Microsoft has issued a security bulletin with the steps needed to disable automatic background document updating via DDE. Apparently, bad guys have figured out a way to exploit local machines by sending "specially-crafted" Office doc attachments. MS is pretty vague about the details, and whether existing security features can block it. It looks like there might be some scenarios where ODBC sources are updating Office docs via DDE, so might affect your apps.

Details:

https://technet.microsoft.com/library/security/4053440.aspx