WASHINGTON — The FBI said Thursday that it had served more than 40 search warrants throughout the United States as part of an investigation into computer attacks on websites of businesses that stopped providing services in December to WikiLeaks.
The FBI statement announcing the search warrants was the first indication that the U.S. intends to prosecute the so-called "hacktivists" for their actions in support of WikiLeaks.
The search warrants were executed on the same day authorities in Great Britain announced that they had arrested five people in connection with the attacks, which temporarily crippled the websites of Amazon.com, PaylPal, MasterCard, Visa, the Swiss bank PostFinance and others.
FBI officials were unavailable for comment, and the statement did not say who was served or where the searches were conducted. The statement noted that attacks, known as distributed denial of service attacks and which use easily available software to shutdown a computer network by flooding it with millions of requests for information, violate federal law and are punishable by a prison sentence of 10 years.
The statement noted that a group known as "Anonymous" had claimed credit for the attacks. Anonymous is also believed responsible in recent days for attacks on government websites in Tunisia and Egypt.
British news reports said three of the five arrested were teenagers, aged 15, 16 and 19, and that the others were 20 and 26 years old. Dutch police last month arrested two teenagers suspected of involvement in the online campaign.
The attacks were organized through social networking sites such as Twitter in the days after WikiLeaks began publishing U.S. State Department cables that apparently had been downloaded by an American Army private serving in Iraq. Their first target was Amazon.com, which, at the behest of U.S. Sen. Joseph Lieberman, I-Conn., had stopped hosting the WikiLeaks website.
They spread to PayPal, MasterCard and Visa after those businesses declined to process credit card payments destined to WikiLeaks.
PostFinance, a bank operated by Switzerland's postal service, also closed an account that was registered to Julian Assange, WikiLeaks' founder. The account number had been published on the WikiLeaks website with a solicitation for donations. PostFinance said it closed the account because Assange was not a resident of Switzerland, as Swiss law required.
The attacks did no long-term damage and in most cases only lasted a few hours. But legitimate would-be users were unable to contact the sites while the attacks were underway.
The FBI said it is working with several European governments and the National Cyber-Forensics and Training Alliance (NCFTA) to identify the source the attacks, which the FBI attributed to a type of software it identified as "Low Orbit Ion Canon" tools. It said major anti-virus programs had been updated to block such software.
Previously, the only known criminal investigation stemming from WikiLeaks' publication of thousands of U.S. State Department cables was one that seeks to tie WikiLeaks' founder Julian Assange to Army Pfc. Bradley Manning, who is suspected of providing the cables to the website. In December, a federal magistrate in Alexandria, Va., issued a search warrant to Twitter demanding the records of five of its users, including Assange and Manning.
It was not known late Thursday whether those records had been surrendered.
MORE FROM MCCLATCHY
Follow McClatchy on Twitter.