Snowden, through a NSA course that trains security professionals to think like hackers, acquired the skills he needed to quietly slip into NSA computer systems and gather the highly classified surveillance documents he leaked last month, Christopher Drew and Scott Shane of the New York Times report.

Snowden told the South China Morning Post that he took a job as an “infrastructure analyst” at Booz Allen to get "access to lists of machines all over the world the NSA hacked."