FBI malware warning follows Sony Pictures hack

The FBI has warned that hackers have used malware to launch destructive attacks against businesses in the United States, following a devastating attack on the networks of Sony Pictures Entertainment.

In a five-page confidential "flash" warning sent to businesses late Monday and seen by Reuters, the FBI provided technical details about the malware, but did not mention the corporate victim by name. According to the advisory, the malware is particularly violent -- overwriting data on hard drives to make them little more than bricks while also closing down networks.

While it is likely the malware in question is linked to the Sony hack -- considering the timing of the issued warning -- an FBI spokesman declined to comment on the advisory. If this malware was used in the Sony security breach, the recovery process is likely to be costly and time consuming.

Last week, reports emerged that noted Sony Pictures' websites and a number of Twitter feeds had been temporarily taken over. At the same time, employees of Sony's entertainment arm logged in to their systems to discover a message left by a hacking group -- or an individual -- which identified themselves as "#GOP" -- Guardians of Peace.

The message left on Sony Pictures' internal network made demands of the company, promising to release "secrets" if the demands were not met.

Following this declaration, packs of files allegedly belonging to Sony Pictures found their way online. Data including passwords, Outlook mailboxes, personal employee data and copies of passports belonging to both actors and crews working on film projects have been released.

Several days later, Sony Pictures films not yet officially released were leaked, including the titles "Fury," "Still Alice," "Annie," "Mr. Turner" and "To Write Love On Her Arms."

According to reports, Sony Pictures has been forced to bring in FireEye's Mandiant forensic team to investigate the breach and to act as clean-up crew. The FBI is also investigating the cyberattack.

A Sony spokesperson said the "theft of Sony Pictures Entertainment content is a criminal matter, and we are working closely with law enforcement to address it."

As reports tentatively linked the cyberattack against Sony Pictures to the release of a film about North Korea's leader Kim Jong-un, the country's officials responded in a rather cryptic manner. Speaking to the BBC, when asked whether North Korea was responsible for the attack, a spokesman for the North Korean government said "Wait and see."

The film in question, "The Interview," is about two reporters who are enlisted by the CIA to assassinate Kim Jong-un. Earlier this year, North Korea complained about the film to the United Nations and branded the movie an "undisguised sponsoring of terrorism."

This story originally appeared at ZDNet under the headline "FBI warns of 'destructive' malware following Sony hack."