This older article from 2012 is still relevant 5 years later.  Scammers use fear to convince users to share sensitive information or charge to fix your PC. And malware can be planted on the PC, when users may not be aware of these tactics.  

https://securelist.com/trying-to-unmask-the-fake-microsoft-support-scammers-17/33734/

I’m pretty sure that most of you guys know about the recent phone scam which is circulating right now. The scam is pretty simple; they pretend to be from a department within Microsoft which has received indications that your computer is infected with some malware.

They will then offer (for free) to verify if this is the case. If the victim agrees on this, they will ask the victim to perform certain actions, and also type certain commands, which will trick a non-experienced user that the output is actually showing that the computer is infected.

I just want to mention that there is no such department at Microsoft, and they would never call up customers offering this. So if you ever get a call from Microsoft stating that there are some indications that your computer is broken or infected – please hang up!

Well, they have called me several times, and finally Ii got fed up with this and started to play along. At the same time I had my virtual machines running and was recording everything that they were doing. The goal was to find out who they were and exactly what the scam was. Luckily I was able to get hold of information such as their internal IP addresses, the PayPal accounts used to wire money and the numbers they are calling from.

After collecting all the information, i have now contacted all the appropriate people such as the security team at PayPal, various law enforcement agencies with the hope that we can stop these people. They are stealing alot of money from innocent people. I know that people have been warned about these scams, but my conclusion is that they are still calling people because they are still making money out of these scams.

The software that they were using was not malicious in any way, which means that no security software can detect these types of scams. This is one of the main reasons for this article and others like it – we need to keep informing people about it until the cybercriminals are forced to stop.