Barracuda Cloud Series - Filter Bypass Vulnerability

Type vulnerlab
Reporter Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri ( []
Modified 2015-01-19T00:00:00


                                            Document Title:
Barracuda Cloud Series - Filter Bypass Vulnerability

References (Source):

Barracuda Networks Security ID (BNSEC): 731

Release Date:

Vulnerability Laboratory ID (VL-ID):

Common Vulnerability Scoring System:

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:

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

Exploitation Technique:

Severity Level:

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.

<iframe src=a>%20%20%20%20\"><iframe src= onload=alert("VL") <

<script language=JavaScript>m='%3Ciframe%20src%3Da%3E%2520%2520%2520%2520%5C%22%3E%3Ciframe%20src%3Dhttp%3A//';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 ( []

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.

Domains:   	-			       		-
Contact: 	- 	       		-
Section:	-		       	-
Social:!/vuln_lab 		- 	       		-
Feeds:	-   		-
Programs:  	-	-

Any modified copy or reproduction, including partially usages, of this file requires authorization from Vulnerability Laboratory. Permission to 
electronically redistribute this alert in its unmodified form is granted. All other rights, including the use of other media, are reserved by 
Vulnerability-Lab Research Team or its suppliers. All pictures, texts, advisories, source code, videos and other information on this website 
is trademark of vulnerability-lab team & the specific authors or managers. To record, list (feed), modify, use or edit our material contact 
( or to get a permission.

				Copyright © 2015 | Vulnerability Laboratory - [Evolution Security GmbH]™