InternalBlue - Bluetooth Binary Patching and Experimentation Framework (1905.00631v1)

Abstract: Bluetooth is one of the most established technologies for short range digital wireless data transmission. With the advent of wearables and the Internet of Things (IoT), Bluetooth has again gained importance, which makes security research and protocol optimizations imperative. Surprisingly, there is a lack of openly available tools and experimental platforms to scrutinize Bluetooth. In particular, system aspects and close to hardware protocol layers are mostly uncovered. We reverse engineer multiple Broadcom Bluetooth chipsets that are widespread in off-the-shelf devices. Thus, we offer deep insights into the internal architecture of a popular commercial family of Bluetooth controllers used in smartphones, wearables, and IoT platforms. Reverse engineered functions can then be altered with our InternalBlue Python framework---outperforming evaluation kits, which are limited to documented and vendor-defined functions. The modified Bluetooth stack remains fully functional and high-performance. Hence, it provides a portable low-cost research platform. InternalBlue is a versatile framework and we demonstrate its abilities by implementing tests and demos for known Bluetooth vulnerabilities. Moreover, we discover a novel critical security issue affecting a large selection of Broadcom chipsets that allows executing code within the attacked Bluetooth firmware. We further show how to use our framework to fix bugs in chipsets out of vendor support and how to add new security features to Bluetooth firmware.

• The paper presents InternalBlue, a Python-based framework enabling researchers to analyze and binary patch lower-level Bluetooth protocols on Broadcom chipsets using reverse engineering.
• A critical discovery using InternalBlue was a severe remote code execution vulnerability (CVE-2018-19860) in Broadcom firmware, subsequently reported and patched.
• InternalBlue facilitates practical security testing like Niño attacks and ECDH exploits, revealing issues such as insufficient insecure pairing warnings and providing a platform for patching legacy devices.

Analysis of Bluetooth Binary Patching and Intrusion Frameworks

The paper "InternalBlue -- Bluetooth Binary Patching and Experimentation Framework" presents a thorough examination and implementation of a Python-based research framework designed for scrutinizing Bluetooth protocol layers beneath the Host Controller Interface (HCI) in Broadcom Bluetooth chipsets. The authors focus their investigation on multiple off-the-shelf devices, primarily involving the Nexus 5 smartphone and other Broadcom-connected hardware.

Technical Overview

Bluetooth has become a significant technology in the field of IoT, promoting further research into security and optimization protocols. Despite its extensive utilization, comprehensive statistical tools for analyzing Bluetooth remain underdeveloped compared to Wi-Fi technology. The researchers address this deficit by reverse engineering Broadcom chipsets to allow direct modification of lower-level protocol layers and firmware memory. This framework avoids costly proprietary equipment and provides an accessible solution to monitor and manipulate Bluetooth protocols, enabling novel insights into the internal structure of Bluetooth chipsets.

Numerical Results and Findings

A critical discovery made through this paper is a severe vulnerability within the Broadcom firmware (CVE-2018-19860), allowing unauthenticated execution of functions. This bug is attributed to improper bounds checking in handler tables, permitting remote code execution on numerous Broadcom Bluetooth chips. The vulnerability has been reported to Broadcom, resulting in security patches being deployed.

The authors demonstrate the capability of InternalBlue to perform various security tests, such as the Niño attack and others involving elliptic Diffie-HeLLMan (ECDH) pairing exploits. They provide evidence on the practicality of sending arbitrary Link Manager Protocol (LMP) packets and conducting accurate security evaluations on connected devices without revealing their existence. On several tested devices, it was confirmed that neither Android nor iOS provides sufficient user warnings regarding insecure pairing. Moreover, they noted that the modified LMP handler and packet manipulation could successfully disrupt Bluetooth operations and affect wireless coexistence with Wi-Fi signals.

Implications and Future Directions

This research has direct implications for the future of Bluetooth security and device evaluation frameworks. It underscores the necessity for greater scrutiny of lower-layer protocols, which traditionally have been overshadowed by higher layers in terms of security. By promoting the accessibility and customization of Bluetooth binary patching via InternalBlue, the authors lay groundwork for future tools and methodologies aimed at bridging gaps in Bluetooth protocol analysis.

The paper recommends adopting InternalBlue as a platform-enhancing Bluetooth security for legacy devices by providing custom patches to address known vulnerabilities when vendor support ceases. Moreover, it emphasizes the importance of further exploration into PHY layer modifications, advocating for the integration of new Bluetooth version functionalities before their official release.

Conclusion

InternalBlue advances the capability of network researchers to conduct detailed analyses of Bluetooth operations on consumer-grade devices, presenting significant insights into unnoticed firmware vulnerabilities. By facilitating modifications and providing a practical research approach, the framework opens new avenues for investigative and practical applications in the field of wireless communication protocols. While the paper thoroughly examines InternalBlue’s implications, it invites further community collaboration and code contributions to bolster security across various IoT-enabled environments.