NEW YORK — The shadowy underworld of Internet hackers was rocked by news Tuesday that one of the world’s most-wanted and most-feared computer vandals has been an FBI informant for months and helped authorities build a case against five alleged comrades.
The FBI said it captured the legendary hacker known as “Sabu” in June, and he turned out to be Hector Xavier Monsegur, 28, a self-taught, unemployed computer programmer with no college education, living on welfare in public housing in New York.
His exploits made him a hero to some in cyberspace until he made a rookie mistake — he posted something online without cloaking his IP address, or computer identity — and someone tipped off the FBI.
Soon after his arrest, he pleaded guilty and began spilling secrets, leading to charges Tuesday against five people in Europe and the U.S., including a Chicago man, and preventing more than 300 attacks along the way, authorities said.
Law enforcement officials said it marked the first time core members of the loosely organized worldwide hacking group Anonymous have been identified and charged in the U.S.
Investigators said Monsegur and the other defendants were all associated with the group, and some were also part of the elite spinoff organization that Monsegur formed in May, Lulz Security, or LulzSec. “Lulz” is Internet slang for “laughs” or “amusement.”
Prosecutors said that among other things, the hackers, with Monsegur as their ringleader, disrupted websites belonging to Visa, Mastercard and Paypal in 2010 and 2011 because the companies refused to accept donations to WikiLeaks, the organization that spilled a trove of U.S. military and diplomatic secrets.
But it was the arrest of Monsegur that sent shockwaves through the Anonymous movement, where many described him as a leader and one of the collective’s most skilled hackers.
Some Anonymous members put on a brave face. “Anonymous is a hydra, cut off one head and we grow two back,” read one defiant message posted to Twitter.
But the atmosphere in one of the group’s chat rooms had an edge of panic. One Anonymous supporter discussed cleaning the group’s hard drive. Another warned that if Sabu is cooperating, then “we are all going to have the FBI at are (sic) door.”
Also charged with conspiracy to commit computer hacking were Ryan Ackroyd, 23, of Doncaster, England; Jake Davis, 29, of Lerwick, Scotland; Darren Martyn, 25, of Galway, Ireland; Donncha O’Cearrbhail, 19, of Birr, Ireland; and Jeremy Hammond, 27, of Chicago.
