Linux Security Summit North America 2017

In many Linux kernel exploits, attackers aim to escalate privilege (obtain uid=0) via vulnerabilities of system calls. In this presentation, we propose a method to prevent privilege escalation attacks. The basic design, implementation, evaluation results and limitations are discussed.

Our method focusses on the feature that privileges of process is changed only in particular system call processing, and monitors the changes of privileges by each system call to prevent privilege escalation attacks. The watched privileges include not only those related to DAC(such as uid), but also includes important valuables of MAC system such as SELinux (e.g: selinux_enforcing). The method is implemented as a patch for Linux kernel and evaluated. It is found that privilege escalation can be prevented in real vulnerabilities, and the performance overhead is pretty small.