- · A computer virus
is a potentially damaging computer program that affects, or infects, a computer negatively by altering the way the computer works without the user’s knowledge or permission. Once the virus infects the computer, it can spread throughout and may damage files and system software, including the operating system.
- · A worm is a program that copies itself repeatedly, for example in memory
or on a network
, using up resources and possibly shutting down the computer or network.
- · A Trojan horses (named after the Greek myth) is a program that hides within or looks like a legitimate program. A certain condition or action usually triggers the Trojan horse. Unlike a virus
or worm, a Trojan horse doesn’t replicate itself to other computers.
- · A rootkit is a program that hides in a computer and allows someone from a remote location to take full control of the computer. Once the rootkit is installed, the rootkit author can execute programs, change settings, monitor activity, and access files on the remote computer. Although rootkits can have legitimates uses, such as in law enforcement, their use in nefarious and illegal activities is growing rapidly.
