Feross Aboukhadijeh developed an attack concept that exploits the fullscreen application programming interface in HTML5 in order to carry out advance phishing attacks. The HTML5 “Fullscreen API” allow web developers to display web contents in full-screen mode, that is, filling-up the display screen completely. Chad Hurley, CEO and co-founder of YouTube, was so impressed that he immediately offered him a job at YouTube. The attack depends on social engineering rather than flawed code.
Source: https://thehackernews.com/2012/10/advance-phishing-attacks-using-html5.html