So, loading favicon.ico via a redirect-type parameter: <img onload="alert('logged in to fb')" onerror="alert('not logged in to fb')" src="https://www.faceb

So, loading favicon.ico via a redirect-type parameter: <img onload="alert('logged in to fb')" onerror="alert('not logged in to fb')" src="https://www.facebook.com/login.php?next=https%3A%2F%2Fwww.facebook.com%2Ffavicon.ico">