"North Korea's offensive hacking program is surprisingly well documented by defector accounts and by efforts to trace back previous hacks to their source. By all accounts, despite the fact that the vast majority of North Koreans are kept offline and unaware of the internet for their entire lives, the military still maintains a large and highly professionalized cyberwarfare division.

This is how it works, according to defector accounts: promising young talent is recruited out of school. They study at a special school in Pyongyang for five years and are then sent to train in China or Russia, both of which run sophisticated state run cyberwar divisions. These assignments are considered some of the most prestigious in the country and are rewarded with special privileges, housing, and higher status. This is an earnest reflection of how seriously North Korea takes cyberwar, but it's also meant to reduce the risk that their internet access, which gives them knowledge of the outside world, will tempt them into defecting."