Tags: chans sposting bruteforce recon imageboard
To begin, it is immediately obvious that these are post numbers. 'install gentoo' backs this up. Post numbers that high are likely to be found on 4chan. I assumed that it would be upon the technology board which it was.
This lead to another group of of post numbers and a sha1sum hash. From the hints it should be obvious that all hashes from now on that come first will be the sha1sum of most likely a chan (fqdn = fully qualified domain name)
I guessed the most obvious choice would be to post on 8ch.net/tech/ next. I checked this by checking the sha1sum of '8ch.net'. This leads to a post of vim chan. This time there are two hashes.
At this point it becomes needed to write a program in order to try to bruteforce these hashes. This can be optimized with the hints in order to concentrate on the prefix of the tld.
Although, through combining the powers of shitposting, there are two hashes here. The first one for the website, the second one for a post.
The only related website where posts look like that would be notabug.io. Therefore, the next post is found within the comment section of notabug.io.
From here, I started to frantically note down all the chans I had knowledge of, as well as google dorking for the said tlds with keywords such as technology and imageboard. This was done injunction with a script designed to bruteforce the hash although as my computing power is somewhat limited, bruteforcing longer domain names would be somewhat of a challenge. My two methods consisted of pure bruteforce and a wordlist of all chans I knew of + google.
Eventually, I now ended up on dangeru.us/tech/, which is where the next post lies. While I could bruteforce this hash, I immediately recognize it as the hash of 4chan.org as I have seen it through the course of this challenge. However, as the board was not specified it is a case of guessing which board the post numbers were relevant to.
This leads to yet another post on /x/. It is at this point the challenge was cut short for taking too long. The original post would lead to lainchan.org/tech/, then to yet another hash that I did not work out since a shortcut was present.
In the reply to the post in question, there were relatively low post numbers and another hash. I sat back and bruteforced it while trying to think of a place where post numbers would be that low. Luckily, this one was relatively short, allowing me to get it quickly as kek.fun.
This was the final step, with the flag lying on the /wpi/ board.
[P.S its not reddit spacing its just for visual clarity]