1.5 KiB
+++ author = "Maik de Kruif" title = "Teaser" subtitle = "Challenge 0 - AdventOfCTF" date = 2020-12-02T17:20:28+01:00 description = "A writeup for challenge 0 of AdventOfCTF." cover = "img/writeups/adventofctf/2020/f90b2bf3f08ee628c09505ff309018ed.png" tags = [ "AdventOfCTF", "challenge", "ctf", "hacking", "writeup", "web", ] categories = [ "ctf", "writeups", "hacking", ] aliases = [ "challenge_0" ] +++
- Points: 1
Description
Do you remember the flag in the teaser website?
Solution
Sadly, the teaser website isn't online anymore. If only someone kept an archive of the internet. This is where the Wayback Machine on archive.org comes in handy.
So, let's use the Wayback Machine to get the teaser page. https://web.archive.org/web/20201112020839/https://adventofctf.com/
When we take a look at the source html of the page we find the following comment:
<!-- Ceasar worked on this you know. Tk9WSXtIRVlfMVNfVGgxU19AX0ZsYTk/fQ== -->
It looks like some encoded string. If you've been doing CTFs for a while you'll probably recognize it's encoded in base64. We can use the program base64 to decode this string.
> echo "Tk9WSXtIRVlfMVNfVGgxU19AX0ZsYTk/fQ==" | base64 -d
NOVI{HEY_1S_Th1S_@_Fla9?}
We found the flag! It's NOVI{HEY_1S_Th1S_@_Fla9?}.
This flag can then be submitted for the challenge.