Computer Viruses and Worms Dragan Lojpur Zhu Fang Definition of Virus A virus is a small piece of software that piggybacks on real programs in order to get executed Once it’s running, it spreads by inserting copies of itself into other executable code or documents Computer Virus Timeline 1949 Theories for self-replicating programs are first developed. 1981 Apple Viruses 1, 2, and 3 are some of the first viruses “in the wild,” or in the public domain. Found on