picoCTF WriteUp – Where are the robots

Hello Everyone,

I hope you are doing well.

Please note that, this CTF competition is over so I have rights to post the writeup publicly according to the policy.

I hope that you have tried all the possible ways to solve the challenge and you are here because you have still not found the solution.

Flag Format: picoCTF{FLAG}

Challenge Details:

Hints: What part of the website could tell you where the creator doesn’t want you to look?

Solution:

From the challenge name itself we are getting hint that we need to look into robots.txt file.

So, visit https://jupiter.challenges.picoctf.org/problem/36474/

and append the URL with robots.txt

Now the final URL becomes, https://jupiter.challenges.picoctf.org/problem/36474/robots.txt

Here, we can see

User-agent: *
Disallow: /477ce.html

Now append /477ce.html to our first URL.

So the URL looks something like this.

https://jupiter.challenges.picoctf.org/problem/36474/477ce.html

after visiting this URL, you’ll get the flag.

Flag: picoCTF{ca1cu1at1ng_Mach1n3s_477ce}

I hope that you have enjoyed the writeup and learned something new today, Please let me know if there are any concerns.

Thank You