Lloyd Korn shuts down MapleStory hackers.

Since the TS specifically asked for the legality of their actions, I would say, on the basis of intellectual property, yes, they own everything that's involved, game, info/data, music, graphics. Any form of manipulation with any of those would potentially give rise to copyright infringement. Which is the stance Nexon stands on the matter.

Would love to elaborate, but my poor drunken head refuse to think straight...