FBI Director James Cormey says that the North Korean’s who hacked Sony were tracked because of bad operational security in their use of proxies.
We saw the same thing with the take down of the Silk Road website. Few people have the skills, tools, and discipline to be 100% consistent with their anonymity. Any slip at any time can blow your cover. Of course, this could have been an intentional false flag, the rabbit hole can get very deep. Jeff Carr makes the case that this is actually quite likely.
"FBI Director James Comey, today, said that the hackers who compromised Sony Pictures Entertainment usually used proxy servers to obfuscate their identity, but "several times they got sloppy."
Speaking today at an event at Fordham University in New York, Comey said, "Several times, either because they forgot or because of a technical problem, they connected directly and we could see that the IPs they were using ... were exclusively used by the North Koreans."