FBI Director James Comey has confirmed the claim that the North Korean government is behind the Sony Pictures cyber attack. The hackers used proxy servers to disguise where they were coming from, but some times they failed to mask their origin. The information collected by the FBI gives a very clear indication of who was doing this, he said. Comey said most of the time, the group sent emails threatening Sony employees and made various other statements online using proxy servers. There are significant public safety issues here (and) we need to talk about it, he added.”]
Source: https://securityaffairs.co/wordpress/31941/cyber-crime/fbi-vs-northkorea-sony-pictures.html