20-10-2012, 04:41 PM
LOGIC BOMBS
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ABSTRACT
What is it?
A logic bomb is a program which has deliberately been written or modified to produce results when certain conditions are met that are unexpected and unauthorized by legitimate users or owners of the software.
Logic bombs may reside within stand-alone programs or they may be part of worms (programs that hide their existence and spread copies of themselves within a computer system and through networks) or viruses (programs or code segments which hide within other programs and spread copies of themselves).
An example of a logic bomb is any program that mysteriously stops working three months after, say, its programmer's name has disappeared from the corporate salary database.
Case study:
In 1985, a disgruntled computer security officer at an insurance brokerage firm in Texas set up a complex series of Job Control Language (JCL) and RPG (an old programming language) programs described later as " tripwires and time bombs. " For example, a routine data retrieval function was modified to cause the IBM System/38 midrange computer to power down. Another routine was programmed to erase random sections of main memory, change its own name, and reset itself to execute a month later.
In 1992, a computer programmer was fined $5,000 for leaving a logic bomb at General Dynamics. His intention was to return after his program had erased critical data and get paid lots of money to fix the problem.