How do antivirus companies find new viruses?

Firstly, this depends on the antivirus company. There are multiple strategies used. 1. "Honeypots" - PCs that imitate common user behavior or that are exposed to the network. 2. read more

This helps the antivirus software to detect new or a variant or an altered version of malware, even in the absence of the latest virus definitions. Antivirus programs use heuristics, by running susceptible programs or applications with suspicious code on it, within a runtime virtual environment. read more

The anti-virus companies don't have to introduce viruses into the internet because there are enough nuts around to do it for them. Antivirus programs exist BECAUSE of the screwballs who create malicious code on their own. read more