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Advent of CTF challenge 1

Today, I started with the Advent of CTF challenges. In this blogpost I will give a write-up on how I managed to solve the challenge.

  1. open the challenge on https://01.adventofctf.com/
    It will come up with a screen where Santa’s password should be entered.

2. Let’s see what the source code tells us, by pressing F12

Hmmmm, the string looks indeed encoded. Let’s see if we can decode this string.

3. Copy the encoded string, and open https://gchq.github.io/CyberChef/
4. Paste de encoded string into the inputfield of CyberChef and you will see the magic wand appearing

By clicking the magic wand, it tells me that the encoded string is BASE64, and should produce the following output when decoded:

advent_of_ctf_is_here

Could this be the password from Santa to enter the challenge? Let’s find out!

5. Copy the code, and paste it into the Santa’s password box, and click Submit.

And there it is! The first flag of Advent of CTF.

Credits for the creator of this event! @credmp