What is a zombie?

The word "zombie" has three possible definitions in the context of computing:

• An insecure computer that's compromised by a worm or Trojan horse and used in either distributed denial of service (DDoS) attacks or spamming sessions. Compromised computers usually have a bot installed that listens to commands on IRC channels; when a command is given, all the compromised computers begin the DDoS attack or spam propagation. This protects the author of the spam/DDoS attack, since those attacks can only be traced back to the compromised computer, not the author.

  This usage derives from the typical meaning of "zombie" as an animated corpse with no independent will that mindlessly follows the commands of a controller. "Zombied" computers, under the control of some remote cracker or hacker, execute DDoS or spamming sessions with no input from the legitimate owner/user.

• A child process that has finished its task but hasn't been terminated by its parent process. In other words, it's part of a program (or maybe even an entire program) that is hanging or locked up.
  
  
• A very old, very out-of-date web site, usually abandoned by the owner. This is archaic usage; such sites are more typically referred to as "orphans" or "ghost sites".

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