While not damaging, it spreads easily. WM.Wazzu - The Wazzu macro virus currently has at least 100 variants and has spread throughout the world. The original Wazzu virus consists of a single page of relatively simple code and was not encrypted. Because of this, everyone who caught the virus had a working copy of the virus source code to play with which accounts for the large number of variants of this virus. WM.NPAD - The NPAD macro virus also spreads rapidly.
Most variants display text on the screen after some number of infections.
They do no damage other than spread. Macro viruses use the built-in Word. Basic macro language available in Microsoft Word 6.0 and later. A variant of this language existed in Word 2.0 for Windows, but these macro viruses only run on the version of Word. Basic in Word 6.0 and later.