A large, coal-fired electrical generating-station recently installed control system security software, Verano Industrial Defender system (VID), with seamless installation and operation of the continuously run facility in mind. Based on a Sun Solaris (Unix) platform, major control of the plant is accomplished through a Invensys Foxboro I/A system, with the operator interface provided by Foxboro operator workstations—some with dual screens. There are also engineering workstations and many control processors, all on one I/A control system network, or node bus.

Plant personnel installed the system in early February 2004 for use, observation, and evaluation. In-service time for testing and observation was several months in duration.

The original installation was on a stand-alone plant simulator comprising a Foxboro Node Bus, an Ethernet network and a personal computer (PC) emulating X-window displays.

Most Unix-based DCS/SCADA systems use X-windows protocol—sometimes called X11—to render user graphics on various video display monitors. UNIX applications contact an X-windows server asking that the output be displayed on a particular screen and that input come from a certain mouse and keyboard. Usually the peer-to-peer communication between application and X-windows server is over the network, such as WAN/LAN/Internet. The protection of the communication channel between UNIX applications and the X-windows server is through a limiting host list, which is not very secure. (The protocol has vulnerabilities well known to hackers.) Examples of best-known X-windows emulators are Hummingbird Exceed and Reflections X from attachmateWRQ.

Various tests on the simulator system were performed to illustrate outside logins, telnet session, external computer connections, control processor reboots, and "virus-shell" attacks. (Most computer operating systems support command shells, which provide a user- or application-programming-interface to allow users to write batch programs and scripts. Hackers use command shells to write and run malicious code.) Graphic reports were captured for later use and illustration. Testing on the simulator system lasted for about 2.5 days. VID monitored and detected all tested operations, and simulated attacks on the simulator system.

VID was then installed on a running unit and set to monitor the node bus, including all Foxboro I/A operator workstations and a second "subnet"—an Ethernet network consisting of remote monitoring PCs. VID was installed while the unit was on-line without the need to reboot processors. No degradation of Foxboro I/A control-system performance was experienced after VID installation.

Observation showed the communication between the various workstations over both networks, and the monitoring system provided information on a range of parameters within the workstations.

The application also served as a system administrator tool for monitoring workstation health. VID was used to capture and resolve long-term engineering-workstation performance issues, such as monitoring machine disk-space usage. Overnight it was seen that machine disk use was increasing. Rising disk space was occurring in the partition dedicated for swap space, indicating that the machine had a program running that was "leaking memory." The machine would eventually run out of swap space and lock-up. This long-standing problem had gone undiagnosed for more than a year. Within a day of installing VID, the system pinpointed the problem's root cause and identified the faulty application.

VID satisfied its main purpose: detecting notable items for control system security. It did this on the stand-alone simulator system, including outside logins, and simulated virus attacks. It also performed these functions on the main unit installation, detecting telnet and FTP (file transfer protocol) sessions.

The user interface to VID includes alarming, logging, reporting, and trend functions. Alarming was used for notification of security problems, and, secondarily for system health parameters. It provided notification of circumstances indicating security concerns and items related to system health issues. Logging and report functions gave a chronological view of detected measured issues. Trending graphically depicted the monitored system parameters.

VID performed the stated security functions, providing flexibility to fine-tune to the control system. It also functioned as a system administrator's tool, and helped monitor health.