Types of Viruses

Computer viruses come in a variety of types. Breaking them into categories is not easy as many viruses have multiple characteristics and so would fall into multiple categories. We're going to describe two different types of category systems: what they infect and how they infect. Because they are so common, we're also going to include a category specific to worms.

What They Infect

Viruses can infect a number of different portions of the computer's operating and file system. These include:

• System Sectors
• Files
• Macros
• Companion Files
• Disk Clusters
• Batch Files
• Source Code
• Worms using Visual Basic

How They Infect

Viruses are sometimes also categorized by how they infect. These categorizations often overlap the categories above and may even be included in the description (e.g., polymorphic file virus). These categories include:

• Polymorphic Viruses
• Stealth Viruses
• Fast and Slow Infectors
• Sparse Infectors
• Armored Viruses
• Multipartite Viruses
• Cavity (Spacefiller) Viruses
• Tunneling Viruses
• Camouflage Viruses
• NTFS ADS Viruses

Now either click on the virus topic you are interested in or read about each in sequence...