We go to the URL and intercept the request in Burp.
Initial request:
First, we modify the User-Agent request and change Mozilla -> Picobrowser:
We get the phrase “I don’t trust users visiting from another site.” This suggests that the website checks not only the User-Agent header, but also the Referer header . This means that the site also checks which site the request came from and whether it came from an “official” site. We add:
The phrase “Sorry, this site only worked in 2018” suggests that the site can be “tricked” by adding a Date header and specifying the date in the format
Date: Wed, 01 Jun 2022 08:00:00 GMT (About Date header) We are adding, but with 2018:
The phrase “I don’t trust users who can be tracked” means that the server detects certain headers or parameters of your request that allow it to be tracked. Let’s remove Cookie and add DNT: 1 (do not track):
Now we need to specify that we are from Sweden. Let’s add header X-Forwarded-For: 194.71.1.1 (with Swedish IP):
But don’t forget to change language from uk-UA,uk; to sv-SE,sv;
picoCTF{http_h34d3rs_v3ry_c0Ol_much_w0w_0da16bb2}