[corCTF 2022] CoRJail: From Null Byte Overflow To Docker Escape Exploiting poll_list Objects In The Linux Kernel
CoRJail is a kernel exploitation challenge designed for corCTF 2022. Players were asked to escape from a hardened Docker container with custom seccomp filters exploiting a Off-By-Null vulnerability in a Linux Kernel Module accessible via procfs. With this article, I present a novel kernel exploitation technique I originally used in the Google kCTF Vulnerability Reward Program to compromise Google’s hardened Kubernetes infrastructure, escaping from a nsjail and gaining root privileges on a Container Optimized OS. Let’s get started!