Embedded Systems Security 2

06 April 2017, 14:00, A6-004

Session chair: Michail Maniatakos, New York University Abu Dhabi, United Arab Emirates

DRIVE: Dynamic Runtime Integrity Verification and Evaluation

Andre Rein

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Classic security techniques use patterns (e.g., virus scanner) for detecting malicious software, compiler features (e.g., canaries, tainting) or hardware memory protection features (e.g., DEP) for protecting software. An alternative approach is the verification of software based on the comparison between the binary code loaded before runtime and the actual memory image during runtime. The expected memory image is predictable based on the ELF-file, the loading mechanism, and its allocated memory addresses. Using binary files as references for verifying the memory during execution allows for the definition of white-lists based on the actual software used. This enables a novel way of detecting sophisticated attacks to executed code, which is not considered by current approaches. This paper presents the background, design, implementation, and verification of a non-intrusive runtime memory verification concept, which is based on the comparison of binary executables and the actual memory image.

An Attack Against Message Authentication in the ERTMS Train to Trackside Communication Protocols

Tom Chothia, Mihai Ordean, Joeri de Ruiter, Richard Thomas

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This paper presents the results of a cryptographic analysis of the protocols used by the European Rail Traffic Management System (ERTMS). A stack of three protocols secures the communication between trains and trackside equipment; encrypted radio communication is provided by the GSM-R protocol, on top of this the EuroRadio protocol provides authentication for a train control application-level protocol. We present an attack which exploits weaknesses in all three protocols: GSM-R has the same well known weaknesses as the GSM protocol, and we present a new collision attack against the EuroRadio protocol. Combined with design weaknesses in the application-level protocol, these vulnerabilities allow an attacker, who observes a MAC collision, to forge train control messages. We demonstrate this attack with a proof of concept using train control messages we have generated ourselves. Currently, ERTMS is only used to send small amounts of data for short sessions, therefore this attack does not present an immediate danger. However, if EuroRadio was to be used to transfer larger amounts of data trains would become vulnerable to this attack. Additionally, we calculate that, under reasonable assumptions, an attacker who could monitor all backend control centres in a country the size of the UK for 45 days would have a 1% chance of being able to take control of a train.

Using Program Analysis to Synthesize Sensor Spoofing Attacks

Ivan Pustogarov, Thomas Ristenpart, Vitaly Shmatikov, Ivan Pustogarov

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In a sensor spoofing attack, an adversary modifies the physical environment in a certain way so as to force an embedded system into unwanted or unintended behaviors. This usually requires a thorough understanding of the system’s control logic. The conventional methods for discovering this logic are manual code inspection and experimentation. In this paper, we design a directed, compositional symbolic execution framework that targets software for the popular MSP430 family of microcontrollers. Using our framework, an analyst can generate traces of sensor readings that will drive an MSP430-based embedded system to a chosen point in its code. As a case study, we use our system to generate spoofed wireless signals used as sensor inputs into AllSee, a recently proposed low-cost gesture recognition system. We then experimentally confirm that AllSee recognizes our adversarially synthesized signals as “gestures.”

SCM: Secure Code Memory Architecture

Ruan de Clercq, Ronald De Keulenaer, Pieter Maene, Bjorn De Sutter, Bart Preneel, Ingrid Verbauwhede

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An increasing number of applications implemented on a SoC (System-on-chip) require security features. This work addresses the issue of protecting the integrity of code and read-only data that is stored in memory. To this end, we propose a new architecture called SCM, which works as a standalone IP core in a SoC. To the best of our knowledge, there exists no architectural elements similar to SCM that offer the same strict security guarantees while, at the same time, not requiring any modifications to other IP cores in its SoC design. In addition, SCM has the flexibility to select the parts of the software to be protected, which eases the integration of our solution with existing software. The evaluation of SCM was done on the Zynq platform which features an ARM processor and an FPGA. The design was evaluated by executing a number of different benchmarks from memory protected by SCM, and we found that it introduces minimal overhead to the system.