Anonymous claimed responsibility for the 2011 attack on HBGary Federal.
The incident followed public comments by HBGary Federal chief executive Aaron Barr about his investigation into Anonymous. In February 2011, attackers associated with Anonymous compromised the company’s systems, defaced its website, and obtained internal data, including emails.
The event drew unusual attention because the stolen material included correspondence involving cybersecurity contractors and government-related work. Anonymous publicized some of the data, turning the breach into both a technical intrusion and a major media story.
Anonymous is a decentralized collective rather than a conventional organization with a stable membership list or formal command structure. That makes attribution especially difficult: claims made under the Anonymous name do not necessarily identify every person involved. LulzSec was a separate but sometimes overlapping hacker group active around the same period.