Simple Web

Overview

Overall difficulty for me (From 1-10 stars): ★☆☆☆☆☆☆☆☆☆

Background

Find the flag

In this challenge, we can download a file:

┌[siunam♥earth]-(~/ctf/VU-Cyberthon-2023/Web/Simple-Web)-[2023.02.25|15:02:55(HKT)]
└> file Task-www.zip 
Task-www.zip: Zip archive data, at least v2.0 to extract, compression method=deflate
┌[siunam♥earth]-(~/ctf/VU-Cyberthon-2023/Web/Simple-Web)-[2023.02.25|15:02:57(HKT)]
└> unzip Task-www.zip              
Archive:  Task-www.zip
  inflating: Task-www-index.html

Task-www-index.html:

<html>
    <head>
        <meta http-equiv="refresh" WWW-Authenticate="--[----->+<]>---.-[--->+<]>+++.---[->+++<]>.+++.+++++++++++++.++.------------.+++++++.-." sop="WWW-Authenticate in esoteric programming language" content="1;url=https://www.cyberthon.lt/">
    </head>
    <body>
        <h1>Redirecting in 1 seconds...</h1>
    </body>
</html>

In the WWW-Authenticate attribute, we can see that it’s value is an esoteric programming language called “Brainfuck”.

We can decode that via an online tool:

Flag: VU{cyberthon}

Conclusion

What we’ve learned:

“Brainfuck” Esoteric Programming Language