The hackers who breached Sony's computer network have leaked sensitive personal information on some 47,000 individuals, including celebrities, security researchers said Friday.
An analysis by the security firm Identity Finder found full names, social security numbers, birth dates and home addresses, allowing "a clear path for criminals intent on committing identity fraud."
"The most concerning finding in our analysis is the sheer number of duplicate copies of social security numbers that existed inside the files," said Identity Finder president Todd Feinman.
He said some of these numbers appeared in more than 400 different locations, "giving hackers more opportunities to wreak havoc."
The researcher found 601 files containing this data including spreadsheets and Word documents. They said more than 15,000 of the social security numbers belonged to current or former Sony employees.
Sony Pictures earlier this week confirmed the attack, calling it a "brazen" effort that netted a "large amount" of confidential information, including movies as well as personnel and business files.
F-Secure researcher Sean Sullivan said the attack "is fast becoming the worst hack any company has ever publicly suffered."
But Sullivan said that reports suggesting North Korea is behind the incident appear "implausible."
"Either the attackers are copyright reformist hackers targeting Hollywood or the attack was an attempted shakedown and extortion scheme," Sullivan said in a blog post.
"Hackers interested in copyright reform very often use better grammar than that found in the wallpaper" seen in the Sony attack.
Sullivan said extortion would be a worrisome scenario and that the leak of data may have been "to warn to other companies that may already be hacked that the extortioners aren't bluffing."
Variety has reported that unreleased Sony movies, including the upcoming "Annie," have been made available on illegal file-sharing websites.
The war film "Fury," as well as "Mr Turner," "Still Alice" and "To Write Love on Her Arms" were also made available.