An Investigation of Hardware Security Bug Characteristics in Open-Source Projects

TL;DR

This study analyzes hardware security bugs in open-source projects, revealing their characteristics, impact, and fix patterns to improve security practices and detection techniques.

Contribution

It provides a detailed classification and analysis of hardware security bugs in OpenTitan, highlighting their properties and proposing an AST-based analysis method.

Findings

53% of bugs have security implications

55% of bug fixes modify only one file

Security bugs are highly localized in code

Abstract

Hardware security is an important concern of system security as vulnerabilities can arise from design errors introduced throughout the development lifecycle. Recent works have proposed techniques to detect hardware security bugs, such as static analysis, fuzzing, and symbolic execution. However, the fundamental properties of hardware security bugs remain relatively unexplored. To gain a better understanding of hardware security bugs, we perform a deep dive into the popular OpenTitan project, including its bug reports and bug fixes. We manually classify the bugs as relevant to functionality or security and analyze characteristics, such as the impact and location of security bugs, and the size of their bug fixes. We also investigate relationships between security impact and bug management during development. Finally, we propose an abstract syntax tree-based analysis to identify the syntactic characteristics of bug fixes. Our results show that 53% of the bugs in OpenTitan have potential security implications and that 55% of all bug fixes modify only one file. Our findings underscore the importance of security-aware development practices and tools and motivate the development of techniques that leverage the highly localized nature of hardware bugs.