AUSTRALIANS who helped launch cyber attacks on the websites of firms refusing to process donations to WikiLeaks face the possibility of criminal charges, a Sydney expert says.
WikiLeaks' supporters managed to temporarily bring down Visa and MasterCard websites earlier this month by overloading them with requests from individual computers.
PayPal, which also put a block on WikiLeaks' account, crashed days later.
University of Sydney Professor Michael Fry said a hacker network which orchestrated the attacks commanded thousands of members to bombard the sites after the companies stopped processing donations to WikiLeaks, which released thousands of classified government documents in recent weeks.
Those who responded to the call were potentially in breach of computer crime laws, he said.
"If readily identified, the owners of the machines participating in this ... could see themselves charged with abuse of computer facilities," said Professor Fry, a cyber-security expert with the university's School of Information Technologies.
But whether or not legal action will be taken against offending participants is a thorny issue.
"This cyber war is gathering pace and prosecutions could generate another round of attacks," he said.
"Either way we are seeing the beginning of a new era in political cyber-warfare with the widespread use of botnets."
Professor Fry said it was "fascinating and novel" that thousands of willing participants allowed their machines to be infected so they could take part in politically motivated attacks.
"This suggests a huge level of emotive support for WikiLeaks and its activities, but also a level of naivety," he said in a statement.
"It seems members of the group downloaded publicly available ... code, but took no steps to evade discovery and identification, unlike criminal botnets, which use sophisticated evasion techniques."
"This makes members vulnerable to detection, potential prosecution and counter-cyberattack(s) ... (which) have indeed happened today, initiated by US political groups."
An internet group operating under the label Operation Payback claimed responsibility for the MasterCard and Visa problems in messages on Twitter and elsewhere.