BetaCurve

Description

BetaCurve is a miscellaneous challenge written by more for the 2023 Texsaw CTF https://ctftime.org/event/1959. It was worth 300 points and was only solved by 5 teams. The description of the challenge is as follow:

Some strange man handed me this picture mumbling something about a map, skyrim belongs to the nords, 18.216.238.24, and getting dripped out. Can you help be decipher its meaning?

It also contained the following image.

Walkthrough

From the provided image we first see two distinct object. Dominating the image is a maze-like diagram and on the right border is a bunch of numbers.

Putting the numbers through cyberchef we can see that each decimal number represents a hexidecimal number, and that each hexidecimal number represents and ASCII letter. When we decipher the complete message we get: PORT IS 6767

Using the provided IP in the description we can nc 18.216.238.24 6767 and receive the following response.

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Congrats you found me! I've left you a maze to traverse but beware, the path is difficult and treacherous!
To assist you I've called Terrana Cliff and David Hilbert.

At the end of the path, what do you find?
Solution:

Searching Terrana Cliff we will find the the following page which looks like our large maze-like structure. Through this we know that the maze is actually a BetaMaze where each block 3x3 of the image represents a character. Using this site to decode the betamaze and get the following solution matrix.

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P A R K
Y E L P
D R I P
X B O X

If we try to enter this into the console we get the following output.

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Congrats you found me! I've left you a maze to traverse but beware, the path is difficult and treacherous!
To assist you I've called Terrana Cliff and David Hilbert.

At the end of the path, what do you find?
Solution: parkyelpdripxbox
You didn't think it'd be that easy did ya?

Dang, clearly we’re missing something. So if Terrana Cliff helped us get the Beta in BetaCurve what can David Hilbert give us? After doing some googling we can find a wikipeia page on Hilbert’s Curve, and the second order curve sure does look like it could be used in a 4x4 matrix such as what we have in the betamaze.

Solution

So if we trace over our matrix there are four orientations that it could be. To make it easy you should start at the top left corner and move right first. When we do this we get PAEYDXBRIOXPPLRK.

Inputting this into the console we get:

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Congrats you found me! I've left you a maze to traverse but beware, the path is difficult and treacherous!
To assist you I've called Terrana Cliff and David Hilbert.

At the end of the path, what do you find?
Solution: PAEYDXBRIOXPPLRK
Congratulations! The flag is: texsaw{g1v3_m3_th4t_dr1p}