Lab: File path traversal, validation of start of path

PRACTITIONER

This lab contains a path traversal vulnerability in the display of product images.

The application transmits the full file path via a request parameter, and validates that the supplied path starts with the expected folder.

To solve the lab, retrieve the contents of the /etc/passwd file.

Solution

  1. Use Burp Suite to intercept and modify a request that fetches a product image.
  2. Modify the filename parameter, giving it the value:

    /var/www/images/../../../etc/passwd
  3. Observe that the response contains the contents of the /etc/passwd file.

Community solutions

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Intigriti
Michael Sommer