Ann, a software developer, has installed some code to reactivate her account one week after her account has
been disabled. Which of the following is this an example of? (Choose two.)
This is an example of both a logic bomb and a backdoor. The logic bomb is configured to ‘go off’ or activate
one week after her account has been disabled. The reactivated account will provide a backdoor into the
A logic bomb is a piece of code intentionally inserted into a software system that will set off a malicious function
when specified conditions are met. For example, a programmer may hide a piece of code that starts deleting
files should they ever be terminated from the company.
Software that is inherently malicious, such as viruses and worms, often contain logic bombs that execute a
certain payload at a pre-defined time or when some other condition is met. This technique can be used by a
virus or worm to gain momentum and spread before being noticed. Some viruses attack their host systems on
specific dates, such as Friday the 13th or April Fool’s Day. Trojans that activate on certain dates are often
called “time bombs”.
To be considered a logic bomb, the payload should be unwanted and unknown to the user of the software. As
an example, trial programs with code that disables certain functionality after a set time are not normally
regarded as logic bombs.
A backdoor in a computer system (or cryptosystem or algorithm) is a method of bypassing normal
authentication, securing unauthorized remote access to a computer, obtaining access to plaintext, and so on,
while attempting to remain undetected. The backdoor may take the form of an installed program (e.g., Back
Orifice) or may subvert the system through a rootkit.
A backdoor in a login system might take the form of a hard coded user and password combination which gives
access to the system.