The Federal Bureau of Investigation (FBI) has said that it is confident that North Korea was behind the hack attack on Sony Pictures last year because the hackers "got sloppy."
Director James Comey said that the group posted material from servers used exclusively by the North Koreans, reported the BBC.
The attack revealed treasure trove of sensitive data and caused Sony's flick, The Interview, to be shelved briefly. The movie was based on a plot to assassinate North Korean leader Kim Jong-un.
Cyber security experts are however, skeptical about the FBI's allegation.