Re: Another fear mongering advert
Actually, when I was a newbie at work, I spotted we had a virus infection using exactly that. Being a technician, I often needed drivers or utilities to be accessible. Because large USB sticks were expensive, and external hard drives weren't really a thing yet, I had several gigs of them in a shared folder. Read access only. One day, I noticed the machine was struggling a little bit. Seeing nothing out of the ordinary running, I unplugged the machine from the network so I could take it over to a little workbench area I had and look at it. The machine become responsive immediately, so I plugged it back in and started logging connected IPs. Sure enough, two IPs had thousands of failed connections between them. I reported those IPs to the technicians supporting the machines. Sure enough, both were infected with a virus. So, I detected there was a virus on two machines I had no access to based on how they were behaving toward my machine. That was 20 years ago. Technology has improved since then.