A division of UK surveillance agency GCHQ launched a distributed denial of service attack (DDoS) against Anonymous, according to documents taken from the US National Security Agency (NSA) by Edward Snowden and seen by NBC News.
The revelation comes from a PowerPoint presentation prepared for a 2012 NSA conference, which details how the Joint Threat Research Intelligence Group, a unit of GCHQ, used the DDOS attack — which it called 'Rolling Thunder' — as part of efforts to disrupt Anonymous' chatrooms.
NBC noted that in launching a DDoS — a technique more commonly used by criminals as an extortion technique — the British government is the first Western government known to have conducted such an attack.
Intelligence sources familiar with the operation told NBC that the UK agency directed the DDoS attack against chatrooms where they believed "criminal hackers" were concentrated.
The DDoS attack apparently took place in the summer of 2011, mentioned by the documents as "Denial of Service on Key Communications outlets".
The presentation quotes a chatroom conversation between hacktivists. "Was there any problem with the IRC network?" asks one. "I wasn't able to connect the past 30 hours."
"Yeah," responds another. "We're being hit by a syn flood. I didn't know whether to quit last night, because of the DDoS."
In a statement GCHQ told NBC: "All of GCHQ's work is carried out in accordance with a strict legal and policy framework."