By Barry Eitel

SAN FRANCISCO

North Korea has been linked to a massive cyberattack at Sony Pictures Entertainment last week, according to media reports Monday.

The FBI is investigating the hacking and the film studio has hired forensics unit Mandiant of the security firm FireEye, according to sources speaking to Reuters.

Employees found themselves locked out of Sony’s computer network on Nov. 24. Instead of the company's system, they found monitors flashing with a red skeleton and the phrase “Hacked By #GOP,” an acronym for “Guardians of Peace.”

Sony has not commented on the scope of the attack, but anonymous sources claim the hack crippled the studio for several days.

“Every PC in the company is useless and all of the content files have either been stolen or destroyed or locked away,” according to a source close to the matter speaking to entertainment news site The Wrap.

By Monday, critical commercial systems were back online, and company email is expected to return Monday as well.

The progress, however, could not stop a slew of Sony releases from hitting the Internet – most likely leaked by the hackers.

Five films have leaked since last week, including "Fury," which was released in theaters earlier this month. Other leaked movies, including the musical "Annie" and drama "Still Alice," have not yet been released 

It is believed that the Guardians of Peace are working for the North Korean government, perhaps through China. The North Korean government has raged about the Sony Pictures film "The Interview," slated for a Christmas Day release.

In the comedy movie, James Franco stars as a talk-show host with Seth Rogen playing his producer and best friend. After Franco’s character scores an interview with North Korean dictator Kim Jung-un, the duo is asked by the United States government to assassinate the autocratic leader.

North Korea, which has been linked to recent cyberattacks against South Korea, called the film “an act of war.”

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