Internet Safety: Viruses

Table of Contents

1. Introduction
2. Viruses, Trojans and Worms
   1. Types of Virus
   2. Trojans
   3. Virus Quiz 1
   4. Worms
   5. Logic Bombs and Time Bombs
   6. Virus Quiz 2
   7. Screen Savers
   8. Image Viruses
   9. Virus Quiz 3
   10. Macro Virus
   11. Resident Virus
   12. Virus Quiz 4
   13. Script Viruses
   14. Stealth Viruses
   15. Virus Quiz 5
   16. Mail Bombs
   17. Backdoors and Rootkits
   18. Virus Quiz 6
3. Example Viruses
4. Anti-Virus Software

Macro Virus

We've already mentioned that some applications, like word processors and spreadsheets, can be programmed to change the way they work. To do this they store programs called Macros. Unfortunately these macros, as well as doing useful things like automatically formatting a document, can be used to attack your computer.

A macro virusinfects an application like Microsoft Word and causes a sequence of actions to happen when the application is opened. One common effect is the insertion of comic text into a document. Macro viruses are often spread via e-mail. One well-known example is the Melissa virus. Another example is the Nimba worm which attacked systems in many different ways including via e-mail and back doors.

Because macros are stored in documents they sometimes seen as less of a threat than other programs, but this is not really the case as they can do serious damage. You should never open documents if you are unsure of where they come from. Opening a document allows any macro viruses it contains to run and your computer can become infected.

Next: Resident Virus