• The VM needed for this challenge can be downloaded here.
• You’ll need Kali Linux.
• You’ll need a separate Ubuntu machine you control for demonstration purposes in the first part of the lab.

First Steps:

• You will not have the login credentials to the machine.

• Before you power it on, go to the machine settings and give the network adapter a custom MAC address.

  • This way you will be able to locate it with the arp-scan utility within Kali.
  • Don’t use the MAC address I have below. Everyone in the class needs something different.
    • Manually randomize the MAC Address you give your machine!

  

Once you have started the CTF machine, launch a root shell in Kali and do the following:

• use the *arp-scan* utility to scan the entire subnet and report back on MAC addresses that are present.
  • Your Kali Linux machine must be on the same subnet as the CTF machine.
• Use grep to filter for the MAC address that you gave the CTF Machine.
• NOTE: I only grep for the OUI of the MAC address. You should grep for the entire MAC Address!
  • Use all 6 Hex characters in your grep

Start with an Nmap:

• It will turn up a web server on port 80 this time

Here’s the index.html with a brief explanation of what to expect:

This challenge highlights CORS (Cross-Origin Resource Sharing.) Through the attack demonstrated here, you'll learn why CORS policies are essential for the integrity and security of web applications and how they prevent unwanted cross-origin requests.

Although we don’t exploit a CORS misconfiguration, understanding how to read CORS-specific headers is essential for the final exploit.

Before attacking the site, let’s work with CORS in a controlled environment to get a solid understanding of the mechanisms involved.

Do the following: