1) "its connection to a hacking group called Lazarus that is linked to last year’s $81 million cyber heist at the Bangladesh central bank and the 2014 attack on Sony’s Hollywood studio" - https://www.reuters.com/article/us-cyber-northkorea-exclusiv...
2) "Bureau 121 is staffed by some of North Korea's most talented computer experts and is run by the Korean military." - https://en.wikipedia.org/wiki/Bureau_121#cite_note-reuters-1
3) "The wannacry ransomware has a link to suspected North Korean hackers" - https://www.wired.com/2017/05/wannacry-ransomware-link-suspe...