Kakegura Secret CTF Challenge Writeup

Challenge Information

• Name: Kakegura Secret
• Points: 1
• Category: Web
• Objective: Exploit a Local File Inclusion (LFI) vulnerability to retrieve the flag.

Solution

To solve the “Kakegura Secret” challenge, follow these steps:

1. Initial Exploration:

   • The website appears to be a PHP-based application.

   • Clicking on the “Flag” page does not display the flag directly.

     

2. Identifying the Vulnerability:

   • By clicking around the website, you can suspect the presence of a Local File Inclusion (LFI) vulnerability, possibly involving PHP filters.

   • The way the page renders suggests that files may be included dynamically.

     

3. Exploiting LFI with PHP Filters:

   • Use PHP filters to exploit the LFI vulnerability to read sensitive files.

   • Example payload:

     1	?page=php://filter/convert.base64-encode/resource=index.php

   • By leveraging the filter to base64 encode the content of files, retrieve the contents of important files, including the one containing the flag.

     

4. Flag Retrieval:

   • Successfully exploit the LFI to access the flag and decode it.