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Hacker 'Helped US Foil Hundreds Of Attacks'
A prolific computer hacker who switched sides and helped the US government foil hundreds of cyber-attacks after being arrested is due to be sentenced.
Prosecutors in New York revealed for the first time the extent of the cooperation of Hector Xavier Monsegur, who infiltrated the servers of major corporations before helping disrupt hacks on Congress, Nasa and other sensitive targets.
The judge in the case has been asked to treat him with leniency.
After being arrested and pleading guilty three years ago, Monsegur faced decades in prison.
His sentence today could be two years or less.
The FBI estimates Monsegur helped flag up at least 300 separate attacks and prevented millions of dollars in losses after switching sides.
He is credited with helping cripple Anonymous, the notorious group of hacktivists which has been behind a number of cyber-attacks on government agencies.
Monsegur "provided, in real time, information about then-ongoing computer hacks and vulnerabilities in significant computer systems," according to prosecutors.
His aim was to steal credit card information, then sell it or use it to pay bills, when he first began hacking in a Manhattan apartment in the early 2000s, court papers say.
Monsegur said in a 2011 interview that he decided to join forces with Anonymous because of the arrest of WikiLeaks founder Julian Assange.
Using the alias Sabu, Monsegur led a splinter group of Anonymous called Lulz Security, or LulzSec, which hacked the computer systems of Fox, Nintendo, PayPal and others.
Prosecutors say the group was loosely linked with Jeremy Hammond, once the FBI's most wanted cybercriminal.
Monsegur immediately agreed to cooperate when FBI agents went to his home in the summer of 2011.
He gave them a tutorial on the inner-workings and participants in LulzSec and Anonymous.
Monsegur "convinced LulzSec members to provide him digital evidence of the hacking activities" and "asked seemingly innocuous questions that ... could be used to pinpoint their exact locations and identities".
He also talked online with Hammond while Hammond was in Chicago, and as a result, "physical surveillance teams deployed in Chicago, and an electronic surveillance unit in Washington," court papers say.
Hammond was sentenced in 2013 to 10 years behind bars.
Monsegur, whose current whereabouts are not known, became a pariah after reports of him cooperating surfaced, prosecutors said.
Hackers posted his personal information and he was approached on the street and threatened, they said.
The FBI had to relocate Monsegur and some of his family as a result.