Those products that are deployed within a CS environment typically focus on monitoring the same types of information monitored within the corporate and supervisory networks -- namely system authentication and access logs.
Unfortunately, many miss the wealth of data made available to them by the process historian, the system employed for the storage of PI data, which is used to facilitate trending and analytical auditing for CS-deployed infrastructure. The historian is essentially a log manager for control systems that typically presents itself for business intelligence use. Unfortunately, security (as thought about in the enterprise) is not the primary audit and analytics business case for the collected data: ESIM products could fill this gap.
Although most ESIM products are able to track changes in system behavior, the tiny and frequent adjustments to CS systems to improve operational efficiency could create more noise than signal for the proper isolation of anomalous activity. Vendors will need to work closely with entrenched PI systems providers to better understand the raw data being generated and collaboratively tune their products to efficiently and accurately correlate and alert on the minutia.
As highlighted by the recent Stuxnet infestation in Iran, the monitoring of these sensitive environments is no longer constrained to the operational efficiency of power readings across utilities. System and network anomalies now require a keen security eye to draw the line between a malfunctioning industrial system and rogue software deployed by an adaptive persistent adversary to monitor, or in some cases disrupt, the sensitive systems.
Andrew Hay is senior analyst with The 451 Group's Enterprise Security Practice and is an author of three network security books. Follow him on Twitter: http://twitter.com/andrewsmhay.