Robert Slade: Chapter 3 - Fred Cohen

No historical overview of viral programs can be complete without mention of the work of Fred Cohen.

Hi Fred. (Just kidding.)

In the early 1980s, Fred Cohen did extensive theoretical research, as well as setting up and performing numerous practical experiments, regarding viral type programs. His dissertation was presented in 1986 as part of the requirements for a doctorate in electrical engineering from the University of Southern California. This work is foundational, and any serious student of viral programs disregards it at his own risk.

(Dr. Cohen's writings are available for purchase from: ASP Press, PO Box 81270, Pittsburgh, PA 15217, USA.)

Dr. Cohen's definition of a computer virus as "a program that can 'infect' other programs by modifying them to include a ... version of itself" is generally accepted as a standard. On occasion it presents problems with the acceptance of, say, boot sector viral programs and entities such as the Internet/UNIX/Morris worm. However, his work did experimentally demonstrate and theoretically prove many vital issues.

I cannot, in one column, describe the sum total of his work. In my opinion, the most important aspects are the demonstration of the universality of risk, and the limitations of protection. His practical work proved the technical feasibility of a viral attack in any computer system environment. (This feat was achieved within a closed environment and could not, by its nature, have predicted the social and psychological factors which have contributed to the pandemic spread of viral programs "in the wild".) Equally important, his theoretical study proved that the "universal" detection of a virus is undecidable. Although monitoring and analytical programs have a place in the antiviral pantheon, this fact means that they, and, in fact, all other antiviral software, can never give 100% guaranteed protection. Without this early work, it is likely that some toilers in the antiviral vineyards would still be pursuing that elusive grail.