Glossary

A vendor or agency publication describing affected products, impact and recommended mitigations.

The idea of complete physical isolation. In practice it degrades through media, laptops and vendor connectivity, and should not be relied on as a sole control.

Basic Process Control System

The control system performing normal process regulation, as distinct from the safety system.

Common Industrial Protocol

An object-oriented application layer used by EtherNet/IP, DeviceNet and ControlNet.

An alternative control applied when the primary remediation (usually patching) is not feasible.

A defined, controlled communication path between zones, carrying only approved flows.

Cyber-Physical System

A system in which computation and networking are tightly integrated with physical processes — a broader term that includes OT, IIoT and connected medical or building systems.

Common Vulnerabilities and Exposures

A unique identifier assigned to a publicly disclosed vulnerability.

Common Vulnerability Scoring System

A severity score describing technical characteristics of a vulnerability. It does not describe your environmental consequence on its own.

Common Weakness Enumeration

A classification of software and hardware weakness types underlying vulnerabilities.

Distributed Control System

An integrated control platform for continuous processes within a single plant, with tightly coupled controllers, operator stations and engineering tools.

Layering independent controls so that the failure of one does not expose the process.

A telemetry protocol used widely in electric and water utilities, with optional Secure Authentication.

Exploit Prediction Scoring System

A model estimating the probability that a vulnerability will be exploited in the near term.

Engineering Workstation

The computer holding engineering software and controller projects — the legitimate path to change control logic.

A digital communication network connecting field devices to controllers, such as PROFIBUS or FOUNDATION Fieldbus.

IEC 61850 Layer 2 multicast messaging carrying time-critical protection signals between substation devices.

A time-series database storing process values, events and alarms for analysis and reporting.

Human-Machine Interface

The operator's interface to the process, displaying values and alarms and providing control actions.

Industrial Control System

The collective term for control systems used in industrial production, including SCADA, DCS and PLC-based systems.

Industrial DMZ

A buffer network between enterprise and control environments where all cross-boundary flows terminate.

Intelligent Electronic Device

A microprocessor-based substation device performing protection, control, metering or monitoring.

Industrial Internet of Things

Connected industrial devices and gateways delivering data to enterprise or cloud platforms, often outside traditional control architectures.

A hardened intermediate system that all interactive access into a protected zone must traverse.

Known Exploited Vulnerabilities

CISA's catalog of vulnerabilities with reliable evidence of exploitation in the wild. Evidence of exploitation, not a measure of prevalence.

The practice of baselining expected assets, peers, protocols and timings so that abnormal behaviour becomes visible.

A condition where operators can no longer influence the process as intended.

A condition where operators can no longer observe the process accurately.

A scheduled period in which changes can be made with reduced operational impact.

A condition where the information presented to operators has been falsified.

Running the process using local controls and human procedures when automated systems are unavailable or untrusted.

Manufacturing Message Specification

A client/server messaging standard used as the IEC 61850 station-bus profile on TCP port 102.

Management of Change

The formal engineering process governing modifications to process equipment, control logic and safety functions.

A widely used industrial protocol for reading and writing device registers, available in serial (RTU) and TCP variants.

A family of interoperability standards for industrial data exchange; OPC UA is the modern, secure-capable successor to OPC Classic.

Operational Technology

Hardware and software that detects or causes change by directly monitoring and controlling physical devices and processes.

Programmable Automation Controller

A controller combining PLC determinism with richer computing, networking and data-handling capability.

Observing network traffic without transmitting, avoiding the operational risk of active probing in production OT.

Programmable Logic Controller

A ruggedised industrial computer executing deterministic control logic against field I/O.

A reference model organising industrial systems into levels from physical process (Level 0) to enterprise (Levels 4–5), commonly extended with an industrial DMZ at Level 3.5.

Remote Terminal Unit

A field controller at a remote site that collects telemetry and executes commands from a master station.

Supervisory Control and Data Acquisition

A supervisory architecture for monitoring and controlling geographically distributed assets from a central location.

Safety Instrumented Function

A specific protective function implemented by a safety instrumented system with a defined safety integrity requirement.

Safety Integrity Level

A measure of the risk-reduction performance required of a safety instrumented function.

Safety Instrumented System

An independent protection layer that brings the process to a safe state when defined conditions are exceeded.

Switched Port Analyzer

A switch feature mirroring traffic to a monitoring port; convenient but can drop frames under load.

A specification defining MQTT topic structure and state management for industrial applications.

Test Access Point

A passive hardware device that copies network traffic to a monitoring system without affecting the link.

A device such as a laptop or test set that moves between environments and can carry risk across boundaries.

A planned, extended shutdown for major maintenance — often the only realistic window for significant OT changes.

A grouping of assets with common security requirements, as defined in IEC 62443.