So far and discounting the bad old days say up to a decade ago and even now the security problems have been user induced.
1. Installing trojans, malware, ransomware. There is NO single solution to this one as all it takes is for the antivirus suite to not know about the new thing.
2. All the items that I've seen to date were caused by the PC owner. The owner went out of their way to find a CRACKED APP or a PLUGIN REQUIRED TO WATCH PRON and BLAMMO, the PC is infected.
As such my view is to upgrade the security we upgrade the users.
I am still using windows 7 operating system and using Microsoft security essentials to secure my computer. How I can upgrade my security system?