Document Title:
===============
Microsoft Yammer - Persistent Profile Vulnerabilities


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=978

MSRC ID: 14808


Release Date:
=============
2013-12-12


Vulnerability Laboratory ID (VL-ID):
====================================
976


Common Vulnerability Scoring System:
====================================
4.9


Product & Service Introduction:
===============================
Yammer, Inc. is a freemium enterprise social network service that was launched in 2008 and sold to Microsoft in 2012. Yammer 
is used for private communication within organizations or between organizational members and pre-designated groups, making it 
an example of enterprise social  software. It originally launched as an enterprise microblogging service and now has applications 
on several different operating systems and devices. Access to a Yammer network is determined by a user`s Internet domain, so 
only those with appropriate email addresses may join their respective networks.

Yammer is a secure, private social network for your company. Yammer empowers employees to be more productive and successful by 
enabling them to collaborate easily, make smarter decisions faster, and self-organize into teams to take on any business challenge. 
It is a new way of working that naturally drives business alignment and agility, reduces cycle times, engages employees and improves 
relationships with customers and partners.

Pioneered Enterprise Social Networking when we launched in 2008 Among the fastest growing enterprise software companies in history, 
exceeding over four million users in just three years. Raised $142 million in venture funding from top tier firms Used by more 
than 200,000+ companies worldwide

Built social from the ground up with ‘Facebook DNA’: Facebook’s Founding President, Sean Parker serves on Yammer’s Board of Directors 
Yammer and Facebook share the same first investor, Peter Thiel; backed by Social+Capital Partnership – a fund established by former 
Facebook Vice President, Chamath Palihapitiya. More than 80 percent of the Fortune 500® are using Yammer. Leading organizations 
including Ford, Nationwide, 7-Eleven, Orbitz Worldwide, Rakuten, and Telefonica O2 have adopted Yammer.

Vendor Homepage:   http://www.microsoft.com
Product Website:   https://www.yammer.com


Abstract Advisory Information:
==============================
The Vulnerability Laboratory Research Team has discovered multiple persistent validation vulnerabilities in the Microsoft Yammer Social Network.


Vulnerability Disclosure Timeline:
==================================
2013-06-14: Researcher Notification & Coordination (Ateeq ur Rehman Khan)
2013-06-16: Vendor Notification (MSRC- Security Response Center Team)
2013-12-11: Vendor Response/Feedback (MSRC- Security Response Center Team)
2013-12-11: Vendor Fix/Patch (Microsoft - Developer Team)
2013-12-12: Public Disclosure (Vulnerability Laboratory)


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


Affected Product(s):
====================
Microsoft Corporation
Product: Yammer - Social Network Application 2013 Q2


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


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


Technical Details & Description:
================================
Microsoft Yammer Social Network Service seems to be vulnerable to multiple persistent script code injection web vulnerabilities. 
The exploitation of these vulnerabilities require a low or medium user interaction. Interesting enough, the exploits get triggered 
when the Yammer Desktop Application users interact with the Yammer Social Network Website. 

To conduct the POC tests, the researcher created a valid network on the Yammer Social Network website, registered 2 user accounts 
and also downloaded and installed the Yammer Desktop Application, Latest build. Upon further testing, it was initially noticed that 
basic security checks are in place on Yammer website and malicious requests are being blocked / filtered in almost every input field 
however I was still able to find atleast two different fields in two separate modules of the Yammer website which are both vulnerable 
to persistent script code injection flaws. 

The first vulnerable field is [department_name] under the User Edit Profile Section in My Home Network. An attacker can inject 
malicious script code into this particular field and wait for victims / unaware users to view the attacker profile using their 
Yammer Desktop Application Software.

The second vulnerable field is network[message_prompt] in Admin / Design and Configuration Module in External Networks. An attacker 
can inject malicious script code in the vulnerable field and wait for victims / unaware users to hover their mouse on over the Message 
Window for this particular exploit to get triggered.

The first bug initially discovered on the Yammer website was a self XSS which exists in the preview feature (when a user hovers the 
mouse over a profile name, a short preview window appears). All fields inside the preview window are editable and input sanatization 
is not being performed properly and hence are vulnerable to code injection. This gave the researcher much hope in conducting further 
in depth tests to analyze the application behaviour and find more vulnerabilities. As Self XSS is not considered as a security hazard, 
I have only provided references to it in the POC Video provided along with this advisory for your review.

The Yammer desktop application seems to be quite vulnerable. Using the app, the researcher was also able to find another Self XSS in 
the Topics feature. Reference is available in the POC Video provided along with this advisory. These sort of vulnerabilities can 
result in multiple attack vectors on the client end which may eventually result in complete compromise of the end user system.  

