For example, consider a software that wants to package all txt files in the /user/Desktop directory and upload them to its own server. I am not a programmer, but I know it can be done very easily with code. Maybe this can be done with a single line of code. Even a lot of well-known software can do this. Pdf viewer, media player etc.
It wouldn't crash or slow down the PC, only scan txt files on Desktop and upload to its own servers. For example I have seen a lot of program that request outbound internet connection on my Firewall Software, and these programs are well-known programs used by millions of people.
I'm guessing antivirus solutions don't block these processes. Is this a valid concern for ordinary PC users? Many users don't know or understand firewalls.
Is there something I missed? Maybe I'm wrong and Antivirus or Windows OS can detect and block this easily.
Note: I don't want suggestions such as use Linux or Open Source programs. I am not researching how to avoid this.
I just wonder if this process could be that easy?