Rootkits

I've read several articles now about rootkits. If you don't know what a rootkit is, it is amalicious  trojan like program to allow an intruder to become a root user and therefore have complete administrative control over the system. From what I've read, there aren't too many rootkits out there, but the number is increasing. I decided to install and run Chkrootkit. Just run "sudo apt-get install chkrootkit". To run it, in Terminal enter " sudo chkrootkit". I came up clean, but who knows. I may not be so lucky one day.