We expect a future where we are surrounded by embedded devices, ranging from Java-enabled cell phones to sensor networks and smart appliances. An adversary can compromise our privacy and safety by maliciously modifying the memory contents of these embedded devices. In this paper, we propose a SoftWare-based ATTestation technique (SWATT) to verify the memory contents of embedded devices and establish the absence of malicious changes to the memory contents. SWATT does not need physical access to the device's memory, yet provides memory content attestation similar to TCG or NGSCB without requiring secure hardware. SWATT can detect any change in memory contents with high probability, thus detecting viruses, unexpected configuration settings, and Trojan Horses. To circumvent SWATT, we expect that an attacker needs to change the hardware to hide memory content changes.We present an implementation of SWATT in off-the-shelf sensor network devices, which enables us to verify the contents of the program memory even while the sensor node is running.
Abstract. This paper presents a protocol called SAKE (Software Attestation for Key Establishment), for establishing a shared key between any two neighboring nodes of a sensor network. SAKE guarantees the secrecy and authenticity of the key that is established, without requiring any prior authentic or secret information in either node. In other words, the attacker can read and modify the entire memory contents of both nodes before SAKE executes. Further, to the best of our knowledge, SAKE is the only protocol that can perform key re-establishment after sensor nodes are compromised, because the presence of the attacker's code in the memory of either protocol participant does not compromise the security of SAKE. Also, the attacker can perform any active or passive attack using an arbitrary number of malicious, colluding nodes. SAKE does not require any hardware modification to the sensor nodes, human mediation, or secure side channels. However, we do assume the setting of a computationally-limited attacker that does not introduce its own computationally powerful nodes into the sensor network. SAKE is based on ICE (Indisputable Code Execution), a primitive we introduce in previous work to dynamically establish a trusted execution environment on a remote, untrusted sensor node.
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