On November 14 , 2015 Anonymous posted a video announcing its " biggest operation ever " against the terrorist group in response to the attacks in Paris , taking down 3,824 pro-ISIS Twitter accounts and doxxing recruiters . A message posted by an ISIS-affiliated account on encrypted chat service Telegram replied defiantly to Anonymous by providing instructions on how to respond to a potential cyberattack . On 25 November , an ISIS WordPress dark web site was reportedly hacked by GhostSec , which replaced the site with an advert for Prozac
attacks in Paris
November 2015 Paris attacks
Ghost Security