Course

In this section, we delve into the intricacies of exploiting file upload functionalities in web applications to achieve code execution. By understanding how web applications handle file uploads, especially in PHP environments, we can manipulate file names and extensions to upload malicious scripts. We start with a basic PHP web shell that executes commands from user input, demonstrating how an attacker can gain control over a server by simply uploading a crafted file.

The lab walks through a source code review of a vulnerable file upload mechanism, highlighting key issues such as the lack of file type validation and the potential for overwriting files. By analyzing how the application processes uploaded files and stores them in the webroot, we uncover critical vulnerabilities that allow attackers to execute arbitrary code. This hands-on approach equips you with the knowledge to identify and exploit similar weaknesses in real-world scenarios.