It's definitive. North Korea was behind the cyberattack on Sony Pictures, the Federal Bureau of Investigation said Friday.
"As a result of our investigation, and in close collaboration with other US Government departments and agencies, the FBI now has enough information to conclude that the North Korean government is responsible for these actions," the FBI said Friday in a statement.
North Korea was identified as the culprit based on the type of attacking software used to penetrate Sony Pictures' computer networks. Those malicious programs, known as malware, are among those known to have been used by North Korea in the past, the FBI said.
The malware also included code that pointed to Internet addresses previously used by North Korea. The FBI also said the tools used to attack Sony were similar to those North Korea used against South Korean banks and media outlets.
President Obama on Friday said the US would respond "proportionally" against North Korea for the cyberattack on Sony Pictures. "They caused a lot of damage," said Obama during his year-end press conference. The president declined to offer specifics on a response, saying only that it would come "at a place and time we choose."
The anonymous group of hackers who have taken credit for breaching Sony's networks call themselves the "Guardians of Peace." Their initial attack became public on November 24, and they since have released a trove of stolen. The hackers also remotely destroyed many of Sony's computers, leaving the company's systems unusable.
North Koreaallegations of its involvement on December 7 but expressed support for the hack at the time.
"The hacking into Sony Pictures might be a righteous deed of the supporters and sympathizers with the DPRK [Democratic People's Republic of Korea]," a spokesman for North Korea said at the time.
The hackers claimed to have been motivated by a movie by Sony Pictures called "The Interview." The comedy focuses on an assassination attempt on North Korean leader Kim Jong-un. North Korean officials expressed outrage to the White House in July over the film.
For weeks, the hackers claimed they would continue to release information unless the film was canceled. After reams of embarrassing emails and documents were released, the hackers also threatened to attack any theater screening the film. On Wednesday, Sonyto pull the film from theaters for its Dec. 25 debut and said it had "no further release plans" for the movie, but reversed that stance late Friday, saying it is exploring alternative options for releasing the movie.
"The decision not to move forward with the December 25 theatrical release of The Interview was made as a result of the majority of the nation's theater owners choosing not to screen the film. Without theaters, we could not release it in the theaters on Christmas Day. We had no choice," Sony said in a statement today. "After that decision, we immediately began actively surveying alternatives to enable us to release the movie on a different platform. It is still our hope that anyone who wants to see this movie will get the opportunity to do so."
Sony's seeming switch on the film's release came after many, including actors like George Clooney, chastised the movie maker for caving into the hacker's demands. Obama also said during his press conference that Sony's initial decision to not release the film was a mistake.
"We cannot have a society in which some dictators some place can start imposing censorship here in the United States," he said. "If somebody is able to intimidate folks out of releasing a satirical movie, imagine what they start doing once they see a documentary that they don't like or news reports that they don't like."
Obama said the government will continue to engage with the film industry and the private sector on cybersecurity issues. He added that companies should anticipate future breaches but not let the possibility of hacks alter their business.
Update, 2:56 p.m. PT: Adds statement from Sony Pictures saying it is looking for alternate options for releasing "The Interview."