Global Cyber Agencies Call for Exhaustive OT Inventories to Combat Threats
Global cybersecurity agencies are urging critical infrastructure operators to build a full picture of their operational technology environments, although analysts caution that mapping every corner of sprawling, decades-old networks may prove harder in practice.
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Guidance backed by the United Kingdom’s National Cyber Security Centre and the U.S. Cybersecurity and Infrastructure Security Agency and other allied partners’ cyber agencies details a principles-based framework for creating and maintaining a “definitive record” of OT environments. It calls on operators of power grids, waters systems and factories to catalogue their assets by criticality, while documenting system connectivity, validating and maintaining records through structured change management and rigorously managing third-party access and contractual risks.
Implementing and maintaining a definitive record of OT environments is feasible and necessary, OT security experts told Information Security Media Group. But the process demands a major shift in how operators approach asset visibility, since legacy systems make real-time inventory difficult. Still, the growing sophistication of cyber-physical threats means organizations can no longer afford to operate without a dynamic record of who is accessing what and when, analysts said.
“Having a source of truth is extremely important for complex legacy environments,” Kevin Greene, chief cybersecurity technologist for the public sector at BeyondTrust. Greene said removing blind spots through a definitive record will allow critical infrastructure operators to better defend mission-critical systems. The push for documentation aligns with broader industry efforts around software bills of material, vulnerability management, asset tracking and zero trust to ensure security decisions are informed by a single, authoritative view.
He added that there is an ongoing “shift and consensus towards prescriptive requirements across the Five Eyes and international partners that points to enhancing visibility across OT environments as non-negotiable.” Those prescriptive requirements will eventually underpin controls like patching, segmentation, identity protection and monitoring to strengthen OT defenses against accelerating cyberattacks, Greene said.
That shift can be seen in the United States in updates to NIST SP 800-82, CISA’s cross-sector OT advisories and recent mandates in energy, transportation and water. Governments are moving in the same direction around the world, pressing operators to keep precise inventories, document configuration changes and log critical events in ways regulators or auditors can validate.
The guidance instructs operators to go beyond static asset lists and build living records that can account for different methods of connectivity, change management and third-party access. It also encourages stakeholders to document network protocols and architectural security controls.
Experts say the real value of a definitive record comes when it is tied to active threat intelligence and risk scoring. By correlating device data with CISA’s Known Exploited Vulnerabilities catalog and tools like the Exploit Prediction Scoring System, operators can turn inventories into dynamic risk management platforms that highlight the most pressing threats, said Sonu Shankar, president and COO at the extended internet of things cybersecurity firm Phosphorus.
“Maintaining a definitive record is not only about identifying assets but also about ensuring the record remains relevant and actionable over time,” said Shankar. “Sustaining such a record demands organizational commitment and integration into change management workflows, but the technical barriers are no longer insurmountable.”
Many critical infrastructure operators struggle with limited resources and staff. Experts say the technology now exists to continuously refresh asset data, validate its accuracy and enrich it with live threat intelligence. For critical sectors especially, the “definitive record” is shifting from aspirational guidance to a practical baseline – one seen as essential for resilience and regulatory readiness.
The guidance acknowledges that a definitive record is a governance issue, requiring collaboration between OT and IT teams, as well as clear accountability for how system knowledge is maintained. By framing the record as a “single source of truth,” the guidance suggests that resilience against future attacks could depend as much on exhaustive documentation and inventory lists as on firewalls, intrusion detection and rapid response efforts.