Since Edge introduced the win32k filter mechanism, the way of escaping the sandbox from kernel is getting narrower and narrower. In fact, on the latest win10 rs4, most types of GDI objects could not be created in the content process of Edge. In addition, the type isolation makes it very difficult to exploit a win32k bug. This is a huge challenge for breaking Edge sandbox now. However, Edge allows us to access the direct x kernel from the unfiltered syscall functions.Last year, Tencent ZhanluLab began to study the Direct X subsystem, and we discovered 10+ bugs in few months. In the first part of this talk, we start with an overview of direct x subsystem and discuss how to analyze its interfaces and internal objects. After that, we explain three bugs representing three typical security flaws. Among the vulnerabilities we discovered, a few of them are very interesting, and it is a bit special to exploit them. We successfully leverage a vulnerability to break the Edge and escalate privilege to system. We will disclose all the details of this exploit in the second part of this talk.