MacroTrap

Trend Micro's MacroTrap performs a rules-based, line-by-line examination of all macro code that is saved in association with a document. This code analysis is called a "heuristic," or "intelligent" search because it allows the virus engine to detect new viruses that have not been included in the virus pattern file.

Macro virus code is typically contained as a part of the invisible template (.dot, for example, in Microsoft Word) that travels with many documents. MacroTrap checks the template for signs of a Macro virus by seeking out key instructions that perform virus-like activities--instructions to copy parts of the template to other templates (replication) or to execute potentially harmful commands (destruction).

Macro viruses are the most common type of viruses, responsible for the greatest number of infections. This is because macro viruses are relatively easy to produce, spread easily (for example via email attachments), and are platform independent. Any computer running Word, for example, can become infected with the Concept virus -- regardless of whether the Word document is opened on a PC, an iMac, or on another platform.