SWATT: software-based attestation for embedded devices

TLDR

Embedded devices are ubiquitous, yet adversaries can compromise privacy and safety by maliciously modifying their memory contents. The paper proposes SWATT, a software‑based attestation technique to verify embedded device memory and detect malicious modifications. SWATT achieves this without physical memory access, offering attestation comparable to TCG or NGSCB, and is implemented on off‑the‑shelf sensor network devices to verify program memory while the node operates. SWATT detects any memory change with high probability, identifying viruses, misconfigurations, and Trojan horses, and an attacker would need to alter hardware to evade detection.

Abstract

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.