Is the FBI wrong about the fact this was a cyber attack from the government of North Korea?

This is an interesting development. The government of North Korea is willing to help with the cyber attack. 

December 20, 2014

North Korea (click here) has proposed a joint investigation with the United States into the hack attack against Sony Pictures, according to the state news agency, KCNA.

The offer comes as the FBI formally accused Pyongyang of the attack on Friday and US President Barack Obama promised to “respond proportionally” to the online breach.

North Korea says it can prove it has nothing to do with the cyberattack on Sony, the KCNA news release said....