Document Title: =============== NodeBB v0.8.2 - Client Side Cross Site Web Vulnerability References (Source): ==================== http://www.vulnerability-lab.com/get_content.php?id=1600 Release Date: ============= 2015-09-24 Vulnerability Laboratory ID (VL-ID): ==================================== 1607 Common Vulnerability Scoring System: ==================================== 3.4 Product & Service Introduction: =============================== NodeBB is a next-generation discussion platform that utilizes web sockets for instant interactions and real-time notifications. NodeBB forums have many modern features out of the box such as social network integration and streaming discussions. NodeBB is an open source project which can be forked on GitHub. (Copy of Vendor page https://docs.nodebb.org/en/latest/ & https://github.com/NodeBB/NodeBB/) Abstract Advisory Information: ============================== An independent vulnerability laboratory researcher discovered a client-side vulnerability in the offical NodeBB v0.8.2 forum web-application. Vulnerability Disclosure Timeline: ================================== 2015-09-24: Public Disclosure (Vulnerability Laboratory) Discovery Status: ================= Published Affected Product(s): ==================== NodeBB v0.8.2 Exploitation Technique: ======================= Remote Severity Level: =============== Medium Technical Details & Description: ================================ A non-persistent input validation web vulnerability has been discovered in the offical NodeBB v0.8.2 forum web-application. The security vulnerability allows remote attackers to manipulate client-side application to browser requests to compromise user session data. The vulnerability is located in the `url` values of the `outgoing` module. Remote attackers are able to inject malicious script codes to client-side browser to application requests. Remote attackers are able to prepare special crafted weblinks to execute client-side script code that compromises the src/controllers/index.js GET data. The execution of the script code occurs in the src/controllers/index.js module. The attack vector of the vulnerability is located on the client-side of the web-application and the request method to inject or execute the code is GET. The security risk of the non-persistent cross site vulnerability is estimated as medium with a cvss (common vulnerability scoring system) count of 3.4. Exploitation of the non-persistent cross site scripting web vulnerability requires no privilege web application user account but low or medium user interaction. Successful exploitation of the vulnerability results in session hijacking, non-persistent phishing, non-persistent external redirects, non-persistent load of malicious script codes or non-persistent web module context manipulation. Request Method(s): [+] GET Vulnerable Module(s): [+] outgoing Vulnerable Parameter(s): [+] url Affected Module(s): [+] src/controllers/index.js Proof of Concept (PoC): ======================= The security vulnerability can be exploited by remote attackers without privilege web-application user account and with low or medium user interaction. For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue. Ubuntu 14.04 (Firefox 39.0) Vulnerable is GET parameter --url-- in outgoing controller (src/controllers/index.js) PoC: http://www.[website].com/outgoing?url=<script>alert("CSXSS")</script> http://www.[website].com/outgoing?url=<script>alert(document.cookie)</script> Solution - Fix & Patch: ======================= The vulnerability can be patched by a secure parse and encode of the url value parameter in the outgoing module GET method request. Restrict the input and disallow special chars. Filter the input to prevent further client-side cross site scripting attacks. Security Risk: ============== The security risk of the client-side cross site scripting vulnerability is estimated as medium. (CVSS 3.4) Credits & Authors: ================== Mikica Ivosevic Disclaimer & Information: ========================= The information provided in this advisory is provided as it is without any warranty. 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