Anonymous got lucky. When five of its hackers attacked security company HBGary Federal on February 6, 2011, they were doing so in order to defend the group’s privacy. It wasn’t because they hoped to reveal plans to attack WikiLeaks, create surveillance cells targeting pro-union organizations, and sell sophisticated rootkits to the US government for use as offensive cyber weapons—but that’s what they found. In the weeks after the attack, the hackers released tens of thousands of e-mail messages and made headlines around the world. Aaron Bar, the CEO of HBGary Federal, eventually resigned; 12 Congressman called for an investigation; an ethics complaint was lodged against a major DC law firm involved with some of the more dubious plans. Join Ars' editors as they dig into the secret world of Anonymous and hackers for hire in Unmasked.