A Simple CTF Challenge that expects user to see Client Side Login Algorithm, Path Traversal and Command Injection.

Language Used = Python3
Modules/Packages used:

• os
• flask

Install the dependencies:

pip install -r requirements.txt

• Add Part 1 of the Flag in /etc/passwd (for Path Traversal)

echo part_1_of_the_flag >> /etc/passwd

• Add Part 2 of the Flag in Environment Variables (for Command Injection)

export flag_part_2="part_2_of_the_flag"

• After seeing Robot on Index page, we head to /robots.txt
• There are 2 Routes listed there
  • /remote_file_access_login: Login Route
  • /parts: Gives us hints where the parts of the Flags are stored
• After going to /remote_file_access_login, we find the login logic in the JavaScript Code. We get the following Credentials for login:
  • User: kaptaan
  • Password: main_daku_ek_number_da_han
• After Login, we see list of Files
• After selecting 1 file, we get to know that it sends a get request to /getFileContent with parameter file
• Here file is vulnerable to Path Traversal and Command Injection.
• We do Path Traversal to /etc/passwd to get the First Part of the Flag.
• We do Command Injection to get the Environment Variables, which gives us the second part of the Flag.