Warning: pure speculation to follow.
It’s obvious that North Korea is behind the attack on Sony in retaliation for making “The Interview” … In fact it is so obvious that it makes me suspicious.
The North Koreans say they didn’t do it … I believe them.
I think they have been set up for the fall by a much more sophisticated attacker, one who doesn’t want to take “credit” for the attack. There are two prime suspects in that case: China and Russia. In my opinion it was the Russians. Here is a recent report of their work: