Is there a possibility that malware on a computer could be providing remote access to an external party without the computer user being aware? I.e., some kind of hidden active remote access tool?
I.e., the computer I am using now, is there some chance an external user is viewing my active desktop without me being aware of it?
Yes it's possible.
An obvious example would be a Remote Access Trojan (RAT). Once your computer is infected they can do essentially whatever they're set up to do. This includes monitoring your screen, logging keystrokes, and accessing webcams.
My personal experience with this was being infected with the Blackshades RAT a few years ago. I was monitored for about two days and on the final day the kid on the other end clearly got impatient with me and demanded to know multiple credentials via a chatbox he put in the middle of my screen.
My solution at the time was to remove my usb wireless card to prevent him from sending any further commands, format the computer, and reinstall from scratch.
Yes this is very possible. Remote Administration Tools (RATS) such a DarkComet or Blackshades are commonly used for this.
