Since no information has yet been published about a vulnerability I recently discovered in Winamp, and the issue has raised some interest, here are the details.
Recently, while listening to some music via Winamp (my favorite media player), I recalled an old Winamp Buffer-Overflow vulnerability found by Leon Juranic in 2005.
Leon found that since Winamp didn't expect long inputs in mp3 id3 tags, a buffer-overflow attack was possible by playing specially crafted mp3 files with lengthy tags.
Knowing that Winamp uses an embedded browser in various places, I decided to take a closer look at it and see what could be done... ;)
Winamp's "Now Playing" feature uses an embedded browser to present information about the currently played media file. When the user plays a media file, some of the file's metadata is embedded into the HTML that the embedded-browser displays.
Furthermore, due to the integration between the embedded browser and the Winamp application, this script injection vulnerability has some unique characteristics.
In many cases, Desktop applications that utilize IE embedded browsers render the HTML content in a highly privileged zone called "My Computer Zone". This zone allows the programmer to perform a wide range of actions on the computer and thereby to "interact" with the hosting application. The downside of this (fairly common) approach is that if the application is susceptible to XSS, a malicious attacker might be able to exploit it and gain full system control over the victim's system. (Aviv Raff did some great work in this field, "Skype cross-zone scripting vulnerability" being a well-known example.)
Winamp's programmers were probably aware to this security threat and therefore chose a different approach. Instead of creating and loading a local file that contains all the relevant data (e.g. data about the song retrieved from the Internet and data originated from the id3 tags of the mp3 file) in a privileged security zone, Winamp loads the embedded browser with a page located in http://client.winamp.com (Internet URL - non-privileged zone).
The attack could then be taken one step ahead, by trying to identify functions that are susceptible to memory-based attacks or logical attacks (Reading/Writing of information from/to the victim's host and even gaining full system control in the form of executing commands).
I would like to thank Winamp's team for their quick responses and the efficient way in which they handled this security issue.