Many of the programs available to today's computer user are very popular and universally accepted software applications. Therefore, the chances of a number of people using similar software is high, and this allows a great deal of sharing of information between users.
In the past, it was typically necessary for a virus to be included in an executable file (like an application file) and antivirus software was designed to search for this specifically. Now, we have a new set of viruses that use macros to infect data files. Macros are customizable features in WORD, EXCEL and other software applications. With macros, users can program certain keystrokes to execute certain commands, or to specify certain processes to run when documents are opened or closed. These new viruses range in their severity from "Colors" which changes a user's screen color to "FormatC" and "Hot" which may delete files on a user's hard drive. Winword Concept was the first virus ever to infect documents rather than executable code. It is also the first ever multi-platform virus, capable of infecting Windows 95, Windows NT, and the Macintosh OS as well as Windows 3.X computers running Microsoft Word 6.
Microsoft is not the only popular word processor targeted by these new age viruses. The "Green Stripe" is a virus that is capable of infecting Lotus and Ami Pro Word documents. Though it seems harmless, this virus is known to do a search and replace function of 'Its' with 'It's.' Even the new operating system from Microsoft, Windows 95, is a target for a new virus called 'Boza.'
Word 6 Macro Virus
The CASG-IFEC page has great information on macro viruses in word
processors.
http://www-tec.open.ac.uk/virusnews/virus_news.html
Microsoft has a short explanation and a faq, but their page directs
you to good sources.
http://www.microsoft.com/msword/freestuff/mvtool/mvtool2.htm
The first virus for Windows 95: The Boza Virus
Microsoft has a brief explanation of the BOZA virus.
http://www.microsoft.com/windows/pr/boza.htm
Symantec has great information about and fixes for the BOZA virus.
http://www.symantec.com/avcenter/boza.html