Originally Posted by Sly

More info: Stop Saying North Korea Didn't Hack Sony - Business Insider

North Korean intelligence defectors are also saying they fully believe it's North Korea. Apparently they have a very advanced hacking unit. One of the tasks these hackers get when first hired on is living in their assigned enemy country and learning the culture, examples: South Korea, Japan, United States. If true, one of those intelligence officers could have gotten a job at Sony, learned some of the framework and used that as a basis for the attack.