File path traversal, traversal sequences stripped non-recursively

Description

This lab contains a file path traversal vulnerability in the display of product images. The application strips path traversal sequences from the user-supplied filename before using it.

Reproduction and proof of concept

Use Burp Suite to intercept and modify a request that fetches a product image.
Modify the filename parameter, giving it the value: ....//....//....//etc/passwd
The response contains the contents of the /etc/passwd file:

Traversal

Exploitability

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