Barracuda Networks Firewall 6.1.5 - Filter Bypass & Persistent Vulnerabilities

Type securityvulns
Reporter Securityvulns
Modified 2014-07-28T00:00:00


Document Title:

Barracuda Networks Firewall 6.1.5 - Filter Bypass & Persistent Vulnerabilities

References (Source):

Barracuda Networks Security ID (BNSEC): BNSEC-2067


View Video:

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: )

Abstract Advisory Information:

The Vulnerability Laboratory Research Team discovered a filter bypass and multiple persistent input validation web vulnerabilities in the Barracuda Web Firewall appliance web-application.

Vulnerability Disclosure Timeline:

2013-09-04: Researcher Notification & Coordination (Benjamin Kunz Mejri) 2013-09-05: Vendor Notification (Barracuda Networks Security Team - Bug Bounty Program) 2014-04-02: Vendor Response/Feedback (Barracuda Networks Security Team - Bug Bounty Program) 2014-07-15: Vendor Fix/Patch (Barracuda Networks Developer Team) [Coordinated Disclosure] 2014-07-24: 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:

Multiple persistent input validation web vulnerabilities has been discovered in the Barracuda Networks Web Firewall X300 (v6.1.5) Appliance Web Application. The validation web vulnerability allows remote attackers or local low privileged application user accounts to inject (persistent) own malicious script codes on application-side of the vulnerable module.

The vulnerability is located in the firewall menu when processing to create a custom user object with manipulated create user expression group credentials. Remote attackers can inject script codes to the `Login Name` & `Group Match pattern text` input fields. After the inject the attacker can save the input via add (POST Method) to execute the persistent code in the edit listing.

During the first add (inject) in the edit formular the remote attacker is also able to add the input via `add to the second selection` listing to execute the persistent code in both listing values of the bottom page. Remote attackers are able to add the persistent injected context to the main custom user objects module in the predefined user objects listing. The attack vector is persistent and the request method is POST.

The security risk of the persistent input validation web vulnerabilities are estimated as medium with a cvss (common vulnerability scoring system) count of 3.9. Exploitation of the 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 web module context.

Request Method(s): [+] POST

Vulnerable Application(s): [+] Firewall (WAF) Appliance Application (X300Vx v6.1.0.016 & 6.1.5.x )

Vulnerable Module(s): [+] Firewall > User Objects > Custom User Objects > Create User Object > Create User Expression

Vulnerable Parameter(s): [+] login name [+] pattern - Group Match

Affected Module(s): [+] Firewall > User Objects > Custom User Objects > Predefined User Objects Listing [+] Firewall > User Objects > Custom User Objects > Create User Object > Create User Expression (Group)

Proof of Concept (PoC):

The persistent input validation web vulnerabilities can be exploited by remote attackers with low privileged application user account and low user interaction. For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue.

Manual steps to reproduce the vulnerability:

  1. Login with the user account to the barracuda networks web firewall appliance application
  2. After the login open the firewall and switch to the User Objects > Custom User Objects > Create User Object module
  3. Start creating via user expression a group
  4. Include a random name for the main mask, and add your script code as payload to the login name and pattern (group match) input fields
  5. Click the checkbox for the group match and click the add button to save the input
  6. The code executes in the add box context itself and the group match or pattern values listing (bottom) [3 times]
  7. Now, the attacker is also able to add the already injected persistent context to the main menu listing by a click of the add button to save at the bottom
  8. The script code execution occurs when processing to watch the firewall_user_objects module index item listing Note: The vulnerable values are login name (name) and pattner
  9. Successful reproduce of the persistent web vulnerabilities!

PoC: firewall_user_objects - index listing

<tr style="" class="config_module_tr display oddRow" id="config_module_rowfw_predefined_user_objects_1_1" onmouseout="if (!this.isSelected) {;}" onmouseover="if (!this.isSelected) {;'#a1a1a1';}"> <td style="width: 150px;"> </td> <td style="width: 200px;"> </td> <td style="width:150px"><[PERSISTENT INJECTED SCRIPT CODE!]></td> <td style="width:250px"><[PERSISTENT INJECTED SCRIPT CODE!]></td> <td style="width: 116px;"> </td> </tr>

Reference(s): https://firewall.ptest.localhost:6299/cgi-mod/index.cgi ?auth_type=Local&et=1378340277&locale=en_US&password=b9bc2762a9868729613918058ac1fb56&user=guest&primary_tab=FIREWALL&secondary_tab=firewall_user_objects

PoC: Create User Object > Create User Expression - Listing

<tr class="config_module_tr" id="config_module_row_4"> <td valign="top" width="15"> </td> <td valign="top" width="100">Group Match</td>​​​​​

<td valign="top" width="400"><table class="config_module IT" frame="box" id="group_match_table" rules="none" summary="Box" cellpadding="0" cellspacing="0"><tbody><tr bgcolor="#cccccc"><td style="text-align:center;"><b>Pattern</b></td> <td style="text-align:center;" width="20"><b></b></td></tr><tr><td><input class="" autocomplete="off" id="group_match_pattern" name="group_match_pattern" size="30" type="text"></td><td width="20"><input class="new_button" id="+" name="+" onclick="add_group_match_pattern()" value="+" type="button"></td></tr> <tr class="pattern"><td>a%20>"<[PERSISTENT INJECTED SCRIPT CODE!]"></iframe></td><td><input class="new_button" value="-" name="0" type="button"></td>​​​​​</tr></tbody></table><input id="pattern_group_match:yes" name="pattern_group_match" value="yes" type="checkbox"> <label for="pattern_group_match:yes" style="display:inline">All Group Patterns must match</label></td>

