ISA 99/IEC 62443.
In 2002 the International Society of Automation (ISA) began writing a series of standards entitled ISA 99, which address the subject of cybersecurity for industrial automation and control systems. The standards describe the basic concepts and models related to cybersecurity, as well as the elements contained in a cybersecurity management system for use in the industrial automation and control systems environment. They also provide guidance on how to meet the requirements described for each element.
One technical report and three standards have been released so far with the most recent being ANSI/ISA-99.02.01:2009 entitled, "Security for Industrial Automation and Control Systems: Establishing an Industrial Automation and Control Systems Security Program.” This useful document is focused on control system security practices for owners and operators of industrial automation systems.
TC 65 WG 10 of the International Electrotechnical Commission (IEC) has joined with ISA 99 and will publish IEC versions of the standards under IEC 62443. There are currently two documents published in the series. One is IEC 62443-2-4, which is the IEC equivalent of ANSI/ISA-99.02.01:2009. These standards are expected to become the core standards for industrial control security worldwide.