It was a vulnerability in a PLC belonging to Siemens’ Step7 control system that was the target of the sophisticated Stuxnet worm. Stuxnet was discovered on systems in Iran last year and is believed to have been designed by a nation state aimed at destroying uranium-enrichment centrifuges at the Natanz nuclear facility in Iran.

Thanks to Decius trying to educate us environmental engineers, I'm a little closer to understanding how totally fucked Siemens' SCADA is. Thanks, Decius!

-janelane

Fearing Industrial Destruction, Researcher Delays Disclosure of New Siemens SCADA Holes | Threat Level | Wired.com