Sony cancels release of "The Interview" after unprecedented attack by N Korea cyberterrorists

Hackers backed by North Korea perpetrated an unprecedented act of cyberwarfare against Sony Pictures that exposed tens of thousands of sensitive documents and escalated to threats of terrorist attacks that ultimately drove the studio to cancel all release plans for "The Interview," the film at the heart of the attack.

Federal investigators have now connected the Sony Pictures hack to the isolated communist nation, according to an official who spoke on condition of anonymity because the official was not authorized to openly discuss an ongoing criminal case.

Earlier in the day, the besieged company said it was canceling the Christmas Day release of "The Interview." It cited the terrorist threats against movie theaters and decisions by the largest multiplex chains in North America, one after another, to pull the film from its screens.

The attack is unprecedented and possibly the costliest for a U.S. company ever, says Avivah Litan, a cybersecurity analyst at research firm Gartner.