UBNT Bug Bounty #3 - Persistent Filename Vulnerability

[Vulnerability Lab <research@xxxxxxxxxxxxxxxxxxxxx>]

Document Title:
===============
UBNT Bug Bounty #3 - Persistent Filename Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1467

Video: http://www.vulnerability-lab.com/get_content.php?id=1468


Release Date:
=============
2015-08-11


Vulnerability Laboratory ID (VL-ID):
====================================
1467


Common Vulnerability Scoring System:
====================================
4.2


Product & Service Introduction:
===============================
Ubiquiti Networks is an American technology company started in 2005. Based in 
San Jose, California they are a manufacturer of 
wireless products whose primary focus is on under-served and emerging markets.

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


Abstract Advisory Information:
==============================
The Vulnerability Laboratory Core Research Team discovered an application-side 
input validation web vulnerability in the official Ubiquiti Networks Community 
online service web-application.


Vulnerability Disclosure Timeline:
==================================
2015-03-17: Researcher Notification & Coordination (Hadji Samir)
2015-03-18: Vendor Notification (Ubnt Security Team - Bug Bounty Program)
2015-04-12: Vendor Response/Feedback (Ubnt Security Team - Bug Bounty Program)
2015-07-09: Vendor Fix/Patch (Ubnt Developer Team)
2015-08-11: Public Disclosure (Vulnerability Laboratory)


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


Affected Product(s):
====================
Ubiquiti Network
Product: Ubnt Community - Web Application (Online Service) 2015 Q2


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


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


Technical Details & Description:
================================
An application-side web vulnerability has been discovered in the official 
Ubiquiti Networks Community online service web-application.
The vulnerability allows an remote attacker to inject own script code to the 
application-side of the affected application module.

The web vulnerability is located in the `filename` value of the `gallery page 
album upload` module. Remote attackers are able to inject own files 
with malicious `filename` value in the `album upload` POST method request to 
compromise the ubnt web-application. Remote attackers are also able 
to exploit the filename issue in combination with persistent injected script 
codes to execute different malicious attack requests. The attack vector 
is located on the application-side of the ubnt service and the request method 
to inject is POST. 

The security risk of the application-side web vulnerability is estimated as 
medium with a cvss (common vulnerability scoring system) count of 4.2. 
Exploitation of the application-side validation web vulnerability requires no 
user interaction and only a low privileged web-application user account. 
Successful exploitation of the security vulnerability results in the ubnt 
community web-application compromise.

Request Method(s):
                                [+] [POST]

Vulnerable Module(s):
                                [+] gallerypage (upload)

Vulnerable Parameter(s):
                                [+] filename (Album)

Affected Module(s):
                                [+] confirmationpage


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

Manual steps to reproduce the vulnerability ...
1. Open link http://community.ubnt.com/t5/media/gallerypage
2. Click add images
3. Upload image with name "><img src="x" onerror=alert(document.cookie)>.png
4. Click selact an album and save
5. Post comment
6. Click selete the comment you will redirect to 
http://community.ubnt.com/t5/action/confirmationpage
7. Now you will see the alert with the document cookies context!

PoC Video: http://www.vulnerability-lab.com/get_content.php?id=1468


Reference(s):
http://community.ubnt.com/
http://community.ubnt.com/t5/media/gallerypage
http://community.ubnt.com/t5/action/confirmationpage


Solution - Fix & Patch:
=======================
The vulnerability can be patched by a secure parse and encode of the vulnerable 
filename value in the album add module.
Restrict the input and encode the filename to prevent further script code 
injection attack that runs through the application-side.
Disallow special chars and implement a secure exception to prevent the 
execution itself.


Security Risk:
==============
The security risk of the application-side album filename input validation web 
vulnerability is estimated as medium. (CVSS 4.2)


Credits & Authors:
==================
Vulnerability Laboratory [Research Team] - Hadji Samir [samir@xxxxxxxxxxxxxxxxx]


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