WinAmp's ‘malicious MP3’ vuln

All you need is an upgrade

Users of NullSoft's popular WinAmp player should upgrade to version 2.80 (available here) to avoid a vulnerability reported on the BugTraq mailing list by Swedish security researcher Andreas Sandblad and confirmed by the company.

What we have here is a buffer overflow condition which can be exploited, with some difficulty, by using the ID3v2 tag which contains information about the audio file, such as artist, title, images, etc. It can also contain quite a bit more than that. Indeed, it can contain a separate file and can be as much as 256MB in total size.

WinAmp parses the tag's contents, and of course manipulation here is limited to what the parser is designed to accomplish. There's a lot that can't be done with this rig -- and there's probably a lot that isn't known about what can be done -- but do know that if the mini-browser is enabled, a malformed URL can cause a buffer overflow.

"If the mini-browser is enabled, Winamp will try to query a script on info.winamp.com for extra information about the song, based on data from the ID3v2 tag. The buffer overflow condition occurs when the URL string intended to be sent to the minibrowser is created. That means the buffer overflow occurs before any actual Internet connection to info.winamp.com is made," Sandblad says.

Creating the actual condition is fairly straightforward, but exploiting it isn't quite so easy. However it is possible to get to a memory address where considerable mischief can be done. This would include infecting other MP3 files on a drive or a network share. How long the blackhat development community will take to produce a handy exploitation tool is anyone's guess, but generally speaking they catch on very fast. Obviously it wouldn't hurt to upgrade from 2.79 to 2.80, since doing so is free and, we hope, painless. In lieu of that, a simple workaround is to disable the mini-browser.

Personally, I'd do both if I were using the product. ®

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