After the arrest of six key members of Lulz Security (LulzSec) thanks to the alleged help of the team’s leader Hector “Sabu” Monsegur, the Internet group Anonymous has decided to respond by hacking another security firm to post its open letter to the man who betrayed the hacker community.

NEW YORK (Reuters) – One of the world's most-wanted hackers secretly became an FBI informant last year, providing evidence that led to charges on Tuesday against five other suspected leaders of the Anonymous international hacking group. In a major blow to Anonymous, which has attacked the websites of government agencies and companies around the world, U.S