The kernel of HarmonyOS 4.2 has a defense capability against user-mode attack surfaces comparable to that of native Android 14, One UI 6, and iOS 17 operating system kernels, all of which deploy mature security defense mechanisms. At present, the main way of kernel attack is still to use memory corruption vulnerability to escalate privilege through kernel data reading and writing and kernel code execution. The HarmonyOS 4.2 kernel is similar to the native Android 14 and ONE UI 6 kernel, and there is no strict permission isolation between major kernel modules, while iOS is based on a hybrid kernel architecture of Mach and BSD.