The state of shared web hosting security is grim. Customers need to demand better. It's not an unsolvable problem. Hosting companies have just mostly been competing with a race to bottom-barrel pricing. When you're paying $5 a month for hosting, three things will usually suffer: Stability, Security, and Support.

I maintain that shared hosting, by and large, is a disaster waiting to happen. And the funny thing is, you can get a solid VPS on the cheap now. The host I recently switched to, Digital Ocean, has a plan that only costs $5/month. Five dollars a month will get you a box, a virtual machine that's properly walled off from other customers, with 512MB of memory, 20GB of space on an SSD and a higher monthly data transfer quota than the vast majority of sites would use in a year. RamNode has similarly attractive pricing.

All it takes is a tiny amount of Linux knowledge and you can install an nginx+php+mysql stack and be up and running in a couple hours.

There's really no reason for someone to subject themselves to the horrors of shared hosting.