Worms and Trojan horses

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*Worms and Trojan horses

Besides viruses, there are other similar programs that are often confused with viruses. A worm is a program that “worms” its way through either the computer’s memory or the computer disk and may alter bits of data that accesses. A virus may be considered a worm and worms that replicate themselves can be thought of as viruses. All viruses attach themselves to other programs to hide from the user while worms are usually thought of as stand alone programs.

Programs which hide themselves to penetrate a computer system are generally known as Trojan Horses. The Trojan horse is named after the large wooden horse in Homer’s Iliad in which the Greeks hid in order to invade Troy. Trojan horses in computers behave in very much the same way. A program, often a virus, will attach itself to a seemingly innocent program. Game and graphics are by far the most popular. Users who make a copies of this program will find out later that their computer systems have now contracted a computer virus. The Trojan horse does not replicate itself but the virus it contains make copies of itself within the system.

The last type of program discussed here is the logic/time bomb. This program is often carried in a Trojan horse and may include a virus or be part of a virus. A logic/time bomb is activated or triggered after or during a certain event. An example is the Israeli virus which causes programs to disappear on Friday the 13th. Other logic/time bomb may be activated after several executions. It is very difficult to detect a logic/time bomb because the system will work correctly for some time until it reaches the active stage when it is too late to protect the file that may be altered or destroy.