IT systems have a well-established playbook for detecting and remediating threats. An employee’s compromised laptop can be isolated from the network and function within hours with a strategic and well-timed software patch. However, cybersecurity best practices that work for IT don’t apply quite as neatly to cyber-physical systems (CPS) environments.
Cyber-physical systems connect digital technology with the physical world. They include industrial control systems in manufacturing plants and electrical substations, as well as connected medical devices used in patient care. A security incident in these environments can interrupt essential services, damage equipment, or put people at risk.
Especially given the growing volume of IoT connections — the global IoT market will reach 40.8 billion connections by 2030 according to GSMA Intelligence — enterprises need a more strategic, shift-left approach to CPS cybersecurity. Security teams must adopt strategies specially designed for cyber-physical systems as they walk a fine line between continuous availability and security. They need a combination of passive visibility, operational context, risk-based mitigation and coordinated response.
Why cyber-physical systems operate under different rules
Many IT endpoints can be isolated, patched, or rebuilt with limited disruption to the wider business. In operational environments, the same intervention may interrupt a process that must run continuously. A change to one device can affect equipment and services far beyond that device.
“Taking a controller offline to address a vulnerability can bring an entire production line to a standstill, potentially costing the business thousands in lost output. In OT environments, security teams have to reduce cyber risk while keeping critical operations running,” says Tarannum Parkar, Product Marketing, OT Security, at ServiceNow.
An operational technology (OT) programmable logic controller is very different from a laptop or a server in the IT space and is not built for today’s cybersecurity methods. “Many of these devices run legacy or specialized software, communicate through specialized protocols, and operate within environments where maintenance windows are limited,” says Tarannum Parkar, Product Marketing, OT Security, at ServiceNow. Legacy OT systems have limited resources like memory and CPU, so aggressive cybersecurity scans can destabilize these devices. And because many of these OT components are mission-critical, they cannot simply be isolated from processes without a plan to keep operations running.
How to gain asset visibility without disruption
The first step in CPS security is to build a comprehensive inventory of assets. “Asset visibility is an essential first step because there are a lot of unknown and unmanaged assets out there,” Parkar says.
A useful inventory goes beyond device counts and IP addresses. Teams need information such as device type, software and firmware versions, location, and communications. They also need to know which process an asset supports, who is responsible for it, and what could happen if it becomes unavailable or is compromised.
Many CPS assets cannot support endpoint agents, and aggressive scanning can disrupt sensitive equipment. Discovery methods must account for the device and its operational requirements.
Passive monitoring analyzes existing network traffic to help identify assets and map their communications without actively querying sensitive devices. Observing those communications over time helps establish a baseline of expected behavior and identify suspicious changes.
Prioritize vulnerabilities by operational risk
Improving asset visibility is an essential first step, but security teams cannot afford to attend to all vulnerabilities at once. Instead, they need to prioritize exposures according to the criticality of the asset’s functions and operational context.
Vulnerability prioritization should combine technical severity with the likelihood of exploitation and the potential impact on operations. Teams need to assess whether attackers are actively exploiting a vulnerability, whether the affected asset is reachable, and whether existing controls limit its exposure. That assessment must also consider the process the asset supports and the consequences of a compromise for safety, production, or essential services. For example, a lower-severity vulnerability on an exposed controller supporting a critical process may warrant attention before a higher-severity finding on a well-protected, less critical asset.
Reduce cyber risk while maintaining operations
Addressing CPS vulnerabilities requires a response that accounts for operational constraints. When patching must wait, urgent risks still require action through compensating controls that reduce exposure while preserving operations.
Segmentation can restrict unnecessary communications, while access controls can limit who can reach sensitive assets. Both require an understanding of operational needs so that protection does not interrupt essential activity. These techniques, along with a constantly updated asset inventory, are key to good cybersecurity hygiene.
Asset and risk intelligence must also reach the people responsible for taking action. Clear ownership and coordinated workflows help security and operations teams approve changes, schedule interventions, and verify that the response has reduced exposure. A continuously updated understanding of assets and their operational dependencies provides the foundation for these decisions. It enables organizations to control access, prioritize exposures, and coordinate remediation while protecting safety and continuity.
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