Symantec has revealed the Stuxnet computer virus is the first-known virus specifically designed to target power stations and other real-world infrastructure.
The security company has disclosed how waves of new variants of the virus, which came to light in 2010, were launched at Iranian industrial facilities.
A new research by the security company said some versions of the virus started attacks on their targets within 12 hours of being written.
The research shows that the worm targeted five "industrial processing" organisations in Iran. However, Symantec declined to name the five organisations.
Symantec security operations manager Orla Cox told BBC News that these were the seeds of all other infections caused by the sophisticated malware.
Researchers could identify the targets and track the spread of the virus because Stuxnet collected detailed information about each computer it infected.
Cox said the five organisations were targeted repeatedly between June 2009 and April 2010, adding that one organisation was attacked three times, another was targeted twice.
There were at least three different variants of the worm in these waves of attacks and a fourth one is suspected.
Cox also added, "We see threads to contractors used by these companies. We can see links between them."
The worm first came into light late last year after studies showed a likelihood of a "nation state" to be behind the sophisticated malware written by to target Iran’s nuclear programme.
Though Iran’s uranium enrichment programme is known to have been delayed, Iranian officials have denied that the virus caused any major delays to its nuclear power programme. However, they have admitted that the worm infected staff computers.
The origin of the worm is still unknown.
Cox said Symantec is trying to do epidemiology on the virus and they are trying to understand how and why it spread.
