Differentiate among a virus, worm, Trojan horse, and rootkit.

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. A virus replicates itself by attaching to program files. It can then be passed from computer to computer via flash-drive, CD, DVD or downloaded program. Viruses can also conceal themselves to avoid detection. A stealth virus disguises itself by hiding in fake code sections, which it inserts within actual working code in a file.

In addition to viruses, other Malware includes worms, Trojan horse programs, and rootkits.

•A worm resides in active memory and replicates itself over a network to infect computers and devices, using up the system resources and possibly shutting down the system. It uses the networks inherent connectivity to spread throughout the network.

•A Trojan horse is a destructive program disguised as a real program, such as a screen saver. When a user runs a seemingly innocent program, a Trojan horse hiding inside can capture information, such as user names and passwords, from your computer or enable someone remotely to control your computer. Unlike viruses, Trojan horses do not replicate themselves.

•A rootkit is a program that easily can hide and allow someone to take full control of your computer from a remote location, often for nefarious purposes. They can be hidden from detection because they have instructions built into their code that tells the computer to hide the information from the user. If you have a folder that shows it is empty but you can not delete the folder, you may have a rootkit virus.