Macro viruses were at one time the most prevalent virus type. Although worms and mixed threat attacks are now most common, macro viruses continue to be among the most common types of file infectors, especially in Microsoft™ Office documents and compressed files.
Macro viruses are not confined to one operating system; they are application specific, so they can be spread between DOS, Windows, Macintosh, and OS/2 systems. With the ability to travel by email, and the increasing power of macro code, macro viruses remain a true threat.
To combat macro viruses, Trend Micro has developed MacroTrap, a heuristic
scanning method that performs a rules-based examination of macro code
within a document. Macro virus code is typically a part of the invisible
code (.dot, for example, in Microsoft Word) that travels with the document.
MacroTrap checks the code for signs of unknown macro viruses by seeking
out the instructions that perform virus-like activity