We found this strange website. (http://18.104.22.168/)
For this challenge we only get a website with a sum on it.
112 + 386 + 712 + 1398 + 8771 + 11982 + 15397 + 23984 = 51037
This doesn’t give us much information. How about we look at the headers.
This was the challenge which scored us the last couple of points and put us on the second place. We thought a write up would be nice. This challenge gave us some headache, and if you see the final solution it looks so easy, but it was a long way to get there.
The server involved was the 192.168.0.5. After a nmap scan we noticed the server was listening on port 21/tcp, or ftp. The service info also gives us the first clue of the challenge, it was a port knocking exercise.
This is how we solved it.