MegaSWF - Persistant Cross Site Scripting Vulnerability

Document Title:
===============
MegaSWF - Persistant Cross Site Scripting Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=368


Release Date:
=============
2012-01-12


Vulnerability Laboratory ID (VL-ID):
====================================
368


Product & Service Introduction:
===============================
Do you create Flash games, Flash animations, or any other type of content saved in the .SWF extension? MegaSWF
offers you a free, stable .SWF file repository on our high-speed servers.

To take advantage of our service, simply click the Upload button. You can also create an account with MegaSWF
for more capacity and more functionality. We are always adding new features based on the feedback we get from
our users.

(Copy of the Vendor Homepage: http://megaswf.com/about)


Abstract Advisory Information:
==============================
A Vulnerability-Lab Reseacher discovered a persistent cross site scripting vulnerability on the MegaSWF website.


Vulnerability Disclosure Timeline:
==================================
2011-12-03:	Vendor Notification
2012-01-12:	Public or Non-Public Disclosure


Discovery Status:
=================
Published


Exploitation Technique:
=======================
Remote


Severity Level:
===============
Medium


Technical Details & Description:
================================
A persistent cross site scripting vulnerability is detected on the MegaSwf website service.
The vulnerability allows an remote attacker with required user inter action to hijack customer sessions via persistent cross site scripting.
Successful exploitation can result in account steal, client side exploitation or phishing & session hijacking.
The bug is located on the serve module in-/output of the megaswf service web application.

Vulnerbale Module(s):
                                                                    [+] serve

Picture(s):
                                                                    ../1.png


Proof of Concept (PoC):
=======================
The vulnerability can be exploited by remote attacker with required user inter action.
For demonstration or reproduce ...

PoC:
[1] Create an URLRequest-Object with a JS-Code like : var alert:URLRequest = new URLRequest("javascript:alert('xss')");
[2] Publishing the swf in megaswf.com will exploit a persistent xss-vulnerability and run your JS code.

Full code-example that can be used on a frame as actionscript :

import flash.net.URLRequest;
var alert:URLRequest = new URLRequest("javascript:alert('xss')");
navigateToURL(alert, "_self");


Reference(s) :
http://megaswf.com/serve/1471214


Security Risk:
==============
The security risk of the persistant cross site scripting vulnerability is estimated as medium(+).


Credits & Authors:
==================
Vulnerability Research Laboratory -  Sebastian Lüdtke  (yak0n)


Disclaimer & Information:
=========================
The information provided in this advisory is provided as it is without any warranty. Vulnerability-Lab disclaims all warranties, 
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may not apply. We do not approve or encourage anybody to break any vendor licenses, policies, deface websites, hack into databases 
or trade with fraud/stolen material.

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