Computer virus

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History
Academic work

The first academic work on the theory of computer viruses (although the term "computer virus" was not invented at that time) was done in 1949 by John von Neumann who held lectures at the University of Illinois about the "Theory and Organization of Complicated Automata". The work of von Neumann was later published as the "Theory of self-reproducing automata".[5] In his essay von Neumann postulated that a computer program could reproduce.

In 1972 Veith Risak published his article "Selbstreproduzierende Automaten mit minimaler Informationsübertragung" (Self-reproducing automata with minimal information exchange).[6] The article describes a fully functional virus written in assembler language for a SIEMENS 4004/35 computer system.

In 1980 Jürgen Kraus wrote his diplom thesis "Selbstreproduktion bei Programmen" (Self-reproduction of programs) at the University of Dortmund.[7] In his work Kraus postulated that computer programs can behave in a way similar to biological viruses.

In 1984 Fred Cohen from the University of Southern California wrote his paper "Computer Viruses - Theory and Experiments".[8] It was the first paper to explicitly call a self-reproducing program a "virus", a term introduced by Cohen's mentor Leonard Adleman.


Operating system reinstallation

Reinstalling the operating system is another approach to virus removal. It involves either reformatting the computer's hard drive and installing the OS and all programs from original media, or restoring the entire partition with a clean backup image. User data can be restored by booting from a Live CD, or putting the hard drive into another computer and booting from its operating system with great care not to infect the second computer by executing any infected programs on the original drive; and once the system has been restored precautions must be taken to avoid reinfection from a restored executable file.

These methods are simple to do, may be faster than disinfecting a computer, and are guaranteed to remove any malware. If the operating system and programs must be reinstalled from scratch, the time and effort to reinstall, reconfigure, and restore user preferences must be taken into account.
See also