Security weaknesses in the hugely popular file-sharing Web site thepiratebay.org have exposed the user names, e-mail and Internet addresses of more than 4 million Pirate Bay users, according to information obtained by KrebsOnSecurity.com.

An Argentinian hacker named Ch Russo said he and two of his associates discovered multiple SQL injection vulnerabilities that let them into the user database for the site. Armed with this access, the hackers had the ability to create, delete, modify or view all user information, including the number and name of file trackers or torrents uploaded by users.

Russo maintains that at no time did he or his associates alter or delete information in The Pirate Bay database. But he acknowledges that they did briefly consider how much this access and information would be worth to anti-piracy companies employed by entertainment industry lobbying groups like the Recording Industry Association of America (RIAA) and the Motion Picture Association of America (MPAA), each of which has assiduously sought to sink The Pirate Bay on grounds that the network facilitates copyright infringement.

That effort has largely failed, but both industries have been busy suing individual music and movie downloaders for alleged copyright violations, often obtaining substantial monetary damages when defendants settled the charges out of court. In almost every case, the entertainment industry learned the identities of file-sharing users by subpoenaing subscriber information from Internet service providers based on the user’s Internet address.

“Probably these groups would be very interested in this information, but we are not [trying] to sell it,” Russo told KrebsOnSecurity.com in a phone interview. “Instead we wanted to tell people that their information may not be so well protected.”

Russo showed this reporter what appeared to be the user names and MD5 hashed passwords of the top administrators and moderators for the site. Russo volunteered to send me the e-mail address and hash of the password that I used to register on the site in exchange for my Pirate Bay user name. A follow-up communication showed that he did in fact have access to that information.

On Monday, I left a message requesting comment in the contact portion of thepiratebay.org, but haven’t yet received a response. I will update this post if that changes. I also sought comment from a Pirate Bay representative at the organization’s official IRC channel, but was unceremoniously kicked and banned from the channel after pasting the user names and hashed passwords of the site administrators and moderators.

Russo said The Pirate Bay administrators appear to have removed the Web site component that facilitated access to thepiratebay.org user database, although he added that he’s had no direct contact with the site administrators about his findings.

Russo, who turned 23 this week, is the creator of a subscription-based software vulnerability exploit service called Impassioned Framework. The young hacker said he is hoping to market it as a security auditing tool, although it appears to be fundamentally an exploit kit in the same vein as Eleonore and other exploit packs, toolkits designed to be stitched into a Web site and probe visitor PCs for security holes that can be used to surreptitiously install malicious software.

Tags: Ch Russo, impassioned framework, MPAA, RIAA, thepiratebay.org