Hey, Charlie Miller! Let's Talk About Securing Autonomous Vehicles
Written by Niheer Patel
May 3, 2017
A recent Wired article on Charlie Miller (infamously known for remotely hacking and controlling a Jeep) claims that “open conversation and cooperation among companies” are necessary prerequisites to building secure autonomous vehicles. This seems rather far-fetched when so many companies are racing to dominate the future of the once-nearly-dead-but-newly-revived (remember the Big Three bailouts?) automotive industry. As naive as that part of the article sounds, what really blew my mind was the implication that the answer to re-designing security lies solely within the autonomous-vehicle industry.
The concept of security is not isolated to autonomous vehicles so there is no benefit in pretending that’s the case. Every IIoT industry is trying to solve similar problems and are surprisingly open to sharing their findings. I’m not saying that Miller needs to go on a journey of enlightenment through all other industries to create the ideal solution for security. I’m saying this has already been done for us, compliments of the Industrial Internet Consortium (IIC).
The IIC consists of 250+ companies across several industries – including automotive suppliers like Bosch, Denso, and TTTech – with the same fundamental problem of balancing security, safety, performance, and of course costs for their connected systems. If Wired and Miller are looking for an open conversation – it’s happening at the IIC. The IIC published the Industrial Internet Reference Architecture, which is available to everyone for free – as in “free beer,” especially if the car is doing the driving for you! The extensions to this document are the Industrial Internet Connectivity Framework (IICF) and Industrial Internet Security Framework (IISF). These documents provide guidance from a business perspective down to implementation, and the IISF is particularly applicable as it addresses Wired’s brief mentions to securing the connectivity endpoints and the data that passes between them.
Take a ride with me and see how we might modify the connected car’s architecture to protect against potential adversaries. Since we do not have any known malicious attacks on cars, we can start with Miller’s Jeep hack. Thanks to a backdoor “feature” in the Harmon Kardon head unit, Miller was able to execute unprotected remote commands quite easily. Through this initial exploit, he was able to reprogram a chip connected to the CAN Bus. From there, he had nearly full control of the car. You’re thinking, “just remove that unprotected interface,” right?
Miller would not have stopped there, so neither shall we. Assuming we could still find an exploit that granted us access to reprogram the ARM chip, then Wired’s article rightly suggests establishing an authenticated application – perhaps starting with secure boot for the underlying kernel, leverage ARM Trust Zone for the next stage of critical-only software, and implement some sort of authentication for higher level OS and application processes. Your device endpoint might start to look like a trusted application stack (Figure 1 below). I can only guess how much this head unit costs now, but to be fair, these are valid considerations to run a trusted application. The problem now is that we haven’t actually connected to anything, let alone securely. Don’t worry, I won’t leave you by the roadside.
Many of these trusted applications connect up directly to the CAN Bus, which arguably expands the attack surface to the vehicle control. The data passed between these applications are not protected from unauthorized data writers and readers. In the case of autonomous taxis, as Wired points out, potential hackers now have physical access to their target, increasing their chance of taking over an application or introducing an imposter. Now the question becomes: can applications trust each other and the data on the CAN bus? How does the instrument cluster trust the external temperature data? Does it really need to? Maybe not and that’s ok. However, I am pretty sure that the vehicle control needs to trust LIDAR, Radar, cameras, and so on. The last thing anyone wants to worry about is a hacker remotely taking the car for a joyride.
We are really talking about data authenticity and access control: two provisions that would have further mitigated risk against Miller’s hack. Securing the legacy applications is a good step, but let’s consider the scenario where an unauthorized producer of data is introduced to the system. This trespasser can inject commands on the CAN Bus – messages that control steering and braking. The CAN Bus does not prevent unauthorized publishers of data nor does it ensure that the data comes from the authenticated producer. I’m not suggesting that replacing the CAN Bus is the way forward – although I’m not opposed to the idea of replacing it with a more data-centric solution. Realistically, with a framework like Data Distribution Services (DDS), we can create a layered architecture as guided by the IISF (Figure 2 below). The CAN Bus and critical drive components are effectively legacy systems for which security risk can be mitigated by creating a DDS databus barrier. New components can then be securely integrated using DDS without further compromising your vehicle control. So what is DDS? And how does it help secure my vehicle? Glad you asked.
Imagine a network of automotive sensors, controllers, and other “participants” that communicate peer-to-peer. Every participant receives only the data it needs from another participant and vice versa. With peer-to-peer, participants in that network can mutually authenticate and if our trusted applications hold up, so does our trusted connectivity. How do we secure those peer-to-peer connections? TLS, right? Possibly, but with the complexity of securing our vehicle we want the flexibility to trade off between performance and security and apply access control mechanisms.
Let’s back up a little and re-visit our conversation about the IICF, which provides guidance on connectivity for industrial control systems. The IICF identifies existing open standards and succinctly attributes them to precise functions of an Industrial IoT system. At its core, an autonomous vehicle, as cool as it sounds, is just an Industrial IoT system in a sleek aerodynamic body with optional leather seats. So what does the IICF suggest for integrating software for an Industrial IoT system, or more specifically, autonomous systems? You guessed it! DDS: an open set of standards designed and documented through open conversations by the Object Management Group (OMG). An ideal automotive solution leveraging DDS allows system applications to publish and subscribe to only messages that they need (see Figure 3 below for our view of an autonomous architecture). With this data-centric approach, we can architecturally break down messages based on criticality for safety or need for data integrity.
And now that we’ve established a connectivity solution for our autonomous vehicle, we can get back to talking about security and our TLS-alternative: a data-centric security solution for a data-centric messaging framework. With DDS Security, Industrial IoT system architects can use security plugins to fine-tune security and performance trade-offs, a necessary capability not offered by TLS (Figure 4 below). Authenticate only select data topics but no more? Check. Encrypt only sensitive information but no more? Check. Actually, there is more. Casting aside centralized brokers, DDS Security offers distributed access control mechanisms dictating what participants can publish or subscribe to certain topics without single points of vulnerability. This means that Miller’s unauthorized application would be denied permission to publish commands to control braking or steering. Or if Miller compromised the data in motion, the data subscriber could cryptographically authenticate the message and discard anything that doesn’t match established policies. Can we say our autonomous vehicle is now completely secure? No, because as Miller made it perfectly clear, we still need more conversations. However, we can certainly say that DDS and DDS Security provide the forward-looking flexibility needed to help connect and secure autonomous systems.
So, to Mr. Charlie Miller (and of course Mr. Chris Valasek), your work is amazing and vision inspiring, but I think you need to look across industries if you want to talk openly about redesigning automotive architecture. When you and all the other Charlie Millers in the world want to have that open conversation, come knock on our door. At RTI, we are ready to talk to you about autonomy, Industrial IoT, safety and security, and everything you else you believe should define cars of tomorrow.