North Korea praised the cyberattack on the Sony Corp. that exposed confidential company information and froze Sony Pictures Entertainment’s computer network, but it denied responsibility for the hacking, NBC News reported Sunday. The Sony Pictures unit is releasing Christmas Day an action-comedy film titled “The Interview,” in which CIA agents plot to assassinate North Korean leader Kim Jong Un.

An unidentified representative of the country’s National Defense Commission said the cyberattack “might be a righteous deed of the supporters and sympathizers” of North Korea’s call for the rest of the world to fight in a “just struggle” against American imperialism.

“We do not know where in America the Sony Pictures is situated and for what wrongdoings it became the target of the attack,” the statement carried by state media said. “But what we clearly know is that the Sony Pictures is the very one which was going to produce a film abetting a terrorist act while hurting the dignity of the supreme leadership of [North Korea].”

The Kim family has ruled North Korea for three generations and frequently denounced mockery of its leaders as attacks on the nation’s sovereignty. 

The hackers behind what has been called an unparalleled cyberattack on Sony Pictures Entertainment intended to both destroy property and leak sensitive information, a forensic investigator wrote in an email to Sony Corp. CEO Michael Lynton. The email did not include details on the hackers’ identities or the full extent of the damage to the company, Reuters reported. The cyberattack used malware to wipe the drives of personal computers, rendering them inoperable and forcing the firm to either manually replace them or re-image them. Both repairs are expensive.

The attack was made public Nov. 24 when Sony workers received an email from the hackers with an image of a skeleton and the text “Hacked by #GOP,” the acronym of the hacker group Guardians of Peace. It also exposed confidential information, including personal details of 6,000 employees and even bankers who have worked with Sony Pictures. Several files of movies that have yet to hit theaters were posted online as well and have already been viewed millions of times.

Cybersecurity experts estimate the attack will cost Sony tens of millions of dollars, the Los Angeles Times reported.

The malware was so sophisticated there was little Sony could have down to thwart the hack, according to some cybersecurity experts.

“This incident appears to have been conducted using techniques that went undetected by industry standard antivirus software,” the FBI said in a statement  Saturday.

In an e-mail to Sony staff obtained by USA Today, Kevin Mandia, CEO of Mandiant, the security company analyzing the attack, concurred, saying, “The malware was undetectable by industry standard antivirus software and was damaging and unique enough to cause the FBI to release a flash alert to warn other organizations of this critical threat.”

Mandia said that “this was an unparalleled and well planned crime, carried out by an organized group, for which neither SPE nor other companies could have been fully prepared.”