WhatsApp: LFI Vulnerability

 

 

 

Before starting to describe the issue found on WhatsApp i want to introduce the LFI Vulnerability.

The File Inclusion vulnerability allows an attacker to include a file, usually exploiting a “dynamic file inclusion” mechanisms implemented in the target application. The vulnerability occurs due to the use of user-supplied input without proper validation.
This can lead to something as outputting the contents of the file, but depending on the severity, it can also lead to:

  • Code execution on the web server
  • Code execution on the client-side such as JavaScript which can lead to other attacks such as cross site scripting (XSS)
  • Denial of Service (DoS)
  • Sensitive Information Disclosure

Local File Inclusion (also known as LFI) is the process of including files, that are already locally present on the server, through the exploiting of vulnerable inclusion procedures implemented in the application. This vulnerability occurs, for example, when a page receives, as input, the path to the file that has to be included and this input is not properly sanitized, allowing directory traversal characters (such as dot-dot-slash) to be injected. Although most examples point to vulnerable PHP scripts, we should keep in mind that it is also common in other technologies such as JSP, ASP and others.

The vulnerable link that allows me to download the /etc/passwd file is :

http://media.whatsapp.com/directory/..%252f..%252f..%252f..%252fetc%252fpasswd

Schermata del 2014-06-05 11:31:07

and this is the content of the /etc/passwd file

aa

The bug has now been fixed.

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