In our very first blogpost about VulHunt, we’ve explained what is the problem our framework solves, how it differs from common approaches to detect vulnerabilities in binaries, and introduced you to our framework’s core capabilities. As we previously discussed, VulHunt has two usage modes: standalone and agentic. In this blogpost, we’ll focus on the standalone mode, which works with VulHunt rules – Lua language scripts that interact with the core engine to detect vulnerabilities.We’ll guide you through the process of writing a VulHunt rule for a known vulnerability in Rsync, a popular tool to transfer files over the network present in many systems. We start by understanding the vulnerability before proceeding to how we can use VulHunt to detect the exact point in the code where the vulnerability occurs.