There has been a dramatic shift in the platforms targeted by attackers over the past few years. Up until 2016, browsers tended to be the most common attack vector to exploit and infect machines but now Microsoft Office applications are preferred, according to a report published here during March 2019. Increasing use of Microsoft Office as a popular exploitation target poses an interesting security challenge. Apparently, weaponized documents in email attachments are a top infection vector.
Object Linking and Embedding (OLE), a technology based on Component Object Model (COM), is one of the features in Microsoft Office documents which allows the objects created in other Windows applications to be linked or embedded into documents, thereby creating a compound document structure and providing a richer user experience. OLE has been massively abused by attackers over the past few years in a variety of ways.