Some of the Excel files have a column for "paymenttype" although the fields are mostly blank.
Efforts to reach Friend Finder Networks to verify the files were not successful.
The forum is a so-called "hidden" website hosted on the Tor network, which helps masks the site's true IP address.
The site can only be reached using the Tor Web browser.
"I assumed it was some type of extortion."She eventually wrote a blog post on April 13, which didn't name Adult Friend Finder but identified the online nickname of the person who leaked the files, whose goes by ROR[RG].
As of January 17, 2010, Friend Finder Networks had a negative net worth equal to 8 million, million in cash on hand and 0 million in liabilities.Bev Robb, who does malware and dark Web research, came across the Adult Friend Finder files in March.She said she held off on publicizing the information for a few weeks before contacting two security experts."I really didn't know what to do with the data," she said.Friend Finder Networks wrote that it had hired Fire Eye's forensics unit, Mandiant, to investigate along with Holland and Knight, a law firm, and a public relations company specializing in cybersecurity."We cannot speculate further about this issue, but rest assured, we pledge to take the appropriate steps needed to protect our customers if they are affected," it said.The company could not be reached for further comment.