An Empirical Analysis of ReDoS Vulnerabilities and ReDoS Detection Tools

ReDoS vulnerabilities are a type of denial of service software weakness that occurs when a regex is used to validate user-supplied input. In some cases, the regex matching process can take exponential time, leading to a denial of service. In this study, we examine and compare the effectiveness of five publicly-available regex detection tools, and one regex correction tool, using three datasets. We further perform an empirical analysis of all ReDoS vulnerabilities reported to the NVD database in order to understand how they differ from non-ReDoS vulnerabilities and glean insights about this type of weakness. We find that ReDoS vulnerabilities are becoming more prevalent and are much more likely to be exploited than non-ReDoS vulnerabilities. We further find that detection tools exhibit substantial disagreement on whether or not a given regex is vulnerable.