I have to confess that our various systems are a patchwork of different versions of Windows operated on the different work stations, even back to Windows XP Pro. I’m not certain what the servers are running.
Every year I buy the best preventive/detective solution from independent tests on this site:
http://www.av-comparatives.org/
It’s a problem... I didn’t realize that it was a multiple computer problem. All it takes is one weak link to gain trust thoughout the whole network you have if it isn’t adequately firewalled through a server.
In my old company, for a long time we had both a local peer to peer intranet in the company combined with independent, multiple access to the internet. It was an accident waiting to happen, although fortunately it didn’t, and the system was eventually modernized.