A team of researchers from the University of Michigan, University of Pennsylvania and NASA have identified a potentially serious vulnerability in networking technology used in spacecraft, aircraft, and industrial control systems.
The flaw affects Time-Triggered Ethernet (TTE), a networking technology specifically designed for real-time applications and cyber-physical systems with high safety and availability requirements.
TTE is often used to reduce costs and improve efficiency as it allows mission-critical components to exist on the same network hardware as less important systems.
For instance, life support systems can share the network with onboard experiments in the case of spacecraft, robot control systems can share a network with data collection systems in manufacturing facilities, or passenger Wi-Fi could be on the same network as flight control systems in the case of airplanes — this is not the case in current commercial airplanes.
In a research paper detailing their findings, the researchers explained that they looked at the isolation of time-triggered (TT) traffic from non-critical best-effort (BE) traffic, with the second supposedly not being able to interfere with the operation of TTE devices.
The attack has been dubbed PCspooF because it involves TTE synchronization messages called protocol control frames (PCFs).
“PCspooF is based on two key observations,” the researchers said. “First, it is possible for a BE device to infer private information about the TT part of the network that can be used to craft malicious synchronization messages. Second, by injecting electrical noise into a TTE switch over an Ethernet cable, a BE device can trick the switch into sending these malicious synchronization messages to other TTE devices.
“Our evaluation shows that successful attacks are possible in seconds, and that each successful attack can cause TTE devices to lose synchronization for up to a second and drop tens of TT messages — both of which can result in the failure of critical systems like aircraft or automobiles.”
In order to demonstrate their findings and the potential impact of an attack in a real-world scenario, the researchers simulated a scenario involving a space mission with a crewed spacecraft attempting to dock with a robotic spacecraft. Using real NASA hardware and software, they showed how a small malicious device on board the capsule could stealthily send disruptive messages that would cause it to veer off course and miss its target.
The findings have been reported to device manufacturers and organizations that use TTE, and the researchers said some of them are working on implementing mitigations.
“We hope the description of our attack, as well as the mitigations we identified, will influence the deployment of current TTE systems, as well as the designs of future mixed-criticality network technologies,” the researchers said.
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