Facebook Bug Bounty #16 (Studio) - Persistent Vulnerability Dec 18 2014 12:48PM
Vulnerability Lab (research vulnerability-lab com)
Document Title:
Facebook Bug Bounty #16 (Studio) - Persistent Vulnerability

References (Source):

Facebook Security ID: 219162244

Release Date:

Vulnerability Laboratory ID (VL-ID):

Common Vulnerability Scoring System:

Product & Service Introduction:
Facebook is an online social networking service, whose name stems from the colloquial name for the book given to students
at the start of the academic year by some university administrations in the United States to help students get to know
each other. It was founded in February 2004 by Mark Zuckerberg with his college roommates and fellow Harvard University
students Eduardo Saverin, Andrew McCollum, Dustin Moskovitz and Chris Hughes. The website`s membership was initially limited
by the founders to Harvard students, but was expanded to other colleges in the Boston area, the Ivy League, and Stanford University.
It gradually added support for students at various other universities before opening to high school students, and eventually to anyone
aged 13 and over. Facebook now allows any users who declare themselves to be at least 13 years old to become registered users of the site.

Users must register before using the site, after which they may create a personal profile, add other users as friends, and exchange messages,
including automatic notifications when they update their profile. Additionally, users may join common-interest user groups, organized by workplace,
school or college, or other characteristics, and categorize their friends into lists such as `People From Work` or `Close Friends`. As of
September 2012, Facebook has over one billion active users, of which 8.7% are fake. According to a May 2011 Consumer Reports survey, there are
7.5 million children under 13 with accounts and 5 million under 10, violating the site`s terms of service.

In May 2005, Accel partners invested $12.7 million in Facebook, and Jim Breyer added $1 million of his own money to the pot. A January 2009
Compete.com study ranked Facebook as the most used social networking service by worldwide monthly active users. Entertainment Weekly included the
site on its end-of-the-decade `best-of` list, saying, `How on earth did we stalk our exes, remember our co-workers` birthdays, bug our friends,
and play a rousing game of Scrabulous before Facebook?` Facebook eventually filed for an initial public offering on February 1, 2012, and was
headquartered in Menlo Park, California. Facebook Inc. began selling stock to the public and trading on the NASDAQ on May 18, 2012. Based on its
2012 income of USD 5.1 Billion, Facebook joined the Fortune 500 list for the first time, being placed at position of 462 on the list published in 2013.

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

Abstract Advisory Information:
An independent Vulnerability Laboratory Researcher discovered a persistent input validation web vulnerability in the official Facebook Studio web-application.

Vulnerability Disclosure Timeline:
2014-12-10: Public Disclosure (Vulnerability Laboratory)

Discovery Status:

Affected Product(s):
Product: Studio Service - Web Application 2014 Q4

Exploitation Technique:

Severity Level:

Technical Details & Description:
A persistent input validation web vulnerability has been discovered in the official Facebook Studio online-service web-application.
The vulnerability allows remote attackers to inject malicious script codes on the application-side to compromise the online-service application.

The vulnerability is located in the dashboard module of the facebook studio service. Remote attackers are able to inject own script codes to the mobile
client of facebook. After the inject of the payload the attacker can visit the dashboard service to execute the script codes. The vulnerability was
disclosed during a pentest of the htmlentities on fb mobile client to the facebook studio service. The attack vector of the issue is persistent and
the request method to inject is POST.

The security risk of the persistent vulnerability is estimated as medium with a cvss (common vulnerability scoring system) count of 3.5.
Exploitation of the persistent security vulnerability requires a low privileged web-application user account and medium user interaction.
Successful exploitation of the vulnerability results in persistent phishing attacks, persistent session hijacking attacks, persistent
external redirect to malicious sources and application-side manipulation of affected or connected module context.

Request Method(s):
[+] POST

Vulnerable Module(s): Input
[+] https://m.facebook.com/editprofile.php?type=contact&edit=website&refid=1

Affected Module(s): Output
[+] https://www.facebook-studio.com/dashboard#_=_

Proof of Concept (PoC):
Exploiting this bug is a first order injection in facebook mobile (m.facebook.com for firefox) that will result xss in the studio.

Manual steps to reproduce the vulnerability ...

1. Open the following fb mobile webpage https://m.facebook.com/editprofile.php?type=contact&edit=website&refid=1
Note: (using Firefox)
2. Then remove all the URLs you have (if you have any)
3. Add for example "https://somethinag.com/"onmouseover="alert(31337);­." (without the quotes)
4. After that surf to https://www.facebook-studio.com/dashboard#_=_ and you will have your stored XSS.
Note: Facebook didnt use htmlentity to the url when processing to add it in the database. When-ever being rendered, it wont be a second-order-injection.
5. Successful reproduce of the vulnerability!

The full payload you need to add to your website is ...

PoC: https://url-source.com/"style="font-size:900px;"onmouseover="alert(31337
Note: The full payload you need to add to your website is listed above.

Solution - Fix & Patch:
Issue has already been patched by the facebook developer team during the participate in the official bug bounty program.

Security Risk:
The security risk of the persistent input validation web vulnerability in the facebook studio website is estimated as medium. (CVSS 3.5)

Credits & Authors:
Paulos Yibelo

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