This quiz tests your knowledge of five of the most common kinds of malware, the software you don't want on your computer: Trojan, worm, virus, spyware, and adware. Keep in mind that there are at least seven other kinds of malware we know about.

The answers are located at the end of the quiz.

1. Which of the following is most likely to make your computer stop working?

a. Trojan

b. Worm

c. Virus

d. Spyware

e. Adware

2. Which of the following is not a stand-alone program?

a. Trojan

b. Worm

c. Virus

d. Spyware

e. Adware

3. Which of the following is most likely to send spam emails from your computer?

a. Trojan

b. Worm

c. Virus

d. Spyware

e. Adware

4. Which of the following is lest likely to be detected with standard antivirus software?

a. Trojan

b. Worm

c. Virus

d. Spyware

e. Adware

5. Which of the following is most likely to come with other malware?

a. Trojan

b. Worm

c. Virus

d. Spyware

e. Adware

6. Which of the following is bundled with the peer-to-peer file-sharing software, Kazaa?

a. Trojan

b. Worm

c. Virus

d. Spyware

e. Adware

7. Which of the following is most likely to install a "backdoor" internet connection?

a. Trojan

b. Worm

c. Virus

d. Spyware

e. Adware

8. Which of the following is most likely to be involved in a denial-of-service attack?

a. Trojan

b. Worm

c. Virus

d. Spyware

e. Adware

9. Which of the following is the only malware publicly documented as having been employed by the FBI to bring a suspect to trial?

a. Trojan

b. Worm

c. Virus

d. Spyware

e. Adware

10. Which of the following is most likely to steal your identity?

a. Trojan

b. Worm

c. Virus

d. Spyware

e. Adware

Answers:

1. c. virus. Trojans, worms, spyware, and adware all depend on your computer staying up and running. They use your computer's resources to accomplish whatever their designer intended, such as sending emails, displaying advertising, or stealing information from your computer. Viruses, however, are usually created by vandals who just want to damage as many computers as possible.

2. c. virus. Viruses are not stand-alone programs. Just as biological viruses must take over the cells of their host in order to function and reproduce; computer viruses must take over one or more files of the computer on which they are stored. Trojans, worms, spyware, and adware are all stand-alone programs that can run without the help of another application, though they often come bundled with other applications as a decoy, or with other malware.

3. b. worm. Worms are stand-alone programs that are often used to send spam emails, or emails containing viruses. Trojans often contain worms which are then installed for the purpose of sending spam emails, but the worms are what actually send the emails.

4. e. adware. In the strictest sense, adware is rarely patently illegal or destructive, and so antivirus software makers have traditionally avoided treating it as malware. Adware designers are usually large advertising companies with hundreds of millions of dollars, and they take care to insert end-user licensing agreements (EULA) that supposedly mean that the software is installed with permission. Also, adware will not usually do anything more destructive than show advertising. Nonetheless, adware can quickly multiply on a computer, hogging system resources and causing a computer to slow down or even malfunction. That's why most anti-spyware software makers target adware as well.

5. a. Trojan. By definition, Trojans bear other malware within them, just as the mythical wooden worse bore Greek warriors. The malware can be viruses, worms, spyware, or adware.

6. e. adware, though d. spyware, is also correct. Kazaa's developers, Sharman Networks, make most of their money from the advertising shown by the included adware. The adware typically runs even when the Kazaa software is not in use. Sharman Networks has adamantly denied that the adware that comes with Kazaa is spyware, since, like most adware, it comes with an end-user license agreement that says the user grants permission for the software to be installed. In reality, few Kazaa users, until recently, were aware of just how much adware was being installed on their machines (as much as a dozen or more). Plus, the adware does monitor your internet usage, and so is spyware in the strictest sense.

7. b. worm. Worms most commonly install a "backdoor" internet connection in order to send out data (for instance, spam emails or requests to remote servers) undetected.

8. b. worm. Worms, which most commonly install a "backdoor" internet connection on the host computer, are perfect for sending out the millions of server requests needed to achieve a denial-of-service attack. A denial-of-service attack is when a server is maliciously sent so many hits that it is overwhelmed and cannot continue to operate.

9. a. Trojan. The Trojan "Magic Lantern" was famously used to install monitoring software on the computer of a suspect who was later brought to trial partly on the strength of the evidence gathered.

10. e. Spyware. Spyware is malware that collects information from your computer and sends it to another remote machine, so by definition any software that steals your identity is spyware. However, spyware is often installed on your computer by a Trojan, or sent to you by another computer infected with a worm, so other kinds of malware pose an indirect threat of identity theft as well.