My dad was pretty shocked how easily some malware managed to get onto his work system a couple of months ago from an ad on an otherwise legitimate site, despite

My dad was pretty shocked how easily some malware managed to get onto his work system a couple of months ago from an ad on an otherwise legitimate site, despite fully patched IE and up-to-date anti-virus software. The anti-virus software did catch it, but only after it had made it onto the system. He got a mac and uses Safari at home now.