Less is More: Supporting Developers in Vulnerability Detection during Code Review

TL;DR

This study demonstrates that explicitly instructing developers to focus on security during code review significantly increases vulnerability detection, while providing a security checklist does not yield additional benefits.

Contribution

It provides empirical evidence that mental attitude influences vulnerability detection and evaluates the impact of security checklists in code review.

Findings

Focusing on security increases vulnerability detection by eight times.

Security checklists do not significantly improve vulnerability detection.

Most reviewers have three or more years of professional experience.

Abstract

Reviewing source code from a security perspective has proven to be a difficult task. Indeed, previous research has shown that developers often miss even popular and easy-to-detect vulnerabilities during code review. Initial evidence suggests that a significant cause may lie in the reviewers' mental attitude and common practices. In this study, we investigate whether and how explicitly asking developers to focus on security during a code review affects the detection of vulnerabilities. Furthermore, we evaluate the effect of providing a security checklist to guide the security review. To this aim, we conduct an online experiment with 150 participants, of which 71% report to have three or more years of professional development experience. Our results show that simply asking reviewers to focus on security during the code review increases eight times the probability of vulnerability detection. The presence of a security checklist does not significantly improve the outcome further, even when the checklist is tailored to the change under review and the existing vulnerabilities in the change. These results provide evidence supporting the mental attitude hypothesis and call for further work on security checklists' effectiveness and design. Data and materials: https://doi.org/10.5281/zenodo.6026291