"Stuxnet is a computer worm discovered in June 2010. It initially spreads via Microsoft Windows, and targets Siemens industrial software and equipment.
While it is not the first time that hackers have targeted industrial systems,it is the first discovered malware that spies on and subverts industrial systems, and the first to include a programmable logic controller (PLC) rootkit.
The worm initially spreads indiscriminately, but includes a highly specialized malware payload that is designed to target only Siemens supervisory control and data acquisition (SCADA) systems that are configured to control and monitor specific industrial processes.
Stuxnet infects PLCs by subverting the Step-7 software application that is used to reprogram these devices."
"It could adjust motors, conveyor belts, pumps. It could stop a factory. With right modifications, it could cause things to explode."