weird_text - HackCon 2019

Thu 22 Aug. 2019, 16:30 BST - Fri 23 Aug. 2019, 16:30 BST

Summary: A decoding challenge that requires some knowledge of esoteric programming languages.

With this challenge we are given a txt file with a seemingly random assortment of symbols as seen in the image below.




If this is your first time seeing this it may look like a load of random nonsense but it is in fact the most well known esoteric programming language, brainfuck! So all we need to do to decode this is find ourselves a brainfuck interpreter! Here is the link to the one I used, now let's see what we get when we run it through the interpreter!




And what do you know, more nonsense! This one isn't as easily identifiable as brainfuck as there are much more different types of characters being used making it seem heaps more random. Luckily after a bit of searching I was able to identify this esoteric language as Malbolge, and again as we did with the brainfuck code we run this Malbolge code through another interpreter!
Now let's see what we get back this time.




Hmph. Looks like it translates into hex code, let's decode this to ascii and see what we get! If you're following along I recommend this site!




Hey looks like the flag is there! But it's backwards? Maybe we were supposed to compile this hex somehow? Either way it's no trouble as with a simple python trick we can reverse the string to give us the valid flag, like so!