FBI accuses North Korea of Sony hack

The FBI has named North Korea as responsible for the Sony hack which saw huge quantities of secret documents and movie details stolen, and culminated in the pulling of contentious film The Interview from theatrical release. In a statement today – and ahead of a speech from President Obama expected later on – the FBI said its investigation with Sony Pictures Entertainment along with other agencies meant it "now has enough information to conclude that the North Korean government is responsible for these actions." Exactly what happens next is unclear, though the FBI says it intends to "impose costs and consequences" on any individual, group, or nation state which conducts cyber-terrorism against US businesses.

The public naming of North Korea comes after days of speculation that hackers from the country were behind the so-called "Guardians of Peace" intrusion into Sony's systems. That group extracted a variety of internal emails, details on upcoming movies including the new James Bond film SPECTRE, and threatened further damage if Sony did not pull upcoming release The Interview.

That movie contains a controversial scene in which North Korean leader Kim Jong-un is assassinated.

"Technical analysis of the data deletion malware used in this attack revealed links to other malware that the FBI knows North Korean actors previously developed," the government agency said in a statement regarding its investigation. "For example, there were similarities in specific lines of code, encryption algorithms, data deletion methods, and compromised networks."

In addition to taking – and then publicly releasing – secrets from within Sony, the hackers also used their access to hamstring Sony Pictures Entertainment computers, and forced the company to take its network offline.

"The FBI also observed significant overlap between the infrastructure used in this attack and other malicious cyber activity the US Government has previously linked directly to North Korea. For example, 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" FBI

Sony capitulated to the hackers' demands, agreeing to axe plans to show The Interview in theaters as well as cancel any streaming or physical release of the movie.

What comes next is unclear at this stage. President Obama is expected to give a speech later today regarding the US' response to the cyber attack, and if the FBI's comments are anything to go by, it won't be just the verbal equivalent of a slap on the wrist.

"We are deeply concerned about the destructive nature of this attack on a private sector entity and the ordinary citizens who worked there ... 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 FBI said in its statement. "Such acts of intimidation fall outside the bounds of acceptable state behavior."