Targeting the infrastructure of industrial units, Stuxnet was the first discovered worm that destroyed power stations.

Later, a series of nuclear viruses infected five Iranian industrial facilities and some of the destruction caused was completed, in less than 12 hours of being launched.

"We are trying to do some epidemiology. We are trying to understand how and why it spread,” said Orla Cox of security company Symantec.

Virus could lead to a nuclear accident

The researchers at Symantec found that the attacks had started by June 2009, much earlier than the independent internet security experts raised an alarm about the attacks.

Symantec traced attacks on five industrial sites
A post on the company’s blog stated that its researchers were able to find out about the attacks on Iranian industrial facilities, after analyzing the malware comprehensively.