1.	register_globals: The bad man of PHP security is register_globals, which used to default to "on" in older releases of PHP but has since been changed to default to "off". It exports all user input as global variables. Check this setting and disable it -- no buts, no exceptions. Just do it! This setting is possibly responsible for more PHP security flaws than any other single cause. If you're on a shared host, and they won't let you disable register_globals, get a new host!