The NSA knew North Korea hacked Sony because it hacked North Korea first
 

The US government recently took the rare step of directly blaming North Korea for the crippling hack of Sony in retaliation for its satire film, The Interview. But how could it be so sure in the face of doubters, who said another hacking group disgui...

http://www.engadget.com/2015/01/19/n...=rss_truncated