Yes to the degree that they know something about it. If the perpetrators are not in NK or working for them, then I don't see how NK gov. could prove they didn't do it.
That is, the best NK could do to prove they aren't to blame is by outing someone within and claiming it wasn't an operation condoned at higher levels.
It would be a win win for them then. They can say "yeah we hate the movie and dislike the US. Yes we told some people to try and hack and shame the US. No we didn't know or approve of them accomplishing it by trying to ruin SPE." They could avoid starting a war that way, but still gain "credit". Also they would look good by publicly saying "yeah this was bad; we would never officially approve of what was done".
My question back; if they weren't involved, how could they possibly prove they didn't do it?
The only way to prove they didn't do it would be by having someone under their control involved in doing it?