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List:       full-disclosure
Subject:    [Full-disclosure] Skype Community - Mail Encoding Web Vulnerability #2
From:       Vulnerability Lab <research () vulnerability-lab ! com>
Date:       2012-11-26 18:04:35
Message-ID: 50B3AF33.4070508 () vulnerability-lab ! com
[Download RAW message or body]

Title:
======
Skype Community - Mail Encoding Web Vulnerability #2


Date:
=====
2012-11-21


References:
===========
http://www.vulnerability-lab.com/get_content.php?id=719


VL-ID:
=====
719


Common Vulnerability Scoring System:
====================================
4


Introduction:
=============
Skype is a proprietary voice-over-Internet Protocol service and software application originally \
created in 2003 by Swedish entrepreneur  Niklas Zennström and his Danish partner Janus Friis. \
It has been owned by Microsoft since 2011. The service allows users to communicate  with peers \
by voice, video, and instant messaging over the Internet. Phone calls may be placed to \
recipients on the traditional telephone  networks. Calls to other users within the Skype \
service are free of charge, while calls to landline telephones and mobile phones are charged  \
via a debit-based user account system. Skype has also become popular for its additional \
features, including file transfer, and videoconferencing.  Competitors include SIP and \
H.323-based services, such as Linphone, as well as the Google Talk service, Mumble and \
Hall.com.

Skype has 663 million registered users as of September 2011. The network is operated by \
Microsoft, which has its Skype division headquarters  in Luxembourg. Most of the development \
team and 44% of the overall employees of the division are situated in Tallinn and Tartu, \
Estonia.

Unlike most other VoIP services, Skype is a hybrid peer-to-peer and client–server system. It \
makes use of background processing on computers  running Skype software. Skype`s original \
proposed name (Sky Peer-to-Peer) reflects this fact. Some network administrators have banned \
Skype  on corporate, government, home, and education networks, citing reasons such as \
inappropriate usage of resources, excessive bandwidth usage,  and security concerns.

(Copy of the Vendor Homepage: http://en.wikipedia.org/wiki/Skype)


Abstract:
=========
The Vulnerability Laboratory Research Team discovered a filter & mail encoding vulnerability in \
the official Skype Community Website Application.


Report-Timeline:
================
2012-10-08:	Researcher Notification & Coordination
2012-10-10:	Vendor Notification
2012-10-12:	Vendor Response/Feedback
2012-11-18:	Vendor Fix/Patch
2012-11-21:	Public or Non-Public Disclosure


Status:
========
Published


Affected Products:
==================
Microsoft
Product: Skype Community - Lithium Forums 2012 Q3


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


Severity:
=========
High


Details:
========
A persistent input validation vulnerability is detected in the official Skype Community Website \
Application. The vulnerability is located in the update post form with the unsanitized username \
in send mails. Attackers can inject malicious persistent script code on application side of the \
skype skype community. The vulnerability is located in the filter function of the username when \
skype community is processing  to send a not parsed update mail. Remote attacker with low \
privileged application user accounts can change  the username values to malicious persistent \
script code via POST. The result in a persistent script code  inject via noreply@skype.net. \
Successful exploitation of the vulnerability result in persistent phishing  attacks, persistent \
session hijacking or mail context manipulation via persistent inject.

Vulnerable Section(s):
			[+] Skype Community - (Forums)

Vulnerable Module(s):
			[+] Notification Mail

Vulnerable Parameter(s):
			[+] Username

Affected Section(s):
			[+] Update Mail - Filter / Output Listing


Proof of Concept:
=================
The vulnerability can be exploited by remote attackers with low privileged application user \
account and with  low or medium required user inter action. For demonstration or reproduce ...

<html>
<head>
<title>Skype Support Network Subscription: 1 Update: Betreff: Skype is Hacked ! \
Win32.Trojan.Agent.Gen  schleicht sich durch die Accounts</title>
<link rel="important stylesheet" href="chrome://messagebody/skin/messageBody.css">
</head>
<body>
<table border=0 cellspacing=0 cellpadding=0 width="100%" \
class="header-part1"><tr><td><b>Betreff:  </b>Skype Support Network Subscription: 1 Update: \
Betreff: Skype is Hacked ! Win32.Trojan.Agent.Gen schleicht sich  durch die \
Accounts</td></tr><tr><td><b>Von: </b>Community Mailer \
<noreply@skype.net></td></tr><tr><td><b>Datum:  </b>06.10.2012 16:04</td></tr></table><table \
border=0 cellspacing=0 cellpadding=0 width="100%" class="header-part2"><tr> <td><b>An: \
</b>rm01x <admin@vulnerability-lab.com></td></tr></table><br> <html>
	<head>
		<title>
			Skype Support Network Subscription: 1  Update: Betreff: Skype is Hacked ! 
Win32.Trojan.Agent.Gen schleicht sich durch die Accounts		</title>
		<style type="text/css">
			body, td { font: 10pt Arial, Helvetica; }
		</style>
	</head>
	<body class="lia-body email-template">
		<div class="lia-content subscription subscription-digest">
			<div class="email-header">
				<h2 class="email-greeting">
					Hello <[[PERSISTENT INJECTED SCRIPT CODE AS USERNAME!]]>,
				</h2>
				<p class="email-totals">
					You have 1  update for your Skype Support Network Subscriptions.
				</p>
							</div><!-- end email-header -->

