I listened to a news story on NPR’s On The Media recently about “Cyber Warfare” and assessing it’s true threat. On the one hand, it seemed like another misguided report from a clueless news media. On the other hand, though, it did make me think a bit.
Much of the talk about Cyber Warfare revolves around attacking the various SCADA systems used to control the nation’s physical infrastructure. By today’s standards, many of these systems are quite primitive. Many of these systems are designed for a very specific purpose, rarely upgraded to run on modern operating systems, and very rarely, if ever, designed to be secure. The state of the art in security for many of these systems is to not allow outside access to the system.
Unfortunately, if numerous reports are to be believed, a good portion of the world’s infrastructure is connected to the Internet in one manner or another. The number of institutions that truly air gap their critical networks is alarmingly low. A researcher from IO Active, who provided some of the information for the aforementioned NPR article, used SHODAN to scour the Internet for SCADA systems. Why use SHODAN? Turns out, the simple act of scanning the Internet for these systems often resulted in the target systems crashing and going offline. If a simple network scan can kill one of these systems, then what hope do we have?
But, air gapping is by no means a guarantee against attacks since users of these systems may regularly switch between connected and non-connected systems and use some form of media to transfer files back and forth. There is precedence for this with the Stuxnet virus. According to reports, the Iranian nuclear facility was, in fact, air gapped. However, Stuxnet was designed to replicate onto USB drives and other media. Plug an infected USB drive into a targeted SCADA system and poof, instant infection across an air gapped system.
So what can be done here? How do we keep our infrastructure safe from attackers? Yes, even aging attackers…
Personally, I believe this comes down, again, to Defense in Depth. With the exception of not building it in the first place, I don’t believe that there is a way to prevent attacks. And any determined attacker will eventually get in, given time. So the only way to defend against this is to build a layered defense grid with a full monitoring back end. Expect that attackers will make it through one or two layers before being detected. Determined attackers may make it even further. But if you build you defenses with this in mind, you will stand a better chance at detecting and repelling these attacks.
I don’t believe that air gapping systems is a viable security strategy. If anything, it can result in a false sense of security for users and administrators. After all, if the system isn’t connected, how can it possibly be infected? Instead, start building in security from the start and deploy your defense in monitored layers. It works.