y lie dormant until triggered by some event. The Friday the 13th virus and Michelangelo viruses both fell into this category ("Technologies" n.p.).
A worm is an independent program that reproduces by copying itself from one computer to another, most often over a network. As with a virus, a worm compounds the damage it does by spreading rapidly from one site to another. Unlike a virus, a worm typically does not modify other programs and usually does not destroy data. Its effect is not insignificant, however, as it harnesses increasingly large amounts of resources (through maintaining and replicating itself) and by eventually bringing those resources to the point where they can no longer support the machine or the network ("Technologies" n.p.).
A bomb is a specific type of Trojan horse designed to release a virus, a worm or some other type of system attack. It can be an independent program, or a piece of code planted by a system developer or programmer. A bomb works by triggering some kind of unauthorized action when a particular time, date or condition occurs. There are typically two types of bombs: time and logic. A bomb that's set to go off on a particular date or after some period of time has gone by is a time bomb. A bomb that is set to go off when a particular event occurs is a logic bomb. Logic bombs are usually programmed to go off at key moments after installation, such as if the customer fails to pay a bill or tries to make an illegal copy ("Technologies" n.p.).
A trap door (or back door) is a mechanism that is built into a system by its designer. The function of a trap door is to give the designer a way back into the system that circumvents normal system protection. A logic bomb explodes in someone else's system; a trap door gives the original designer a secret route into the software (and provided the basis for the movie War Games). Sometimes programmers leave trap doors in a program to allow them to tes...