1.4 KiB
+++ author = "Maik de Kruif" title = "The Source" subtitle = "Challenge 1 - AdventOfCTF" date = 2020-12-02T17:27:25+01:00 description = "A writeup for challenge 1 of AdventOfCTF." cover = "img/writeups/adventofctf/2020/3f12301d8715a1371d2d776d25ea6ab6.png" tags = [ "AdventOfCTF", "challenge", "ctf", "hacking", "writeup", "web", ] categories = [ "ctf", "writeups", "hacking", ] aliases = [ "challenge_1" ] +++
- Points: 100
Description
All starts should be easy
Visit https://01.adventofctf.com to start the challenge.
Solution
When opening the page, we're asked for Santa's password. Unfortunately, we don't know the password. Don't stop there though, mayby someone has hidden it in the source html.
Let's open the source by pressing Ctrl + U and take a look at it. Near the bottom we find the following comment:
<!-- This is an odd encoded thing right? YWR2ZW50X29mX2N0Zl9pc19oZXJl -->
This looks like a base64 encoded string so let's use the program base64 with the -d decode flag to decode the text.
> echo "YWR2ZW50X29mX2N0Zl9pc19oZXJl" | base64 -d
advent_of_ctf_is_here
We get some plain text. If we enter it as Santa's password on the challenge page, it gives us the flag: NOVI{L3T_7H3_M0NTH_0F_FUN_START}.
This flag can then be submitted for the challenge.