Crack the Gate 1 | PicoCTF Challenge

Category: Web Exploitation

Difficulty: Easy

Challenge description: We're in the middle of an investigation. One of our persons of interest, ctf player, is believed to be hiding sensitive data inside a restricted web portal. We've uncovered the email address he uses to log in: ctf-player@cylabacademy.org. Unfortunately, we don't know the password, and the usual guessing techniques haven't worked. But something feels off... it's almost like the developer left a secret way in. Can you figure it out?

Hints:

Developers sometimes leave notes in the code; but not always in plain text.
A common trick is to rotate each letter by 13 positions in the alphabet.

Walkthrough:

First, we enter the email that was provided in the description and try the word "password" as a password to see what happens when we click the login button.

as we can see we got an alert message that says: "Invalid credentials".

Now, let's inspect the HTML page of this website and check if there's any hidden comments or other clues.

Intreseting, we found a comment in the HTML page that contains a string of seemingly random characters that appears to be encoded which in fact IS.

This comment was encoded using ROT13 — ROT13 is a simple letter substitution cipher that replaces each letter with the 13th letter after it in the Latin alphabet.

So now lets decrypt it on rot13.com and then we get "NOTE: Jack — temporary bypass: use header "X-Dev-Access: yes", which is basically an HTTP header that we could use in Burp Suite.

After getting on Burp Suite and clicking on login to send a POST request to our HTTP history, we send this POST request to our repeater so we can modify it and add the header that we just got to our request headers.

Here we go after adding our HTTP header as we can see we got the flag and we can submit it to PicoCTF.

Note

if you're attempting this challenge, i recommend trying it on your own before reading the solution.

Follow me for more Cybersecurity writeups.

vo1dbyt3 - Medium Read writing from vo1dbyt3 on Medium. Cybersecurity Student | Web Exploitation * Penetration Testing

If you noticed any issue with the explanation or solution, please try letting me know in the comments.

Have a nice one.