> The attacks at Sony were routed from command and control centers across the world, including a convention center in Singapore and a computer at Thammasat University in Thailand. But one of those command and control servers, a computer in Bolivia, had been used before, in a limited set of cyberattacks on South Korean targets two years ago.

The evidence has to be better than this to make an accusation against a state. Botnets overlap a lot because the way they are built is with automated scanners that take advantage of common vulnerabilities. It isn't uncommon to find a botnet client that has been hacked a half-dozen other times and has had rootkits installed each time. A large part of sophisticated botnet droppers is removing all the previously installed botnets on a server where a vulnerability has been found.

Having one client in common with another attack network is a low or insignificant figure.

Similar applies to common modules found in other malware. Authors reverse engineer and re-appropriate techniques or libraries from other successful malware all the time. That is also not evidence of a link to North Korea.