Event

16:00
-
17:00

Day 1

What the PHUZZ?! Finding 0-days in Web Applications with Coverage-guided Fuzzing

Recorded

Security

PHUZZ is a framework for Coverage-Guided Fuzzing of PHP Web Applications Fuzz testing is an automated approach to vulnerability discovery. Coverage-guided fuzz testing has been extensively researched in binary applications and the domain of memory corruption vulnerabilities. However, many web vulnerability scanners still rely on black-box fuzzing (e.g., predefined sets of payloads or basic heuristics), which severely limits their vulnerability detection capabilities. In this talk, we present our academic fuzzing framework, "PHUZZ," and the challenges we faced in bringing coverage-guided fuzzing to PHP web applications. Our experiments show that PHUZZ outperforms related works and state-of-the-art vulnerability scanners in discovering seven different vulnerability classes. Additionally, we demonstrate how PHUZZ uncovered over 20 potential security issues and two 0-day vulnerabilities in a large-scale fuzzing campaign of the most popular WordPress plugins.

The World Wide Web has become a fundamental part of modern society, providing crucial services such as social networks, online shopping, and other web applications. To this day, web vulnerabilities continue to be discovered, and data breaches are reported, even on high-profile websites. While several viable methods exist to detect web vulnerabilities, such as penetration tests, source code reviews, and bug bounty programs, these approaches are typically costly and time-intensive. Therefore, discovering web vulnerabilities in an automated and cost-effective fashion is desirable.

One method to approach this problem is coverage-guided "fuzzing", which has been successfully used to identify memory corruption bugs in binary applications, but has seen limited application to web applications. Our academic research has resulted in an open-source prototype called "PHUZZ," which outperforms classic black-box vulnerability scanners in detecting web vulnerabilities with its fuzzing approach.

This talk will first introduce the concept of coverage-guided fuzzing and the differences from black-box web fuzzing performed by vulnerability scanners. After diving into the challenges of applying coverage-guided fuzzing to web applications, we will introduce PHUZZ and explain how its approach allows the detection of a wide variety of web vulnerabilities, including SQLi, RCE, XSS, XXE, open redirection, insecure deserialization, and path traversal in PHP web applications.

Our comparison of PHUZZ with state-of-the-art black-box vulnerability scanners, using a diverse set of artificial and real-world web applications containing known and unknown vulnerabilities, showed surprising results. Not only does PHUZZ outperform the other vulnerability scanners in the number of discovered vulnerabilities, but it also discovers over a dozen new potential vulnerabilities and two 0-days, which we will discuss in our talk. Finally, we will motivate the use of PHUZZ [1] and coverage-guided fuzzing methods to discover web vulnerabilities.

This presentation is based on our academic publication "What All the PHUZZ Is About: A Coverage-guided Fuzzer for Finding Vulnerabilities in PHP Web Applications" [0].

[0] https://dl.acm.org/doi/10.1145/3634737.3661137 [1] https://github.com/gehaxelt/phuzz