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# Barracuda Cloud Series - Filter Bypass Vulnerability

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Document Title:
===============
Barracuda Cloud Series - Filter Bypass Vulnerability (ID 731)


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=754

Barracuda Networks Security ID (BNSEC): 731


Release Date:
=============
2015-01-19


Vulnerability Laboratory ID (VL-ID):
====================================
754


Common Vulnerability Scoring System:
====================================
4.1


Abstract Advisory Information:
==============================
The Vulnerability Laboratory Research Team discovered a filter bypass vulnerability in the official Barracuda Cloud
Series Products.


Vulnerability Disclosure Timeline:
==================================
2015-01-19: Public Disclosure (Vulnerability Laboratory)


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


Affected Product(s):
====================
Barracuda Networks
Product: Cloud Control Center 2014 Q2


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


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


Technical Details & Description:
================================
A filter bypass vulnerability has been discovered in the official Barracuda Networks Cloud Series Appliance Applications
2014-Q1. The filter bypass issue allows an attacker to bypass the secure filter validation of the service to execute
malicious script codes.

The barracuda filter blocks for example standard iframes, scripts and other invalid code context: The cloud service has
a own exception-handling to parse or encode malicious injected web context. The mechanism filters the first request and
sanitizes the output in every input field.

During a pentest we injected a standard iframe to check and provoke the validation. The frame got blocked! In the next
step the attacker splits (%20%20%20) the request and injects at the end an onload frame to an external malicious source.
The second iframe with the onload alert executes the script codes after the validation encoded only the first script
code tag. The second script code tag can bypass the applicance filter mechanism and executes in the web context of
affected modules. The secure validation does not recognize a splitted request which results in client-side and
application-side script code execution in
the cloud series products.

The security risk of the filter bypass vulnerability is estimated as medium and the cvss (common vulnerability scoring
system) count is 4.1 (medium).
Exploitation of the filter bypass vulnerability requires a low privileged application user account with restricted
access and low user interaction.
Successful exploitation of the vulnerability results in session hijacking, persistent phishing, persistent external
redirects and persistent manipulation
of affected or connected module context.

Vulnerable Request Method(s):
[+] POST & GET


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

PoC:
<iframe src=a>%20%20%20%20\"><iframe src=http://vuln-lab.com onload=alert("VL") <

PoC:
<script
language=JavaScript>m='%3Ciframe%20src%3Da%3E%2520%2520%2520%2520%5C%22%3E%3Ciframe%20src%3Dhttp%3A//vuln-lab.com%20o
nload%3Dalert%28%22VL%22%29%20%3C';d=unescape(m);document.write(d);</script>


Solution - Fix & Patch:
=======================
The issue can be patched by a secure validation of the full message input body context of any input or request method
attempt. Ensure that the validaton does not only encode the first injected script code since a empty char arrives.
Filter all web context that runs through the requesting procedure and parse separatly to prevent script code injection
attacks.

Note: Barracuda Networks patched the vulnerability and acknowledged the researcher. Updates are available in Barracuda
Labs and the Customer Service.


Security Risk:
==============
The security risk of the filter bypass web vulnerability in the barracuda cloud product series is estimated as medium.
(CVSS 4.1)


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


Disclaimer & Information:
=========================
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break any vendor licenses, policies, deface websites, hack into databases or trade with fraud/stolen material.

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Copyright &#169; 2015 | Vulnerability Laboratory - [Evolution Security GmbH]

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# Iranian Exploit DataBase = http://IeDb.Ir [2015-02-12]

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