Investigation shows the failure for the shot-down at the Browns Ferry Nuclear Power Plant, U.S. in August 2006, was caused by the control units for water pumps that locked-up following an increased data traffic, called "data storm".

However no worms nor viruses have been found and the most probable cause is a failure in a control unit, programmable logic controller (PLC), that started to transmit large amount of data over the internal network. But until the cause of the increased network load can be explained it can not be excluded that the problems came from an external ”denial-of-service” attack.

- The incident shows it becomes more and more important to have a high computer security level, not only for the standard computers used for administrative tasks, but also for industrial and production environments including PLCs and systems for Supervisory Control and Data Acquisition (SCADA), says Leif Åkesson, CEO at InformAsic.

More about the incident can be found on Security Focus and you can read about security solutions from InformAsic here.