ITR-SY: System Hardening through Security Aware Compilation and Processor Architecture

网络计算机系统容易受到恶意攻击。这些攻击通过将处理器程序计数器（PC）重新指向攻击者的代码来接管对受害计算机系统的控制。本提案探讨了安全感知编译和处理器微架构在防止未经授权的PC修改中的作用。PC妥协的两个最常见的实例来自(1)激活记录中的返回地址和(2)函数指针的损坏。保护PC的基本方法是在任何潜在的PC值（如返回地址或函数指针表项）存储在任何内存位置（如数据或堆空间中的堆栈帧或函数指针表）之前应用编码函数。任何存储器值的读入PC首先必须经过解码功能。受损的PC值只会通过解码功能，因此会使恶意攻击无效。本研究探讨了几种不同的PC编码/解码方案，并评估了这些方案的计算开销及其有效性。本研究计划构建一个强化的Linux系统，gcc编译器和其他公共领域的实用程序，如Apache web服务器，结合建议的返回地址和函数指针保护方案。

Networked computer systems are vulnerable to malicious attack. These attackstry to take over the control of a victim computer system by re-pointing the processor program counter (PC) to the attacker's code. This proposal explores a role for security aware compilation and processor microarchitecture in preventing unauthorized PC modifications. The two most common instances of PC compromise arise from the corruption of (1) the return address in an activation record and (2) function pointers. The basic approach to guarding PC is to apply an encoding function before any potential PC value (such as return address, or function pointer table entry) is stored in any memory location (such as a stack frame or function pointer table in the data or heap space). Any read of a memory value into the PC first has to go through a decoding function. A compromised PC value would go only through the decoding function and hence would render the malicious attack ineffective. This research investigates several variations of PC encoding/decoding schemes and evaluates computational overhead of these schemes and their effectiveness. This research plans to build a hardened Linux system, gcc compiler and other public domain utilities such as Apache web server incorporating the proposed return address and function pointer protection schemes.