A spreadsheet allegedly containing personal information of Sony employees -- including several executives' salaries and the Social Security numbers of 3,803 employees -- leaked online. Fusion published portions of the spreadsheet on its website on Monday.
Sony was not immediately available for comment.
When Sony workers tried to log onto their computers last week, they were greeted with an image of a skeleton accompanied by the text "Hacked By #GOP."
The message, which contained multiple threats, appeared to be an attempt to blackmail Sony by a group calling itself Guardians of Peace. The attack resulted in the pirating of DVD copies of at least five movies, including Brad Pitt's "Fury" and the upcoming musical "Annie."
The FBI confirmed Monday that it is investigating the matter. Sony has also enlisted Mandiant, a cyberforensics unit of the security firm FireEye, to assist in the search for the hackers.
"To regain confidence in the integrity of their network, it’s not a matter of plugging one hole or another because there’s likely so many back holes inserted that it needs to be brought back from scratch," Clifford Neuman, director of the USC Center for Computer Systems Security, told The Times. "They’ll need to re-architect the security of their entire environment."
Some speculated that hackers in China working on behalf of North Korea could be responsible.
North Korea propaganda outlets have promised retaliation against the U.S. if "The Interview" is released. The film, which hits theaters Dec. 25, is not among those that have popped up on file-sharing sites.
When asked about potential involvement in the attack, a spokesman for the North Korean government told the BBC: "Wait and see."
Staff writers Ryan Faughnder and Paresh Dave contributed to this report.
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