What is a Macro Virus?

With the popularity and everyday use of the Internet increasing, and the threat of viruses growing everyday, many Internet users have implemented Anti-Virus applications to help them remain safe from virus attacks while they are on the Internet.

Macro viruses require user action to execute once they have been downloaded or make their way onto a computer system. The viruses are typically written in a scripting language that is commonly used to create macros for use within applications. Some of these macro viruses are more an annoyance than a threat to the security of a computer system. An example would be a macro virus that produces undesired text within Microsoft Word® when a certain combination of keys are pressed.

Many applications, including Microsoft Word® and Excel®, disable the execution of macros by default. This helps protect the unsuspecting user from accidentally executing a macro virus. These applications remain macro aware and with a few changes to the security settings, trusted macros or all macros can be enabled.

Trusted macros are the safest macros and are least likely to contain a macro virus. These files are typically created by the user who is going to use the macro or by a corporate IT department for use only within their organization.

A macro virus can be placed on a computer in the same way as a self-executing virus, using email, or file downloads from the Internet. As with other types of viruses, other users can also pass macro viruses along to co-workers or others using floppy disks or flash memory drives which they may not realize they have been infected with.

As a general rule, it is often best not to accept files with macros embedded in them or to use macros created by other people. Doing a bit of research on the Internet about the use of macros can help a user create macro files for their own use and lessen the likelihood of a macro virus infection. If a user must download a macro template or file containing macros, the source of the download should be trusted and verified to be virus free.

The disabling of macros by default has been a giant step forward in reducing the spread of macro virus infections but it continues to be the responsibility of the user to be mindful of the files received or downloaded from the Internet — both executable and macro — to reduce the likelihood of a virus or macro virus from infecting their computer.