FirmXRay: Detecting Bluetooth Link Layer Vulnerabilities From Bare-Metal Firmware

Today, Bluetooth 4.0, also known as Bluetooth Low Energy (BLE), has been widely used in many IoT devices (e.g., smart locks, smart sensors, and wearables). However, BLE devices could contain a number of vulnerabilities at the BLE link layer during broadcasting, pairing, and message transmission. To detect these vulnerabilities directly from the bare-metal firmware, we present FirmXRay, the first static binary analysis tool with a set of enabling techniques including a novel base address identification algorithm for robust firmware disassembling, precise data structure recognition, and configuration value resolution. As a proof-of-concept, we focus on the BLE firmware from two leading SoC vendors (i.e., Nordic and Texas Instruments), and implement a prototype of FirmXRay atop Ghidra. We have evaluated FirmXRay with 793 unique firmware (corresponding to 538 unique devices) collected using a mobile app based approach, and our experiment results show that 98.1% of the devices have configured random static MAC addresses, 71.5% Just Works pairing, and 98.5% insecure key exchanges. With these vulnerabilities, we demonstrate identity tracking, spoofing, and eavesdropping attacks on real-world BLE devices.