The root privilege escalation attack is extremely destructive to the security of the Android system. SEAndroid implements mandatory access control to the system through the SELinux security policy at the kernel mode, making the general root privilege escalation attacks unenforceable. However, malicious attackers can exploit the Linux kernel vulnerability of privilege escalation to modify the SELinux security labels of the process arbitrarily to obtain the desired permissions and undermine system security. Therefore, investigating the protection method of the security labels in the SELinux kernel is urgent. And the impact on the existing security configuration of the system must also be reduced. This paper proposes an optimization scheme of the SELinux mechanism based on security label randomization to solve the aforementioned problem. At the system runtime, the system randomizes the mapping of the security labels inside and outside the kernel to protect the privileged security labels of the system from illegal obtainment and tampering by attackers. This method is transparent to users; therefore, users do not need to modify the existing system security configuration. A tamper-proof detection method of SELinux security label is also proposed to further improve the security of the method. It detects and corrects the malicious tampering behaviors of the security label in the critical process of the system timely. The above methods are implemented in the Linux system, and the effectiveness of security defense is proven through theoretical analysis and experimental verification. Numerous experiments show that the effect of this method on system performance is less than 1%, and the success probability of root privilege escalation attack is less than 10⁻⁹.

中文翻译：

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SLR-SELinux：通过安全标签随机化增强SEAndroid的安全基础

根特权升级攻击对Android系统的安全性具有极大的破坏性。SEAndroid在内核模式下通过SELinux安全策略实现对系统的强制访问控制，从而使常规的根特权升级攻击无法执行。但是，恶意攻击者可以利用特权升级的Linux内核漏洞来任意修改进程的SELinux安全标签，以获得所需的权限并破坏系统安全性。因此，迫切需要研究SELinux内核中安全标签的保护方法。并且还必须减少对系统现有安全配置的影响。针对上述问题，提出了一种基于安全标签随机化的SELinux机制优化方案。在系统运行时，系统会随机化内核内部和外部的安全标签映射，以保护系统的特权安全标签免遭攻击者的非法获取和篡改。该方法对用户透明；因此，用户不需要修改现有的系统安全配置。还提出了一种SELinux安全标签的防篡改检测方法，以进一步提高该方法的安全性。它可以在系统的关键过程中及时检测并纠正安全标签的恶意篡改行为。以上方法均在Linux系统中实现，通过理论分析和实验验证证明了安全防御的有效性。大量实验表明，该方法对系统性能的影响小于1％，^-9。