September/October 2013

ISA99 standard defines key technical requirements for secure industrial control systems

The ISA-62443 series of standards, being developed by the ISA99 committee and adopted globally by the International Electrotechnical Commission (IEC), is designed to provide a flexible framework to address and mitigate current and future vulnerabilities in industrial automation and control systems (IACS).

A newly published standard in the series, ISA-62443-3-3-2013, Security for Industrial Automation and Control Systems Part 3-3: System Security Requirements and Security Levels, addresses risks arising from the growing use of business information technology (IT) cybersecurity solutions to address IACS cybersecurity in complex and dangerous manufacturing and processing applications.

IACS security goals typically focus on control system availability, plant protection, plant operations, and time-critical system response. IT security goals, in contrast, often focus more on protecting information than physical assets. For this reason, use of IT cybersecurity solutions to address IACS security must be implemented knowledgeably. This prevents unintended vulnerabilities that could lead to potentially disastrous health, safety, environmental, financial, or reputational impacts in deployed control systems.

The new ISA99 standard addresses this concern with an approach to defining system requirements that is based on a combination of functional requirements and risk assessment, and an awareness of operational issues. The standard provides detailed technical control system requirements associated with seven foundational requirements described in the groundbreaking first ISA99 standard, ISA-62443-1-1 (99.01.01), including defining the requirements for control system capability security levels. Those responsible for IACS cybersecurity will use these requirements in developing the appropriate control system target security levels for specific assets.

"This standard provides highly relevant and practical direction to asset owners, system integrators, and suppliers by describing the major system-level technical requirements for a secure IACS," stated ISA99 co-chair Eric C. Cosman of the Dow Chemical Company. "It serves as a cornerstone in the ISA-62443/IEC 62443 series, complementing other standards including ISA-62443-2-1, which addresses the processes and procedures needed for security."

The ISA99 committee drew on the input and knowledge of IACS security experts from across the globe in developing the standard. Unlike programs targeted at a single industry, ISA99 is applicable to all industry sectors and critical infrastructure. It recognizes the interrelated nature of industrial computer networks in which cybervulnerabilities exploited in one sector can affect multiple sectors and infrastructure.

"The new standard represents a collaborative effort of experts from multiple industries around the world," stated the ISA99 task group leader for the project, Jeff Potter of Emerson Process Management. "Our intensive series of revise-and-review cycles has resulted in a rigorously reviewed standard reflecting the best current thinking in control systems security. Our joint work with IEC experts provides users with further assurance that this is a truly global standard that can be used to design, build, operate and regulate with full confidence in its longevity and cross-national applicability."

ANSI/ISA-62443-3-3-2013 was approved as an American National Standard in August 2013. An essentially identical version will be published by the IEC in the near future.

The standard is available at (select "62443" from the drop-down list and scroll down) or by calling +1-919-990-9200.

Ongoing development and collaboration

Several additional standards are currently in active development by ISA99, including:

  • ISA-62443-3-2
    Security Levels for Zones and Conduits
  • ISA-62443-4-1
    Product Development Requirements
  • ISA-TR62443-2-3
    Patch Management in the IACS Environment
  • ISA-62443-1-3
    IACS Security Compliance Metrics
  • ISA-62443-4-2
    Technical Security Requirements for IACS Components

The near-simultaneous adoption of the ISA99 standards by the IEC reflects a long and productive collaboration through which many original ISA standards have been adopted to become widely used IEC global standards in vital areas including industrial cybersecurity, enterprise-control system integration (ISA95), batch process control (ISA88), and process safety (ISA84).

The expertise and input of ISA99 is also evident in the close cooperation with key leaders from the White House National Security Staff on Cybersecurity, U.S. Department of Homeland Security, and U.S. National Institute of Standards and Technology in the ongoing development of a U.S. national cybersecurity framework. The framework is a key element in the executive order signed by President Obama in February 2013, which called for the U.S. government to work closely with key industry partners to protect critical infrastructure.

For more information on ISA99, contact Charley Robinson, ISA Standards, or +1-919-990-9200.