Using “web crawler” software designed to search, index and back up a website, Mr. Snowden “scraped data out of our systems” while he went about his day job, according to a senior intelligence official. “We do not believe this was an individual sitting at a machine and downloading this much material in sequence,” the official said. The process, he added, was “quite automated.”
The findings are striking because the N.S.A.’s mission includes protecting the nation’s most sensitive military and intelligence computer systems from cyber attacks, especially the sophisticated attacks that emanate from Russia and China. Mr. Snowden’s “insider attack,” by contrast, was hardly sophisticated and should have been easily detected, investigators found.'