What’s simple solution if indeed North Korea did hack Sony?

At this point, it’s what the FBI telling the world the hacking was from North Korea. The hack involve getting a master Administrator password to computers at Sony. The result ended up with private email being exposed and so on.

So let say that North Korea did in fact hacked Sony. What can be done for short term and long term solution? To me, a short term solution would be to pull plug off North Korea internet. Meaning that North Korea will only have access within its intranet network within North Korea. Basically we can call this as another sanction.