FBI: North Korea Behind Sony Cyber-Attack

An investigation into the Sony (Swiss: SONC.SW - news) cyber-attack has determined the North Korean government was behind the operation, the FBI says.

The agency said a "significant overlap" existed between the infrastructure used in the Hollywood studio hack and previous malicious cyber activity linked to North Korea.

A technical analysis of data deletion malware used in the data breach also provided links to malware previously developed by North Korean actors, the FBI said.

"North Korea's actions were intended to inflict significant harm on a US business and suppress the right of American citizens to express themselves," the agency said in a statement.

"Such acts of intimidation fall outside the bounds of acceptable state behaviour.

President Barack Obama said on Friday the US will "respond proportionally at a time and manner that we choose" .

North Korea has denied being behind the attack.

The Obama administration has called the devastating cyber-attack a serious national security matter.

A US official, who spoke on condition of anonymity, told Reuters the probe revealed a possible Chinese link either through collaboration or through the use of Chinese servers.

But Mr Obama had said there was not indication North Korea was acting in conjunction with another country.

China initially responded to the allegations by urging the US to share evidence that pointed to a possible Chinese link.

A US official told Reuters that the US was working with China, Japan, South Korea and Russia in seeking assistance on reining in North Korean cyber-attacks.

The hack prompted Sony Pictures on Wednesday to cancel the release of the comedy The Interview , which depicted a plot to assassinate North Korean leader Kim Jong-Un.

The decision to pull the film was made after the group claiming responsibility for the cyber-attack made terrorist threats against US cinemas that showed the movie.

Mr Obama on Friday said the move was a "mistake" and he wished Sony would have come to him beforehand.

The hackers, who call themselves Guardians of Peace, praised the decision to cancel the film's release in a statement provided to CNN on Friday.

The group also said it would keep Sony's data secure if the company continued to comply.

"It's very wise that you have made a decision to cancel the release of The Interview," the message said, according to CNN.

"We ensure the security of your data unless you make additional trouble."

A host of Hollywood stars have slammed the decision to cancel the film's release .

Former US Senator Chris Dodd, now the Chairman and CEO of the Motion Picture Association of America (MPAA), issued a statement calling North Korea's actions a "despicable, criminal act".

"This situation is larger than a movie's release or the contents of someone's private emails, Mr Dodd said.

"This is about the fact that criminals were able to hack in and steal ... and threaten the livelihoods of thousands of Americans who work in the film and television industry, as well as the millions who simply choose to go to the movies."

US Homeland Security Secretary Jeh Johnson said the Sony cyber-attack underscores the need for US businesses and government to co-operate on improving cyber-security.