			<div class="email-main email-subscriptions">
									<hr />
					<div class="email-subscription">
<h3>Subscription to Thema: <a \
href="http://community.skype.com/t5/Skype-f%C3%BCr-Windows/Skype-is-Hacked-Win32- \
Trojan-Agent-Gen-schleicht-sich-durch-die/td-p/1086370">Skype is Hacked ! \
Win32.Trojan.Agent.Gen schleicht sich  durch die Accounts</a> (1 Update)</h3>
<div class="email-subscription-notifications">
<div class="email-subscription-notification">

There was a new Antworten.<br>

<table class="notification-metadata" border=0 cellspacing=0 cellpadding=2>
<tr><td>Subject:  </td><td> <a \
href="http://community.skype.com/t5/Skype-f%C3%BCr-Windows/Skype-is-Hacked-Win32- \
Trojan-Agent-Gen-schleicht-sich-durch-die/m-p/1101468#M6531">Betreff: Skype is Hacked ! \
Win32.Trojan.Agent.Gen schleicht  sich durch die Accounts</a></td></tr>
<tr><td>Author:</td><td>Methu (New Member)</td></tr>
<tr><td>Date:</td><td>06-10-2012 16:04</td></tr>
</table>
								
<p class="email-notification-body-separate">
<a href="http://community.skype.com/t5/Skype-f%C3%BCr-Windows/Skype-is-Hacked-Win32-Trojan-Agent-Gen-
 schleicht-sich-durch-die/m-p/1101468#M6531">View</a>
</p>
</div><!-- end email-subscription-notification -->
</div><!-- end email-subscription-notifications -->
</div><!-- end email-subscription -->
</div><!-- end email-subscriptions -->
			<hr />
			<div class="email-footer">
				<p class="manage-normal">
					To manage your subscriptions or to change your subscription options,
					click <a href="http://community.skype.com/skypec/user_subscriptions">here</a>.
				</p>
				<p class="manage-alternate">
					If this link doesn't work: 
					<ol>
						<li>Log on to Skype Support Network.</li>
						<li>Click <b>My Profile</b>.</li>
						<li>Click the <b>Subscriptions & Bookmarks</b> tab. </li>
						<li>Change your settings and click <b>Save Changes</b>. </li>
					</ol>
				</p>
				<p class="manage-thanks">Thanks for being a Skype Support Network member.</p>
				<p class="manage-team">
					<i>Your Skype Support Network Team</i>
				</p>
				<font size=-1>
					<p class="manage-sent-to">
						Skype Support Network sent this message to admin@vulnerability-lab.com.
					</p>
<p class="manage-unsubscribe">
Did not request this email yourself? Click <a \
href="http://community.skype.com/t5/user/RemoveUserEmailPage/user-id \
/1915382/mail-message-tracking/H7YSNPPZVRU0CL">this link</a> to permanently prevent your email \
address being used on  our community (NB: You won't be able to use the address yourself in the \
future).  
			</p>
				</font>
			</div><!-- end email-subscriptions-manage -->
		</div><!-- end lithium-content -->
	</body>
</html>
</body>
</html>


Solution:
=========
The vulnerability can be patched by parsing the context with the lithium api request of the \
community application formular.


Risk:
=====
The security risk of the filter & mail encoding vulnerability is estimated as \
medium(+)|(-)high.


Credits:
========
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (bkm@vulnerability-lab.com)


Disclaimer:
===========
The information provided in this advisory is provided as it is without any warranty. \
Vulnerability-Lab disclaims all warranties,  either expressed or implied, including the \
warranties of merchantability and capability for a particular purpose. Vulnerability- Lab or \
its suppliers are not liable in any case of damage, including direct, indirect, incidental, \
consequential loss of business  profits or special damages, even if Vulnerability-Lab or its \
suppliers have been advised of the possibility of such damages. Some  states do not allow the \
exclusion or limitation of liability for consequential or incidental damages so the foregoing \
limitation  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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    				   	Copyright  © 2012 | Vulnerability Laboratory



-- 
VULNERABILITY RESEARCH LABORATORY
LABORATORY RESEARCH TEAM
CONTACT: research@vulnerability-lab.com


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