'The Interview' -- North Korea Definitely Behind the Hack ... FBI Says

The FBI is confirming North Korea is responsible for the cyber attack on Sony Pictures -- and it has a ton of evidence to back it up.

The agency says the North Korean government's fingerprints are all over the attack -- which used specific malware and IP addresses connected to previous attacks ... that it knows were carried out by N. Korea.

The FBI is treating the hack as an act of terrorism intended to "inflict significant harm on a U.S. business and suppress the right of American citizens to express themselves."