Understanding the Component Object Model (COM) and COM hijacking

COM is a binary standard for software componentry introduced by Microsoft in 1993, which defines a set of rules for how software components interact with each other and allows inter-process communication. It was developed by Microsoft to address the need for interoperability between applications.

COM is the basis of many other technologies, such as OLE, COM+, DCOM, ActiveX, Windows User Interface, Windows Runtime, and many others. Basically, COM is just middleware that sits between two components and allows them to communicate with each other.

One example of how COM is used can be demonstrated with how Object Linking and Embedding (OLE) works: if you want to include, for example, an Excel table in your PowerPoint presentation. Usually, to allow this, without COM, PowerPoint would need to have the actual code implemented that makes Excel work how it works. But since this would be a waste of resources and redundant...