WM/Sad is a simple Word macro virus that does not do anything but replicate.
It infects the global template when an infected document is opened. After that every closed document will be infected.
Based on the settings of your F-Secure security product, it will either automatically delete, quarantine or rename the detected program or file, or ask you for a desired action.
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See the manual for your F-Secure product on the Help Center.
Submit a file or URL for further analysis.
It contains the following macro description:
Installed to your NORMAL template as AutoClose to clean the prank macros from any documents that you open then close.
This description is on "AutoClose" macro in the global template, and on "Sad" macro on infected documents. It is viewable from "Tools/Macro" dialog.