FBI's conclusion followed technical analysis of the data deletion malware used in the attack that revealed links to other malware that the FBI knows North Korean actors previously developed. For example, there were similarities in specific lines of code, encryption algorithms, data deletion methods, and compromised networks.
The FBI also observed significant overlap between the infrastructure used in this attack and other malicious cyber activity the U.S. 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.
Separately, the tools used in the Sony attack have similarities to a cyber attack in March of last year against South Korean banks and media outlets, which was carried out by North Korea.
"We are deeply concerned about the destructive nature of this attack on a private sector entity and the ordinary citizens who worked there. Further, North Korea?s attack on SPE reaffirms that cyber threats pose one of the gravest national security dangers to the United States," the FBI said.
Sony Pictures Entertainment has decided to call off the Christmas release of "The Interview" movie, following warnings by the alleged hackesrs that that they would continue leak "sensitive" documents online. Hackers sent a new email Friday to Sony Pictures Entertainment warning not to distribute the film "in any form,"for instance, DVD or piracy," wrote the hackers.