LoadLord: Loading on the Fly to Defend Against Code-Reuse Attacks

Code-reuse attacks have become a kind of common attack method, in which attackers use the existing code in the program to hijack the control flow. Most existing defenses focus on control flow integrity (CFI), code randomization, and software debloating. However, most fine-grained schemes of those that ensure such high security suffer from significant performance overhead, and only reduce attack surfaces such as software debloating can not defend against code-reuse attacks completely. In this paper, from the perspective of shrinking the available code space at runtime, we propose LoadLord, which dynamically loads, and timely unloads functions during program running to defend against code-reuse attacks. LoadLord can reduce the number of gadgets in memory, especially high-risk gadgets. Moreover, LoadLord ensures the control flow integrity of the loading process and breaks the necessary conditions to build a gadget chain. We implemented LoadLord on Linux operating system and experimented that when limiting only 1/16 of the original function. As a result, LoadLord can defend against code-reuse attacks and has an average runtime overhead of 1.7% on the SPEC CPU 2006, reducing gadgets by 94.02%.