Anonymous, the leaderless 'hacktivist' collective that recently launched DDoS attacks in support of WikiLeaks, claims to have got hold of the Stuxnet worm - and could use it to launch further attacks on targets including Iran's nuclear programme.
Israeli and US secret services are alleged to have created Stuxnet in order to launch the sophisticated cyber attack on Iran.
Anonymous claims it has obtained details of the worm from the emails of security researchers HBGary, after the collective attacked the company's website earlier this month in revenge for the US firm's help for the FBI in identifying alleged members of Anonymous.
As yet, Anonymous has not announced its intention to use the malicious code - but the 'online living consciousness' has signalled its disapproval of the Tehran regime in an open letter to the Iranian people, stating:
"People of Iran, you will not be denied your right to free speech and free press; your right to freedom of assembly, uncensored information and unlimited access to the Internet; your right to a life without oppression and fear."
The group plans to launch attacks in support of the country's pro-democracy 'green movement'.
But security experts have raised doubts over Anonymous's ability to exploit the worm in order to carry out attacks on Iran - in particular with regard to high-profile targets such as the Bushehr nuclear reactor complex, the target of the original attacks last year.
Russian experts working on the reactor recently warned the Kremlin that damage caused by the earlier Stuxnet attack could cause 'another Chernobyl' if Iranian nuclear chiefs press ahead with their existing timetable for bringing the site on-stream.
"It would be possible [for Anonymous to use Stuxnet in an attack]," Orla Cox of security analysts Symantec told the UK's Guardian newspaper. "But it would require a lot of work, it's certainly not trivial.
"The impressive thing about Stuxnet is the knowledge its creators had about their target. So even if you have got access to it you need to understand the target - that requires a lot of research."