British spy agency GCHQ ran denial-of-service attacks against chat rooms in a bid to disrupt efforts by the Anonymous and LulzSec collective to run their own DDoS campaigns against firms including PayPal and Visa, documents taken by former NSA contractor Edward Snowden reveal.
The documents, obtained by NBC News, show that a previously unknown GCHQ unit, the Joint Threat Research Intelligence Group (JTRIG), used a DDoS attack - which it dubbed Rolling Thunder - to scare off Anonymous members from chat rooms where they planned their own attacks.
The JTRIG took action in the wake of 2011's 'Operation Payback', which saw Anonymous target financial services firms - including PayPal, MasterCard and Visa - with DDoS attacks in retaliation for the blockade of payments to the whistleblowing Web site WikiLeaks.
In addition to knocking out chat rooms through DDoS attacks to disrupt communications between Anonymous members, GCHQ agents also posed as hacktavists to gather intelligence, a PowerPoint presentation shows.
In one case, the agents managed to identify a hacker, 'GZero', as Edward Pearson who was sentenced to 26 months in prison for stealing information from 200,000 PayPal accounts.
GCHQ insists that it acted within the law but some of the hacktavists targeted have reacted with incredulity. Chris Weatherhead, who last year was sentenced to 18 months in prison for his part in Operation Payback, tweeted: