Types of Malware

Malware - Simply, malware is "bad" software. Malware includes any software that harms a system, data, or processes/applications. Many of the malware categories overlap like trojans and spyware.

Trojan - In a simple summary, trojans hide in applications to get into a user's system or they act as a program themselves. This malware does not replicate. For illustration, a hacker could make a password manager that will supposedly store the users passwords and enter them in for the user. Instead, the username, site, and password combinations are sent to the trojan maker instead of storing the data - this would be a spyware trojan. Additionally, the hacker can hack a real application that handles sensitive data. The data would then be sent to the hacker. Trojans not only take private data, but they may sneak in ads or destroy the system.

Spyware - This malware gathers a user's private data (financial info, passwords, usernames, etc.) and sends it to the spyware maker or other entity that will use the information. Spyware can be trojans and some trojans can be spyware.

Adware - Software that displays ads is considered adware. Not all adware is bad. For instance, Flashget is a freeware Windows application that is adware. The program is safe to use. The ads just fund the development of Flashget. Because most Linux developers make applications open-source, not very many Linux adware programs can be found.

Worms - A computer worm is a replicating program that spreads to other computers. Most rely on networks for transportation. Many readers may ask "What is the difference between a virus and worm?". Simple, viruses attach to programs and worms are standalone software. Viruses come on programs that users download and worms break in through the network. As a general rule, if a user brought it into the system, then it is a virus, else if the malware got in without user intervention, then it is a worm.

Viruses - Computer viruses are replicating code that spread by hiding inside of infected applications and installers.

Zombies - Computer zombies are computers that are controlled by a malicious hacker, trojan, or computer virus to complete malicious tasks.

Riskware - Software with unintended malicious potential. These applications can be used by malware to cause a lot of damage. Because this software is not malware, but can be dangerous is called riskware.

Scareware - Malware that scares users into downloading malicious software or paying money for the fix is scareware. For illustration, scareware may pop up a message that says something like "Your data will be deleted unless you pay $100.". Scareware may also come in the form of a free virus scan over the Internet. This virus scan does not scan the system, but pretends to do so. The scanner will say it found a virus. The scanner then asks the user to pay money to have the virus removed. In summary, scareware scares computer users into paying money or installing malware to protect themselves against a nonexistent threat.

Ransomware - Ransomware is similar to scareware. Ransomware locks the computer and files and will not lift the restrictions until the user pays a ransom. Ransomware really locks the system while scareware bluffs.

Proto-Virus - Some malware is simply annoying. Malware developers might make a computer virus as a prank to bother people. Such malware does not cause damage. A well-known example is the Cookie Monster virus (http://en.wikipedia.org/wiki/Cookie_Monster_(computer_program)) that simply makes messages saying it wants a cookie.