The FBI on Friday announced that "the North Korean government is responsible" for the cyber attack on Sony Pictures Entertainment.
The agency said it could not divulge all the information that led it to place the blame on North Korea. But there are at least three things that it can share: malware used in the Sony hack is linked to malware that North Korea has used in other attacks; there is "significant overlap" between the infrastructure used in the Sony attack and hacks pulled off by North Korea; and the tools used in the Sony attack are similar to those used against South Korean banks in 2013.
"We are deeply concerned about the destructive nature of this attack on a private sector entity and the ordinary citizens who worked there," the FBI said today. "Further, North Korea's attack on SPE reaffirms that cyber threats pose one of the gravest national security dangers to the United States."
"North Korea's actions were intended to inflict significant harm on a U.S. business and suppress the right of American citizens to express themselves," the agency continued. "Such acts of intimidation fall outside the bounds of acceptable state behavior."
As for the evidence, the FBI pointed to "similarities in specific lines of code, encryption algorithms, data deletion methods, and compromised networks" between the Sony hack and previous attacks that have been linked to North Korea.
Meanwhile, "the FBI discovered that several Internet protocol (IP) addresses associated with known North Korean infrastructure communicated with IP addresses that were hardcoded into the data deletion malware used in this attack," the agency said.
The attack was reportedly carried out months ago, but did not make headlines until November, when Sony Pictures' employees had their PCs compromised and network shut down. In the days after the breach, there were reports that North Korea was involved, but experts have gone back and forth over whether that was even possible (North Korea has denied any involvement).
Why would North Korea hit Sony? The studio was gearing up to release The Interview on Christmas Day, a film that depicts a plot to kill North Korean leader Kim Jong-un. As a result, the cyber attack was viewed as retaliation for the film, pulled off by a group that goes by the name Guardians of Peace (GOP).
More recently, GOP threatened 9/11-style violence against theaters that showed The Interview, prompting major theater chains to pull the movie from its lineup and Sony to scrap the film's release altogether.
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