picoCTF Web Exploitation Guide

where are the robots

Name: where are the robots
Description: Can you find the robots? https://jupiter.challenges.picoctf.org/problem/56830/ (link) or http://jupiter.challenges.picoctf.org:56830
Author: zaratec/Danny
Tags: Easy, Web Exploitation, picoCTF 2019
Challenge from: picoCTF 2019
Hints:
1. What part of the website could tell you where the creator doesn't want you to look?

Theory

According to the description, to get the flag we have to find the robots. This might be referring to the Robots.txt text file, which is used by website makers to instruct web crawlers (robots taking site information to match searches) like google and other search engines what to get or not to level out traffic in your website. So let's go to this link they're giving us.

Solution

So we'll open the website:

Yeah, so let's go to robots.txt and see if there's something in there:

http://jupiter.challenges.picoctf.org:56830/robots.txt

User-agent: *
Disallow: /1bb4c.html

Huh, there's a link in here, let's go there see if there's something of interest:

http://jupiter.challenges.picoctf.org:56830/1bb4c.html

There's the flag. Now just copy it from there:

picoCTF{ca1cu1at1ng_Mach1n3s_1bb4c}

There we go! That's the flag.

I rated this level as "good"! :3