ISA/IEC 62443 Lead Implementer key terms

A collection of personnel, hardware, software, and policies that can affect or influence the safe, secure, and reliable operation of an industrial process. It includes control systems such as DCS, PLC, SCADA, and safety instrumented systems.

The system that responds to input signals from the process and its associated equipment and generates output signals causing the process to operate in the desired manner. It performs regulatory and discrete control but not safety functions.

A system composed of sensors, logic solvers, and final control elements designed to bring an industrial process to a safe state when predetermined conditions are violated. It is engineered for high reliability and independence from the BPCS.

Supervisory Control and Data Acquisition: a system architecture that gathers data from remote field devices and issues supervisory commands, typically used across geographically distributed assets such as pipelines, substations, and water networks.

A ruggedized industrial computer that executes ladder logic or other control programs to operate machinery and processes in real time. It interfaces with sensors and actuators and is often networked to higher-level systems.

A field device deployed at a remote site that collects data from sensors and transmits it to a master station, and executes commands received in return. It often includes local control and communication buffering.

A discrete level, defined by IEC 61508 and referenced in IEC 62443, expressing the required reduction of risk achieved by a safety function. It is not the same as the ISA/IEC 62443 Security Level.

An ISA/IEC 62443 measure of the security strength of a system or component against a defined threat. Target SLs are set per zone and conduit, while capability SLs describe what a product can achieve.

The security level that a zone or conduit must achieve to satisfy the results of a risk assessment. It is chosen by the asset owner and drives the selection of countermeasures and product capability requirements.

The security level actually realized by a zone or conduit after countermeasures are implemented and verified. It may be lower than the target if gaps remain, requiring additional mitigation or compensating controls.

A modeling approach in which assets are grouped into zones of similar security requirements, and conduits define the controlled communication paths between zones. This supports segmentation and limits the blast radius of an incident.

A layered security strategy in which multiple independent countermeasures are deployed so that failure of one layer does not compromise the whole system. In IACS it combines network, host, application, and physical controls.

The practice of dividing a network into isolated subnets, often enforced by firewalls or data diodes, to restrict traffic flows. In IACS it prevents lateral movement from enterprise IT into control networks and between process areas.

A buffer network segment placed between the enterprise IT network and the IACS network. It hosts shared services such as historians, patch repositories, and jump hosts, and brokers all traffic between the two environments.

A reference architecture that organizes industrial networks into hierarchical levels, from physical process at Level 0 up through enterprise systems at Level 4 and beyond. It is used to reason about segmentation and trusted boundaries.

The property that a system is accessible and operational when required. In IACS it is often the highest-priority security objective, because loss of control can threaten safety, the environment, and production.

The security objectives of confidentiality, integrity, and availability. In industrial environments the priority order is typically inverted relative to IT, with availability and integrity ranking above confidentiality due to safety and uptime consequences.

The ability of a system to anticipate, absorb, adapt to, and recover from adverse conditions while maintaining required operations. In IACS it includes redundancy, fail-safe design, and tested recovery procedures.

The capability of an organization to continue delivering products or services at acceptable predefined levels after a disruptive incident. For IACS it links cyber incident response to production and safety recovery planning.

The extension of networked sensing and computing into industrial operations, connecting devices and analytics to control environments. It expands the attack surface and complicates asset inventory and patching.

A family of standards addressing security for industrial automation and control systems. It is organized into general, policy and procedure, system, and component categories and covers both asset owners and product suppliers.

The organization responsible for operating and maintaining an IACS and accountable for its security posture. In ISA/IEC 62443 this role performs risk assessment, defines target security levels, and verifies achieved levels.

A structured process of identifying threats and vulnerabilities, estimating likelihood and consequence, and determining risk levels for IACS assets. Its results drive zone partitioning and target security level selection.

The set of policies, processes, roles, and responsibilities an organization uses to govern IACS security. ISA/IEC 62443-2-1 specifies requirements for establishing and maintaining it across the system lifecycle.

A structured framework, described in ISA/IEC 62443-2-1 and 62443-4-1, that rates how completely and consistently security processes are performed. It progresses from initial/ad hoc practices toward continuously improving, optimized practices.

The overall organizational effort to protect IACS, encompassing governance, risk management, architecture, operations, and incident response. It is implemented through a CSMS and assessed against maturity levels.

The seven high-level security objectives in ISA/IEC 62443: identification and authentication control, use control, system integrity, data confidentiality, restricted data flow, timely response to events, and resource availability.

A specific, testable requirement derived from a foundational requirement and applied to a system under consideration. SRs are numbered and tied to security levels, forming the basis for verification activities.

A requirement in ISA/IEC 62443-4-2 that applies to individual products or components, such as embedded devices or host software. Suppliers demonstrate compliance through capability security levels.

An additional, stricter requirement attached to a base system requirement that raises its security strength. REs distinguish what is needed to reach higher security levels within the same foundational requirement.

A process, required by ISA/IEC 62443-4-1, for building security into products from concept through maintenance. It includes threat modeling, secure coding, verification, defect management, and patch handling.

The controlled process of identifying, testing, approving, deploying, and tracking software updates. In IACS it must be balanced against uptime and validation requirements, often using staged or compensating approaches.

Documented procedures for detecting, containing, eradicating, and recovering from security incidents, including roles, communications, and escalation paths. For IACS it must account for safety and process continuity.

An alternative control applied when a required security measure cannot be implemented directly, such as on legacy equipment. It must provide equivalent risk reduction and be documented and monitored.

The activity of confirming that implemented countermeasures actually achieve the target security level for a zone or conduit. It uses assessment, testing, and evidence review rather than relying on design intent alone.

Systems and assets, whether physical or virtual, so vital that their incapacity or destruction would have a debilitating impact on security, economic security, public health or safety. IACS frequently underpin such infrastructure.

An approach in which security requirements are built into systems from the earliest design stages rather than added later. In ISA/IEC 62443 it is reflected in zone design, product SDL requirements, and lifecycle planning.