I see a bunch of folks talking about whether PCs are connected to the Internet and &quot;why was it running antivirus in the first place?&quot; It&#x27;s called Defense in Depth.<p>It Does Not Matter if the device is connected to&#x2F;able to reach the Internet.<p>First, it probably can reach the Internet in some way simply by being networked. I don&#x27;t think I&#x27;ve ever seen a medical office (can&#x27;t speak about hospitals) where medical diagnostic equipment was on a fully-separate network able only to talk to other network equipment and specified data destinations (PACS servers).<p>Second, I&#x27;m not concerned about unpatched, unprotected machines being infected from the Internet. Odds are they&#x27;re running a restricted version of Windows, with a custom shell and a lot of stuff stripped out. I&#x27;m concerned that they&#x27;re going to be infected by another machine on the network that&#x27;s gotten infected. With all the past SQL Server security issues a decade or more ago, how many people think those SQL Server boxes could be directly reached from outside the local network?<p>The conjunction of those two is that even if you firewall all that stuff off, the PACS servers are still on both networks, and are probably running much more interesting and vulnerable stuff than the device controllers.<p>Sure you can fully wall everything off - it&#x27;s really easy, just do your X-rays onto film, burn your MRIs and ultrasounds onto CDs, and print your EKGs for later scanning. Oh, and listen to people complain about how out-of-date your systems and procedures are.<p>There are other factors that come in as well - sure, every device manufacturer could provide fully bespoke diagnostic displays developed from the ground up in artisanal software shops providing full employment for assembly programmers working on embedded systems, along with cohorts of graphic designers creating glorious steampunk-styled interfaces. That&#x27;s a beautiful dream, keep having it.<p>For the rest of the world, creating a UI on that custom embedded system running on something from RIM&#x2F;Blackberry (yeah, they own QNX) is just going to get them crap from people because of A) how clunky it probably looks and B) How could they even consider allowing direct user interaction with the RTOS that was chosen to ensure that the dangerous bits in contact with patients&#x2F;radiation&#x2F;irradiated patients were safe?<p>There&#x27;s a beautiful world out there somewhere where everything is safe and secure and seamless and updated. The rest of us live in worlds where Joe in Marketing&#x27;s PC gets infected with something that allows an attacker to start scanning the network for unpatched vulnerabilities on any system, which leads to an out-of-date install of IIS on a legacy server that hasn&#x27;t been updated because there&#x27;s no longer a contract with the vendor (or no vendor) but it&#x27;s around because there&#x27;s a statutory requirement to keep the data on that system for 7-10 years.<p>There&#x27;s a lot of ugliness out there. Antivirus is a way to try to ensure that when (not if) some of it hits you the repercussions are minimized.