The term ``computer
virus'' was formally defined by Fred Cohen in 1983, while he performed academic
experiments on a Digital Equipment Corporation VAX system. Viruses are
classified as being one of two types: research or ``in the wild.'' A research
virus is one that has been written for research or study purposes and has
received almost no distribution to the public. On the other hand, viruses which
have been seen with any regularity are termed ``in the wild.'' The first
computer viruses were developed in the early 1980s. The first viruses found in
the wild were Apple II viruses, such as Elk Cloner, which was reported in 1981 [Den90]. Viruses have
now been found on the following platforms:
- Apple II
- IBM PC
- Viruses exploit weaknesses in operating system controls and human patterns of system use/misuse.
- Destructive viruses are more likely to be eradicated.
- An innovative virus may have a larger initial window to propagate before it is discovered and the ``average'' anti-viral product is modified to detect or eradicate it.
- Menyebarkan virus memerlukan populasi besar sistem homogen dan tukar menukar software dieksekusi.