?
These questions synthesize factors in CISA and partner guidance on asset inventory, OT cybersecurity principles, and resilience. They are a decision aid, not a prescribed cross-sector rating system.
Official guidance behind the approach
CISA’s Resilience Services page reproduces the National Security Memorandum-22 definition of resilience: “Resilience is the ability to prepare for threats and hazards, adapt to changing conditions, and withstand and recover rapidly from adverse conditions and disruptions.” The definition captures why resilience is an operating capability: preparation, adaptation, continuity, and recovery all depend on coordinated decisions before an incident.
For OT-specific practices, CISA’s ICS Recommended Practices collection brings together resources on topics including incident response, defense in depth, patch management, and remote access. These materials complement the joint OT principles, the 2025 asset-inventory guidance, and CISA’s resilience advice; apply them in the context of the actual process and its safety requirements.
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