Logic Bomb

A logic bomb is a piece of code in a program, usually coded by its developer(s), which is normally dormant but is designed to activate when certain external conditions are met and to cause some kind of damage. The damage can be anything doable by a program - deletion of information, leaking of information, blocking of access, providing unauthorized access and so on. The malicious action is not the whole purpose of the program; the latter usually performs some kind of desired action. And the logic bomb is programmed at the time when the program has been developed; it is not the result of external infection or any other kind of manipulation.