User blog comment:Volknur/The Problem with PvP in Dark Souls/@comment-11388043-20130711205752/@comment-4511886-20130712103158

I don't think they're allowed to since they don't own the connection, which they will in DaS 2.

It's up to GFWL/Xbox LIVE/PSN to ban hackers. Something they aren't very good at.