Read as much as you want on BostonGlobe.com, anywhere and anytime, for just 99¢.

Prosecutors: Hacker aided FBI

NEW YORK — A computer hacker who infiltrated major corporations later switched sides and helped the government disrupt hundreds of cyberattacks on Congress, NASA, and other sensitive targets, federal prosecutors said.

They detailed the cooperation of Hector Xavier Monsegur for the first time in court papers while asking a judge to reward him with leniency at his sentencing Tuesday. They credited him with helping them cripple Anonymous, “hacktivists” who stole confidential data, defaced websites, and temporarily put some victims out of business.

Continue reading below

Monsegur provided “information about then-ongoing computer hacks and vulnerabilities in significant computer systems,’’ prosecutors wrote. The FBI estimates he helped prevent millions of dollars in losses. After his 2011 guilty plea, he faced two decades behind bars; now, the sentence could be two years or less.

Monsegur led an Anonymous splinter group called Lulz Security. Reports he was cooperating with the FBI made him a pariah in the movement, and harassment prompted the government to relocate him.

Loading comments...

You have reached the limit of 10 free articles in a month

Stay informed with unlimited access to Boston’s trusted news source.

  • High-quality journalism from the region’s largest newsroom
  • Convenient access across all of your devices
  • Today’s Headlines daily newsletter
  • Subscriber-only access to exclusive offers, events, contests, eBooks, and more
  • Less than 25¢ a week