Stefan Esser is best known in the security community as the PHP security guy. Since he became a PHP core developer in 2002 he devoted a lot of time to PHP and PHP application vulnerability research. However in his early days he released lots of advisories about vulnerabilities in software like CVS, Samba, OpenBSD or Internet Explorer. In 2003 he was the first to boot linux directly from the harddisk of an unmodified XBOX through a buffer overflow in the XBOX font loader. In 2004 he founded the Hardened-PHP Project to develop a more secure version of PHP, known as Hardened-PHP, which evolved into the Suhosin PHP Security System in 2006. Since 2007 he works as head of research and development for the german web application company SektionEins GmbH that he co- founded.