Course

In this lab, you will learn about a PHP code injection vulnerability that exploits the `usort` function in conjunction with `create_function`. Developers often use `usort` to dynamically generate sorting functions based on user input. If the input is not adequately filtered and validated, it can lead to code execution vulnerabilities. By injecting specific payloads, we can manipulate the sorting function to execute arbitrary code on the server.

The lab demonstrates how to close the dynamically generated function properly and inject code without breaking the existing structure. This kind of vulnerability was notably present in PHPMyAdmin (CVE-2008-4096), highlighting the importance of input validation and filtering in web applications.