<td valign="top" width="120"><div id="helpbox"><b class="outlinetop">

<b class="outline1"></b> <b class="outline2"></b> <b class="outline3"></b>

<b class="outline4"></b></b> <div id="contents"><div>List of user group patterns according to efficient authentication method.<br> If the check box is cleared, only one list item may match. <b>Default</b>: Off</div></div> <b class="outlinebottom"><b class="outline4"></b><b class="outline3"></b><b class="outline2"></b><b class="outline1"></b></b> </div></td></tr>

... && Add

<tbody><tr bgcolor="#cccccc"><td style="text-align:center;" width="100">​​​​​<b>Name</b></td><td style="text-align:center;" width="100"><b>Group Match</b></td><td style="text-align:center;" width="50"><b></b></td></tr> <tr class="pattern"> <td>a%20>"<[PERSISTENT INJECTED SCRIPT CODE!]"></iframe></td><td>a%20>"​​​​​<[PERSISTENT INJECTED SCRIPT CODE!]"> </iframe></td><td><img style="cursor:pointer;" name="0" src="/images/edit.png"><input name="0" src="/images/del.png" type="image"></td></tr></tbody>

--- Request Session Logs ---

Status: 200[OK] POST https://firewall.ptest.localhost:6299/cgi-mod/index.cgi Load Flags[LOAD_BYPASS_CACHE LOAD_BACKGROUND ] Content Size[-1] Mime Type[text/plain]

Request Headers: Host[firewall.ptest.localhost:6299] 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:6299/cgi-mod/index.cgi? password=4b3c71efe69b776c7af9c2a0e44d8da6&et=1378331067&content_only=1&primary_tab=FIREWALL&new_secondary_tab= firewall_user_objects&auth_type=Local&user=guest&locale=en_US&secondary_tab=add_firewall_user_object&ispopup=1& parent_name=add_firewall_user_object&popup_width=530&popup_height=500] Content-Length[237] Connection[keep-alive] Pragma[no-cache] Cache-Control[no-cache] Post Data: ajax_action[check_param_ajax_single] name[group_match_pattern] value[(PERSISTENT INJECTED SCRIPT CODE!)<] user[guest] password[2f156d447f2d3972ab50762e5b0f581d] et[1378331075] locale[en_US] auth_type[Local] realm[]

Response Headers: Server[BarracudaFirewallHTTP 4.0] Date[Wed, 04 Sep 2013 21:26:16 GMT] Content-Type[text/plain; charset=utf-8] Transfer-Encoding[chunked] Connection[keep-alive]

GET https://firewall.ptest.localhost:6299/cgi-mod/[PERSISTENT INJECTED SCRIPT CODE!]< Load Flags[LOAD_DOCUMENT_URI ] Content Size[1789] Mime Type[text/html] Request Headers: Host[] User-Agent[Mozilla/5.0 (Windows NT 6.1; WOW64; rv:23.0) Gecko/20100101 Firefox/23.0] Accept[text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8] Accept-Language[en-US,en;q=0.5] Accept-Encoding[gzip, deflate] DNT[1] Referer[https://firewall.ptest.localhost:6299/cgi-mod/index.cgipassword=4b3c71efe69b776c7af9c2a0e44d8da6&et=1378331067&content_only= 1&primary_tab=FIREWALL&new_secondary_tab=firewall_user_objects&auth_type=Local&user=guest&locale=en_US&secondary_tab= add_firewall_user_object&ispopup=1&parent_name=add_firewall_user_object&popup_width=530&popup_height=500] Connection[keep-alive] Response Headers: Server[BarracudaFirewallHTTP 4.0] Date[Wed, 04 Sep 2013 21:26:16 GMT] Content-Type[text/html] Content-Length[1789] Connection[keep-alive]

Reference(s): https://firewall.ptest.localhost:6299/cgi-mod/index.cgi? password=a1524626db9371fd7c3db09cc21836aa&et=1378331929&content_only=1&primary_tab=FIREWALL&new_secondary_tab=firewall_user_objects &auth_type=Local&user=guest&locale=en_US&secondary_tab=add_firewall_user_object&ispopup=1&parent_name=add_firewall_user_object& popup_width=530&popup_height=500

https://firewall.ptest.localhost:6299/cgi-mod/index.cgi? auth_type=Local&et=1378340277&locale=en_US&password=b9bc2762a9868729613918058ac1fb56&user=guest&primary_tab=FIREWALL& secondary_tab=firewall_user_objects

Solution - Fix & Patch:

The vulnerability can be patched by a secure parse of the match group pattern and login name input fields in the firewall_user_objects module. Encode also the vulnerable output item listing of the pattern text and login name in the main- and edit firewall_user_objects listing to prevent further persistent script code injection attacks via POST method request. Implement the regular alos the regular formular validation of barracuda the the item list module.

Barracuda Networks: Appliances > Advanced > Firmware Updates (automatic) page or use the regular customer panel

Security Risk:

The security risk of the persistent input validation web vulnerabilities in connection with the input filter bypass are estimated as medium.

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.

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