When distributed control systems (DCS) first appeared on the industrial automation scene in the mid-1970s, the focus was on control and operator interface. While control and human machine interface (HMI) are still im-portant, todays DCSs have evolved to place increased emphasis on integrating plantwide asset and operational information to enable opera-tional excellence. Furthermore, automation suppliers have moved away from the proprietary hardware, software, and communications of the past, incorporating commercial-off-the-shelf (COTS) technologies where practical and appropriate to do so. At the same time, plant engineering and opera-tions groups have adopted many of the same standards already in place at the enterprise IT level, and todays DCSs reflect this.
Todays process control systems can take advantage of advanced general-purpose IT to reduce costs, improve performance, enable interoperability and add other important new capabili-ties. However, the very same technologies make todays industrial systems increasingly vulnerable to security intrusions – malicious or otherwise – from both within and without the plant. Certainly, the IT world has devel-oped powerful tools and techniques to help prevent, identify, and mitigate the effects of intrusions. However, requirements specific to industrial systems (such as the need to maintain nonstop operations and provide deter-ministic response) often make employing these tools and techniques in industrial environments problematic.