Microsoft released a security advisory today for all modern versions of Microsoft Word and Microsoft Works. According to the document, a vulnerability in the popular word processing software programs is being actively exploited, and can be triggered simply by opening a carefully modified Word document.
Microsoft suggests that users "not open or save Word files," even from trusted sources. "As a best practice, users should always exercise extreme caution when opening unsolicited attachments from both known and unknown sources," the company said.
Do not open or save Word files that you receive from un-trusted sources or that you receive unexpectedly from trusted sources. This vulnerability could be exploited when a user opens a specially crafted Word file. [emphasis mine]