Definition:A Logic Bomb is a threat vector that is designed to invade and likely do damage to a computer or computer network infrastructure. Executable code, malicious or otherwise, is delivered to an information system and embedded in an application or on storage media. The unauthorized program awaits for a pre-determined condition to occur (i.e. a particular date) and then it runs. When doing so the payload is delivered and it performs whatever function it was coded to do much in the same way as a Trojan horse or a Virus. Establishing a base line of code, however, couple with careful firewall settings might be of help.
Its Relevance: Nefarious code that lies dormant until being activated is a significant threat. Theoretically, it is possible for such a program to be rooted in a system and for asset owners to be totally unaware. A defense, based upon known signatures for malicious code, would be useless.