A Macro is a short passage of code attached to Microsoft Office Word Processing documents. They are written in the programming language Visual Basic, and are set to trigger on launch on Microsoft Office files or upon pressing a certain button or key. They can also be exploited to execute malicious code on an unsuspecting victim, such viruses can be saw in . These are not bots but Macros are scripted hacks. These can be turned into viruses easily.
These scripts can't do that much except turn into viruses. When they turn into viruses they can easily turn a bit of script , into a dangerous virus that may easily spread. It spreads easily by repeating the script many times in a fast pace. Whenever they turn into viruses the scripts may become more long and harmful like not being able to see the damage of the files. Stormworm is a good example of being an invisible virus / trojan. Many viruses are made out of Macros.
Never underestimate a Macro.