The term 'Malware' means any software that performs a malicious action, and by far the most prolific and insidious form of malware is macro-based.
Macro code can bypass almost every security measure on the market.
Macro-viruses are just the tip of the iceberg of Macro Malware. A macro is no longer simply a program consisting of commands equivalent to a sequence of keystrokes and mouse-clicks. Macros are full-blown programs, written in very powerful programming languages. Documents are best thought of as 'containers' capable of holding not only the text seen on screen, but many kinds of unseen elements, including macro programs. When you open a document containing macros, numerous ways exist for the macro programs to trigger, without your knowledge or consent.