The 15 Most Influential People in Security Today - 15. Stefan Esser, Hardened PHP Project
If there's a security hole in PHP, chances are it was found by Stefan Esser, an open-source security specialist. Esser's advisories about flaws in Linux, NetBSD, Samba, Ethereal, CVS, Subversion, MySQL and PHP are legendary. He is also known as the first hacker to completely break the DRM (digital rights management) scheme of the Microsoft Xbox with software-only exploits. His "Month of PHP Bugs" project thoroughly exposed the insecure nature of the widely deployed PHP language and forced a rethink about security in the open-source world.