LONDON — A broad campaign of cyberattacks appeared to be under way on Wednesday in support of the beleaguered antisecrecy organization WikiLeaks, which has drawn governmental criticism from around the globe for its release of classified American documents and whose founder, Julian Assange, is being held in Britain on accusations of rape.
Attacks were reported on Mastercard.com, which stopped processing donations for WikiLeaks; on the lawyer representing the two Swedish women who have accused Mr. Assange of sexual improprieties; and on PostFinance, the Swiss postal system’s financial arm, which closed Mr. Assange’s account after saying he provided false information by saying that he resided in Switzerland.
At least some of the attacks involved distributed denials of service, in which a site is bombarded by requests from a network of computers until it reaches capacity and, effectively, shuts down.
It was unclear whether the various attacks were independently mounted, but suspicion was immediately focused on Anonymous, a leaderless group of activist hackers that had vowed to wreak revenge on any organization that lined up against WikiLeaks and that claimed responsibility for the Mastercard attack.
The group, which gained notoriety for their cyberattacks on targets as diverse as the Church of Scientology and the rock musician Gene Simmons, released two manifestos over the weekend vowing revenge against enemies of WikiLeaks.
“We fight for the same reasons,” said one. “We want transparency and we counter censorship.”
The manifestos singled out companies like PayPal and Amazon, who had cut off service to WikiLeaks after the organization’s recent release of classified diplomatic documents from a cache of 250,000 it had obtained.
In recent days, Gregg Housh, an activist who has worked on previous Anonymous campaigns, said that a core of 100 or so devout members of the group, supplemented by one or two extremely expert hackers, were likely to do most of the damage. Mr. Housh, who disavows any illegal activity himself, said the reason Anonymous had declared its campaign was amazingly simple. Anonymous believes that “information should be free, and the Internet should be free,” he said,
Mr. Assange was jailed in Britain on Tuesday after being denied bail in a London court hearing on a warrant for his extradition to Sweden to face accusations of sexual offenses. On the courthouse steps, his lawyer, Mark Stephens, told reporters that support shown for Mr. Assange and WikiLeaks so far was “the tip of the iceberg.”
In words that now seem prophetic, he added that the battle for WikiLeaks and its founder’s future was “going to go viral.”