Virology 101 (UNIX System Virus)

There is nothing mysterious about computer viruses. A working, but easily observable, virus can be written in a few lines of code. Although particular virus attacks may be guarded against, no general defense within one domain of reference is possible; viruses are a natural consequence of stored-program computation. Like other hazards of technology, their threat may be mitigated by cautious behavior and community sanctions. I. The principle I intend to demonsftate a simple, yet realistic, computer virus for people who may be curious but who have not been motivated to dabble in this shady field. Nothing here will edify folks bent on mischief. The example is made for clarity; it makes no malign effort to hide in obscure recesses of a computer system. It has been expressed in a highly accessible language-the shell language of UNIX systems. Thus it may be understood without resort to "microscope and tweezers." [Eichen & Rochlis 1988] For good cause, it has not been tested. Ostensibly as a public service, but probably more to establish priestly mystery, writers about viruses usually omit the details.