The security risk of the persistent web vulnerabilities are estimated as medium to high with a cvss (common vulnerability scoring system) count of 4.9(+)|(-)5.0.

Successful exploitation of the vulnerability may result in malicious script code being executed in the victims browser or the Yammer 
Desktop Application resulting in script code injection, persistent phishing, Client side redirects and similar attack vectors.


Vulnerable Service(s):
                      [+] Microsoft Yammer Social Network 
Vulnerable Application(s):
                      [+] Yammer Desktop Application - Latest Build - Q2 2013

Bug #1

Vulnerable Network(s):
                      [+] My Home Network
Vulnerable Section(s):
                      [+] Edit User Profile
vulnerable Field(s):
                      [+] [department_name]

Bug #2

Vulnerable Network(s):
                      [+] External Networks
Vulnerable Section(s):
                      [+] Admin - Design and Configuration 
vulnerable Field(s):
                      [+] network[message_prompt]


Proof of Concept (PoC):
=======================
The persistent input validation web vulnerabilities can be exploited by remote attackers with low privileged web-application 
user account and low user interaction. For security demonstration or to reproduce the vulnerability follow the provided steps 
and information below.

Note: The attack scenario in this case of both perspective would look like the following ...

Attacker:
---------
An attacker compromises a user profile, edits it and injects malicious script code within the vulnerable fields.  

Victim:
-------
The exploit gets triggered as soon as another Yammer Desktop Application user accesses the  network and views the Attacker Profile. 



Proof of Concept: Bug #1

You need 2 valid user accounts to do these POC's. In this case, the vulnerability can be exploited by low privilege application 
user account with low required user interaction. For demonstration or reproduce ...


Attack Scenerio:
----------------
1. Log into your Yammer profile with a valid user account. 
2. Goto User Profile and click on "EDIT PROFILE"
3. On the next page, from the menu on your Left, Click on "Profile"
4. Enter the Payload in the input field called "Department"
5. Save the External Network and log out.

Victim Scenerio:
----------------
1. Log into Yammer using the Desktop Application Software and your Second User Account
2. Goto "My Networks"
3. You should now see an Adobe AIR Popup window saying "/Vulnerable/" proving the existence of this vulnerability.




Proof of Concept: Bug #2

To produce this POC an attacker needs an admin user account. In case if no external networks are created, an attacker needs 
to create a new external network or edit an existing one in case if one exists already. 

Attack Scenerio:
----------------
1. Log into your Yammer account, the one with admin priviledges. 
2. Goto "My Networks" and Click on any existing External Networks (in this case the researcher had already created an external network)
3. On the next page, Click on "Admin" and then choose "Design and Configuration"
4. Enter the Payload in the input field called "Message Prompt"
5. Save the profile and log out.

Victim Scenerio:
----------------
1. Log into Yammer using the Desktop Application Software and your Second User Account
2. From the Top Left menu, Choose the External Network (The one you created with attacker profile)
3. After Logging in to the external network, hover your mouse on the Message Prompt with the injected Payload.
3. You should now see an Adobe AIR Popup window saying "/Vulnerable/" proving the existence of this vulnerability.


POC Payload:
A%20/><SCRIPT>alert(/Vulnerable/)</SCRIPT>



Bug #1

<th><label for="meta_user_users_attributes_0_department_name">Department</label>:</th>
<td><input class="wider" id="meta_user_users_attributes_0_department_name" maxlength="255" name="meta_user[users_attributes][0][department_name]" 
size="255" type="text" value="<H1>Alsj</H1>">AjlsfasnA%20/><SCRIPT>alert(/Vulnerable/)</SCRIPT>" /></td>
<input id="meta_user_users_attributes_0_id" name="meta_user[users_attributes][0][id]" type="hidden" value="1501443222" />      </tr>


Bug #2

<label for="network_name">Message Prompt:</label>
<input class="super-wide" id="new_message_prompt" maxlength="62" name="network[message_prompt]" size="62" type="text" 
value="A%20/><SCRIPT>alert(/Vulnerable/)</SCRIPT>" />


Solution - Fix & Patch:
=======================
Proper input sanitization should be performed in the application source code on both, website and the desktop application end in order to 
filter all malicious script code tags to mitigate any further risks associated with these vulnerabilities. 


Security Risk:
==============
The security risk of this persistent script code inject web vulnerabilities are estimated as medium(+)|(-)high.


Credits & Authors:
==================
[Vulnerability Laboratory] (Core Research Team) - Ateeq ur Rehman Khan (ateeq@evolution-sec.com)


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