Nice sub section on the website gnu.org about how proprietary software is often automatically also malware. Normally I do not link to sub sections, but this was kind of important to me, because it should be basic knowledge to people.
There is so much talk about computer security issues, but most do not understand what the root of the problem is, which is proprietary software, that opens up all the possibilities of abuse.
So rather than checking each invidiaul program or service if it is malware or not, one should understand the basics, then he will be able to tell himself what is malware and what not. Well it is not even that hard, the title "Proprietary Software Is Often Malware" already gives it away.
This websites has some of the best information on that topic, you do not need to read it all, but some of it, to get an idea what the issue is about.