What is the difference between ISA 99 and 62443?

In the field of industrial cybersecurity, there are several standards that companies and organizations rely on to protect their critical infrastructure. Two of these standards are ISA 99 and IEC 62443. While both address the same concern of securing industrial control systems (ICS), they have some key differences in scope and approach.

Scope

ISA 99, also known as the International Society of Automation standard, focuses on the entire industrial automation and control system (IACS). It includes principles, terminology, and models for implementing security measures across the entire lifecycle of an IACS. This involves identifying and assessing risks, designing secure solutions, implementing controls, and continuously monitoring and improving security.

IEC 62443, on the other hand, has a narrower scope. It specifically targets operational technology (OT) cybersecurity for industrial automation and control systems. It provides a systematic framework for managing cybersecurity risks within the OT environment. The standard defines requirements and best practices for each stage of the system's life cycle, including development, implementation, operation, and decommissioning.

Approach

ISA 99 takes a broader, more holistic approach to industrial cybersecurity. It emphasizes a multi-layered defense strategy that combines technical, procedural, and organizational measures. The standard promotes the concept of defense-in-depth, which involves implementing multiple layers of security controls at various levels of the IACS architecture. This approach acknowledges that no single security measure can provide complete protection, and a combination of different controls is necessary to reduce risk.

IEC 62443, on the other hand, adopts a risk-based approach. It emphasizes the importance of identifying and assessing risks specific to the IACS and tailoring security measures accordingly. The standard encourages organizations to conduct risk assessments to identify potential vulnerabilities, threats, and impacts on the OT infrastructure. Based on these assessments, appropriate security controls can be selected and implemented.

Compatibility

While there are differences between ISA 99 and IEC 62443, it's important to note that they are not mutually exclusive. In fact, they can complement each other. Many organizations use ISA 99 as a guiding framework for implementing security measures across their entire IACS, while adopting IEC 62443 as a specific standard for managing cybersecurity risks within their industrial control systems.

It is also worth mentioning that both standards have gone through several revisions and updates over time to keep pace with evolving cyber threats and technological advancements. Organizations should stay updated with the latest versions of these standards and ensure compliance with the recommended practices for effective industrial cybersecurity.

In conclusion, ISA 99 and IEC 62443 are two important standards in the field of industrial cybersecurity. While ISA 99 provides a comprehensive framework for securing industrial automation and control systems, IEC 62443 specifically focuses on OT cybersecurity. By understanding the scope and approach of these standards, organizations can implement the necessary security measures to protect their critical infrastructure from cyber threats.