Quick plug - I host a lot of my friends websites for them on Webfaction. I uploaded a theme from Woothemes for a friend that contained (without me knowing) an outdated version of timthumb.php. Webfaction emailed me that the plugin was outdated and automatically upgraded it to the newest one.

I've had no complaints with them and if you're worried about this sort of activity you might want to consider switching to use them as a hosting provider.