There has been considerable interest in computer viruses since they first appeared in 1981, and especially in the past few years as they have reached epidemic numbers in many personal computer environments. Viruses have been written about as a security problem, as a social problem, and as a possible means of performing useful tasks in a distributed computing environment. However, only recently have some scientists begun to ask if computer viruses are not a form of artificial life — a self-replicating organism. Simply because computer viruses do not exist as organic molecules may not be sufficient reason to dismiss the classification of this form of “vandalware ” as a form of life. This paper begins with a description of how computer viruses operate and their history, and of the various ways computer viruses are structured. It then examines how viruses meet properties associated with life as defined by some researchers in the area of artificial life and selforganizing systems. The paper concludes with some comments directed towards the definition of artificially “alive ” systems and experimentation. 1

BIOGRAPHICAL SKETCH................................................................................. 78 ix LIST OF FIGURES Figure 1-1: Melissa time line [From the Congressional testimony of Richard Pethia]...2 Figure 2-1: Picture of the formal definition [Cohen 94]........................................6 Figure 2-2: The figure represents the two integrity states a system can have and the transitions that can occur............................................................8 Figure 3-1: An abstract model for an organ of virus or worm program....................14 Figure 3-2: The functional organs of virus and worm programs shown as grayed nodes..................................................................................17 Figure 3-3: A representation of the replication cycle for a worm program...............17 Figure 3-4: A representation of the infection cycle for a virus program...................18 Figure 3-5: Flow of installation and injection operations in a MS Word macro environment..........................................................................21 Figure 3-6: Installing in recently used files...................................................22 Figure 3-7: Updating the registry during installation........................................22 Figure 3-8: The flow chart showing a frequently used method of installation and injection in macro viruses..........................................................23 Figure 3-9: Encrypted virus code with the decryptor routine attached at the beginning..............................................................................32 Figure 3-10: The intermediate virus code obtained after the decryp...

There has been considerable interest in computer viruses since they first appeared in 1981, and especially in the past few years as they have reached epidemic numbers in many personal computer environments. Viruses have been written about as a security problem, as a social problem, and as a possible means of performing useful tasks in a distributed computing environment.