Comparative evaluation of approaches & tools for effective security testing of Web applications

It is generally accepted that adopting both static application security testing (SAST) and dynamic application security testing (DAST) approaches is vital for thorough and effective security testing. However, this suggestion has not been comprehensively evaluated, especially with regard to the individual risk categories mentioned in Open Web Application Security Project (OWASP) Top 10:2021 and common weakness enumeration (CWE) Top 25:2023 lists. Also, it is rare to find any evidence-based recommendations for effective tools for detecting vulnerabilities from a specific risk category or severity level. These shortcomings increase both the time and cost of systematic security testing when its need is heightened by increasingly frequent and preventable incidents. This study aims to fill these gaps by empirically testing seventy-five real-world Web applications using four SAST and five DAST tools. Only popular, free, and open-source tools were selected and each Web application was scanned using these nine tools. From the report generated by these tools, we considered two parameters to measure effectiveness: count and severity of the vulnerability found. We also mapped the vulnerabilities to OWASP Top 10:2021 and CWE Top 25:2023 lists. Our results show that using only DAST tools is the preferred option for four OWASP Top 10:2021 risk categories while using only SAST tools is preferred for only three risk categories. Either approach is effective for two of the OWASP Top 10:2021 risk categories. For CWE Top 25:2023 list, all three approaches were equally effective and found vulnerabilities belonging to three risk categories each. We also found that none of the tools were able to detect any vulnerability in one OWASP Top 10:2021 risk category and in eight CWE Top 25:2023 categories. This highlights a critical limitation of popular tools. The most effective DAST tool was OWASP Zed Attack Proxy (ZAP), especially for detecting vulnerabilities in broken access control, insecure design, and security misconfiguration risk categories. Yasca was the best-performing SAST tool, and outperformed all other tools at finding high-severity vulnerabilities. For medium-severity and low-severity levels, the DAST tools Iron Web application Advanced Security testing Platform (WASP) and Vega performed better than all the other tools. These findings reveal key insights, such as, the superiority of DAST tools for detecting certain types of vulnerabilities and the indispensability of SAST tools for detecting high-severity issues (due to detailed static code analysis). This study also addresses significant limitations in previous research by testing multiple real-world Web applications across diverse domains (technology, health, and education), enhancing generalization of the findings. Unlike studies that rely primarily on proprietary tools, our use of open-source SAST and DAST tools ensures better reproducibility and accessibility for organizations with limited budget.