As I'm seeing more questions about (badly coded) web applications spawning rogue processes I wonder why people don't read their logs. Attacks require reconnaissance so keeping an eye on anything that looks like a prelude enables you to take measures. And please spend time updating when updates are released, installing apps properly (like not leaving the installation files around when docs remind you not to), hardening (any IDS, mod_security, Gotroot rulesets, mod_evasive or equivalent, PHPIDS, Suhosin,...