- Links turn any PC into an unwitting part of attack
- Part of 'hacktivist' group Anonymous's cyber attacks
- Retaliation for U.S. strike at file-sharing site
Last updated at 3:17 PM on 20th January 2012
Hacker group Anonymous have become a cult hit on Twitter, with 249,000 followers - but security experts Sophos warn that fans, are being tricked into taking part in its attacks.
Links being forwarded via Twitter actually make people's PCs part of Anonymous's 'denial of service' attacks against U.S. government sites and anti-piracy organisations.
The links are being forwarded as part of Anonymous's recent 'Operation Megaupload' - a retaliation for the U.S. government 'taking down' a file-sharing site.
They look like ordinary web links, but launch cyber attacks from whatever PC you access them on.
People who click the links unwittingly become part of Anonymous's attacks - and hit any website that the 'hacktivist' group chooses.
It's a change of tactics for Anonymous - and security experts warn that claiming you clicked on a link by accident may not be a defense.
The attacks, a 'denial of service' attack, rely on thousands of PCs sending information to sites at once to crash them.
'In the past, Anonymous has encouraged supporters to install a program called LOIC, which allows computers to join in an attack on a particular website, blasting it with unwanted traffic,' said Graham Cluley, senior technology consultant at Sophos.
'I'm not sure if participants in this instance would get away with claiming that they innocently clicked on links by mistake,' says Graham Cluley, senior technology consultant at Sophos
'This change in tactic from Anonymous, which allows attacks to be launched by simply clicking on a link, means that internet users need to be extremely careful when clicking on unknown URLs or they could unwittingly be joining this latest zombie army.'
'Don't forget, denial-of-service-attacks are illegal," Cluley continued.
'If you participate in such an attack, you could find yourself receiving a lengthy jail sentence.
'I'm not sure if participants in this instance would get away with claiming that they innocently clicked on links by mistake, so make sure you always trust the links you click on, even if they're shared by a friend on social networking sites.'
One of Anonymous's messages says, 'We Anonymous are launching our largest attack ever on government and music industry sites. Lulz. The FBI didn't think they would get away with this did they? They should have expected us.'
These attacks follow on from this week's internet blackout, where thousands of sites participated in protest against proposed US anti-piracy legislation.
File-sharing website Megaupload was shut down yesterday, and its founders arrested.