2024 LACTF - terms-and-conditions

Overview

• 771 solves / 106 points
• author: aplet123

Description

Welcome to LA CTF 2024! All you have to do is accept the terms and conditions and you get a flag!

terms-and-conditions.chall.lac.tf

Attached

term-and-conditions.html

Analyzation

Let’s visit the site

The button, for sure, cannot be clicked by mouse. It must be “clicked” by console.

But when the console is opened, the site becomes blank and…

Look in the source code to find the reason why

let width = window.innerWidth;
let height = window.innerHeight;
setInterval(function() {
    if (window.innerHeight !== height || window.innerWidth !== width) {
        document.body.innerHTML = "<div><h1>NO CONSOLE ALLOWED</h1></div>";
        height = window.innerHeight;
        width = window.innerWidth;
    }
}, 10);

Solution

It only does that if the dimensions of the window changes after it loads.

So let’s just leave the console there and refresh, and the console is on.

Then run the js command

document.getElementById("accept").click()

The flag is

lactf{that_button_was_definitely_not_one_of_the_terms}