Like you, I want the facts. I have seen no facts that implicate the DPRK over the people who claimed responsibility initially (GOP). Wired had an article on it two days ago when the first stories started to attempt to pin the hack on the DPRK which has been ignored by all US and UK media. Not only have all US media outlets jumped on the "it was those dirty North Koreans" bandwagon, but the BBC has become complicit in this as well.
I fairness, I was able to do some digging to find more information on the BBC that I could not in US media. Let me go through the evidence. and comment on each after that.
Before doing so, let me explain something critical. In order to teach hacking, a person has to have access to the internet. This is a huge dilemma for the DPRK who has to risk any Internet access with the knowledge that the person with access _WILL_ see information damaging to their loyalty to the DPRK. There are no computer cafe's in North Korea where guys can go learn to hack to make a couple extra bucks, in fact unless you have explicit Government approval you can not have a computer. Even if you are a "tourist" you must have permission and you will not be able to take your laptop wherever you wish.
This means that the only hacking that could come from the DPRK is Government sponsored, and the amount of hackers they have would be tiny. They don't have the money for "new" or unique equipment either, so any computer hardware they have is going to be 2nd hand junk that China no longer wants. What the Military has for hacking tools would be 2nd hand script kiddie tools or, provided by China.
Not only does an extraordinary claim require extraordinary proof, but in this case US Politicians have lied so often I don't trust a damn thing I'm told any longer. Our "media" follows the scripts they are handed just like the politicians, and I don't trust them either. So here is the claim summary.
First, the FBI says its analysis spotted distinct similarities between the type of malware used in the Sony Pictures hack and code used in an attack on South Korea last year.
So we turn to another, better clue: IP addresses - known to be part of "North Korean infrastructure" - formed part of the malware too. This suggests the attack may have been controlled by people who have acted for North Korea in the past.
That's it folks, that is all we have. The "Hacks" last year (actually since 2009) which were never tracked to the DPRK are the first reason they believe this hack was. Wow, that's quite a leap in logic. DarkSeoul is still anonymous and there is no evidence that links them to North Korea. Lots of claims that China is training and letting the DPRK use their resources, but no evidence that the group is even operating out of China. Finally we have IP addresses, which any Script kiddie knows to spoof with someone's IP address you hate! I'm positive that the FBI can not be that goddamn dumb, they have to realize IPs can be spoofed too!
Ok, time to get off my soap box...