File path traversal, traversal sequences stripped with superfluous URL-decode


This lab contains a file path traversal vulnerability in the display of product images. The application blocks input containing path traversal sequences. It then performs a URL-decode of the input before using it.

Reproduction and proof of concept

  1. Use Burp Suite to intercept and modify a request that fetches a product image.

  2. Modify the filename parameter, giving it the value: ..%252f..%252f..%252fetc/passwd

  3. The response contains the contents of the /etc/passwd file:



An attacker will need to encode the payload to retrieve the contents of the /etc/passwd file