Rascals are always sociable, and the chief sign that a man has any nobility in his character is the little pleasure he takes in others company. Arthur Schopenhauer

Hunting for Nginx Alias Traversals in the wild

Nginx, a versatile web server pivotal to numerous internet infrastructures, has held a dominant market share since its inception in 2004, with widespread adoption across websites and Docker containers. This article delves into the intricacies of Nginx, focusing on the location and alias directives that are central to how Nginx handles specific URLs. We also explore potential vulnerabilities arising from misconfigurations and demonstrate how they can lead to security exploits, drawing on research presented at the BlackHat 2018 conference by Orange Tsai.

The guide further illustrates these points through a thorough examination of popular open-source repositories using GitHub Code Search to identify potential Nginx configuration vulnerabilities. Real-world case studies involving Bitwarden and Google’s HPC Toolkit highlight the significant risk of data exposure if these vulnerabilities are not addressed. Additionally, we introduce NavGix, an automated tool designed to detect these vulnerabilities in a black-box manner, providing comprehensive insights into Nginx’s complexities, vulnerabilities, and potential misconfigurations. Hunting for Nginx Alias Traversals in the wild