PayPal has suspended the account of a researcher who had recently demonstrated a proof-of-concept attack on SSL certificates.
The account for the researcher, Moxie Marlinspike, was used to accept donations for one of his hacking tools, called SSLSniff. At this year's Black Hat conference in Las Vegas, Marlinspike showed a way to exploit an unpatched bug in Microsoft's CryptoAPI functionality, used in some browsers to parse SSL certificates. The bug truncates addresses when certain ASCII characters are encountered. Marlinspike was able to induce a certificate authority to issue several bogus certificates.
The action to suspend Marlinspike's account followed the release of a forged PayPal SSL certificate, devised by someone with knowledge of Marlinspike's research, into the wild Monday. A post by Tim Jones on the Full Disclosure mailing list, hosted by Insecure.org., included a note accompanying the forged PayPal certificate that said: “This [certificate] is for www.paypal.com, and since the Microsoft crypto api appears to remain unpatched, it works flawlessly with SSLSniff against all clients on Windows (IE, Chrome, Safari)."
In an email to SCMagazineUS.com Wednesday, PayPal spokeswoman Sara Gorman said PayPal does not typically allow members to sell hacker tools that are designed to steal customer information.
“We consider whether there is any legitimate use in helping to strengthen the defenses of one's site when determining violation of our policy," she said. "The main difference is that the software we allow has dual purpose -- it can be used to help defenders strengthen their sites.”
Gorman did not address the fake PayPal SSL cert.