Designers are increasingly using mixed-criticality networks in embedded systems to reduce size, weight, power, and cost. Perhaps the most successful of these technologies is Time-Triggered Ethernet (TTE), which lets critical time-triggered (TT) traffic and non-critical best-effort (BE) traffic share the same switches and cabling. A key aspect of TTE is that the TT part of the system is isolated from the BE part, and thus BE devices have no way to disrupt the operation of the TTE devices. This isolation allows designers to: (1) use untrusted, but low cost, BE hardware, (2) lower BE security requirements, and (3) ignore BE devices during safety reviews and certification procedures.We present PCSPOOF, the first attack to break TTE’s isolation guarantees. PCSPOOF is based on two key observations. 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. We also show that, in a simulated spaceflight mission, PCSPOOF causes uncontrolled maneuvers that threaten safety and mission success. We disclosed PCSPOOF to aerospace companies using TTE, and several are implementing mitigations from this paper.
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A test bed study of network determinism for heterogeneous traffic using time-triggered ethernet
Future tactical communications involves high data rate best effort traffic working alongside real-time traffic for time-critical applications with hard deadlines. Unavailable bandwidth and/or untimely responses may lead to undesired or even catastrophic outcomes. Ethernet-based communication systems are one of the major tactical network standards due to the higher bandwidth, better utilization, and ability to handle heterogeneous traffic. However, Ethernet suffers from inconsistent performance for jitter, latency and bandwidth under heavy loads. The emerging Time-Triggered Ethernet (TTE) solutions promise deterministic Ethernet performance, fault-tolerant topologies and real-time guarantees for critical traffic. In this paper we study the TTE protocol and build a TTTech TTE test bed to evaluate its performance. Through experimental study, the TTE protocol was observed to provide consistent high data rates for best effort messages, determinism with very low jitter for time-triggered messages, and fault-tolerance for minimal packet loss using redundant networking topologies. In addition, challenges were observed that presented a trade-off between the integration cycle and the synchronization overhead. It is concluded that TTE is a capable solution to support heterogeneous traffic in time-critical applications, such as aerospace systems (eg. airplanes, spacecraft, etc.), ground-based vehicles (eg. trains, buses, cars, etc), and cyber-physical systems (eg. smart-grids, IoT, etc.).
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- Award ID(s):
- 1738420
- NSF-PAR ID:
- 10073109
- Date Published:
- Journal Name:
- 2017 IEEE Military Communications Conference, MILCOM 2017
- Page Range / eLocation ID:
- 611 to 616
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/MILCOM.2017.8170786
