While it's true that all recent versions of MS Office supposedly require the user's permission to run a macro, a wee little oversight at Redmond Security Central makes it possible for an RTF (Rich Text Format) document opened by Word to execute a macro automatically if it's embedded in a template.
"When Word is used to open a document that’s based on a template, both the document and the template should be checked for macros. This vulnerability involves a case in which this isn’t done correctly," an MS security bulletin explains, doing its damnedest not to say 'we goofed'.
Macros run on a machine or network at the user's level of permission, so of course a malicious one can perform quite a lot of mischief.
In this case, developing an exploit would be child's play. The required template could be fetched from a remote location, such as a Web site to which the feature-rich Word can connect automatically. This would be the preferred MO for someone trying to propagate via e-mail a macro virus exploiting the RTF vulnerability.
RTF is something of the lingua franca of word processing, readable by just about every application ever designed, so it's still in common use wherever people have to collaborate whilst using different software.
Affected programs include Word 97; Word 98 (J); Word 2000; Word 98 (Mac); and Word 2001 (Mac), but not Word 2002.
"Previous versions [of Word] are no longer supported and may or may not be affected by this vulnerability," MS says. It's reasonable to assume that they are affected, so there we have one more little motive to upgrade. ®