Additionally, there is an estimate (from a facially plausible source) that North Korea has as many as 10,000 people working in IT outsourcing http://cacm.acm.org/magazines/2012/8/153816-inside-the-hermi... (yes, despite the fact that the IT firms don't have full Internet access). It also has to be pointed out that Sony's famously not the hardest target in cyberwarfare.