Computer Virus Types

Macro virus

• A type of computer virus that is encoded as a macro embedded in a document.
• According to some estimates, 75% of all viruses today are macro viruses.
• Once a macro virus gets onto your machine, it can hide itself in all future documents you create
• Antivirus programs can protect your system against most macro viruses.

Trojan horse

• A destructive program that masquerades as a small application.
• Unlike viruses, Trojan horses do not replicate themselves but they can be just as destructive.
• The term comes from a story in Homer's Iliad, in which the Greeks give a giant wooden horse to their foes, the Trojans, ostensibly as a peace offering. But after the Trojans drag the horse inside their city walls, Greek soldiers sneak out of the horse's hollow belly and open the city gates, allowing their compatriots to pour in and capture Troy.

Worm

• A small program that copies itself over a computer network and usually performs malicious actions, such as using up the computer's resources and possibly shutting the system down.