how do you know whether your system has become one of the living dead?
Talk about a scary phenomenon! Through a virus or worm, a criminal takes over your PC, which behaves normally until it receives instructions over the Internet to mass-mail spam, take down a company's network as part of a Distributed Denial of Service (DDoS) attack, or log your keystrokes to gain access to your bank account. When it's done, your system reverts to acting like a normal PC.