They're more of an annoyance than anything else. The strategy so far seems to have been to wait it out and hope their crazy cult-regime finally collapses. I don't see any reason anyone would want to expedite this unless they thought there was a clear and present danger of NK escalating in both belligerence and power in the near future. I can imagine the former, but not the latter.
The Korean War was in many ways similar to a "more power" version of Ukraine today.
I obviously don't know the story behind this. The point is, there are plenty of opportunistic and self-serving domestic interests who probably don't either but can nevertheless turn this hack into a very beneficial event, regardless of who did it. From their perspective, NK being the source is actually the best-case scenario.
Plus their prison camp system, internal mass famines, brutal authoritarian dictatorship.