Virus using a macro language, e.g. in Office documents
'Macro virus' refers to any virus that uses macro languages, but most commonly to the large number of viruses that targeted Microsoft's Office software in the 1990s.
Macro languages are intended to allow the automation of tasks within a program. However, in some systems these languages can be exploited to carry out more malicious tasks, including infecting other files and changing data in them. In Office programs affected by macros, the template file is infected when a malicious file is loaded, and thus each further file loaded is infected in turn. The majority of macro viruses target Word documents (.doc) and Excel spreadsheets (.xls), but macro viruses for PowerPoint and other Office products also exist.
Many of the security holes in the macro languages were closed with the release of Office 2000, and since then macro viruses have become considerably less prevalent.
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