A logic bomb is a program, or a part of another program, which will trigger a malicious function when specified conditions are met. Normally a logic bomb does not replicate itself and therefore logic bomb will not spread to unintended victims. Logic bombs are written and targeted against a specific victim.
A logic bomb is code which consists of two parts:
• A pay load, which is an action to perform which normally, has malicious effect.
• A trigger, a Boolean condition that is evaluated and controls when the payload is executed. The trigger can be date, the user logged in conditions, network conditions etc.