This tip was found at http://aymanh.com/tips-to-secure-linux-workstation.

An old school attack on Linux systems is called a fork bomb. There is demonstration code at the fore-mentioned website, but essentially, it is a command that will spawn an unending number of processes, eventually killing the system.

Jeff pointed me to an article, supposedly breaking news, that described a "new" "web 2.0" threat, trojans using XML feeds as command and control, and using social networking sites, or other "web 2.0" sites like MySpace to store stolen information.

I was running version 4.1.1 of the free version of VNC software and have never had any problems, until about half an hour ago. VNC activated (the icon turned black) and someone started using my computer. I was able to disconnect my internet connection before anything was done.