This excellent session by Alexander Bolshev (@dark_k3y) was a very pleasant surprise, and it's a bit frustrating that it is one of the three lost S4x14 videos.
We were concerned that it would be a bit S4x13 / insecure by design / low hanging fruit, but HART has received so little attention that we thought it was worth including in S4x14. HART is widely used in DCS to connect controllers and instruments. The HART Foundation says over 30 million HART devices are deployed.
Alexander covers the protocol in the early slides, but make sure you look at slides 16-21 where he shows how he can change the RTU's Polling Unit ID (who the RTU expects to poll it) to create a man-in-the-middle attack.
There are a number of other HART protocol attacks described, but I was most interested in his HRT Shield board - a high-power low-noise HART modem Arduino shield for sniffing, injecHng, and jamming current loop. He brought over some boards that we are building up to have in our Rack when we go out on an assessment.
I should note, mainly to avoid an email from Jeff, that WirelessHART has integrated security such as source/data authentication and encryption. As we walk through plants and factories we are seeing a number of these WirelessHART devices. They are easy to spot because they can be deployed in the most physically convenient place without worrying about wiring.