This attack could pose a serious security threat. You should take immediate action to stop any damage or prevent further damage from happening.
This signature detects attempt to exploit a buffer overflow in Microsoft Word by sending a specially crafted file.
Microsoft Word is a word processor available for multiple platforms.
Word is prone to a buffer-overflow vulnerability that occurs when the application processes a Word file with a malformed record value.
An attacker can exploit this issue to execute arbitrary code in the context of the currently logged-in user. Failed exploit attempts will likely result in denial-of-service conditions.
The vendor has released an advisory and updates. Please see the referenced advisory for details.