Another computer has access to your computer. How do I identify the source?

Comodo has once again protected my PC—and me. It blocked “CSS” until the threat was neutralized.
My question:
After neutralizing the threat, CIS advises me to terminate the remote connection to avoid any further risk. However, I don’t know who accessed my PC; this time, it wasn’t Adobe. I received this warning when I opened Photoshop Elements. I’m not sure if Adobe was the cause or if it was some sort of “add-on” or “piggybacking” process—though I suspect it wasn’t Adobe.
In any case, the warning from Comodo CIS states: “Another computer is accessing your computer. Someone else could potentially monitor my activity and connections, or even steal passwords and other sensitive information.” It mentions that the connection is being blocked until the threat is resolved, and instructs me to wait until “CSS” is released. I am told to wait while a timer counts down (approximately 3 minutes).

How can I find out, after the fact, who attempted to access my PC? I couldn’t find any information, for instance, in the Task Manager.

ThX for help!