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Microsoft Yammer Cross Site Scripting

Microsoft Yammer Cross Site Scripting
Posted Dec 13, 2013
Authored by Ateeq ur Rehman Khan, Vulnerability Laboratory | Site vulnerability-lab.com

Microsoft Yammer suffered from multiple cross site scripting vulnerabilities.

tags | exploit, vulnerability, xss
SHA-256 | ffa493a522284668c4144c5b4d98ae3cb0b8e667db062ea350d352b646b98b01

Microsoft Yammer Cross Site Scripting

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Document Title:
Microsoft Yammer - Persistent Profile Vulnerabilities

References (Source):

MSRC ID: 14808

Release Date:

Vulnerability Laboratory ID (VL-ID):

Common Vulnerability Scoring System:

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:

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

Exploitation Technique:

Severity Level:

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 ...

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

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:

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)

Disclaimer & Information:
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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