This indicates an attack attempt against an Information Disclosure vulnerability in Microsoft Office.
The vulnerability is due to an error in the application when handling a crafted Office Open XML file with ActiveX. A remote attacker can exploit this to gain unauthorized access to sensitive information, via a crafted Open XML file.
Microsoft Office 365 ProPlus
Microsoft Office 2019
Microsoft Office 2016
Microsoft Office 2013 RT Service Pack 1
Microsoft Office 2013 Service Pack 1
Microsoft Office 2010 Service Pack 2
Information Disclosure: Remote attackers can gain sensitive information from vulnerable systems.
Apply the most recent upgrade or patch from the vendor: