Hard Edges: Hardware-Based Control-Flow Integrity for Embedded Devices

Control-Flow Integrity (CFI) is a popular technique to defend against State-of-the-Art exploits, by ensuring that every (indirect) control-flow transfer points legitimate address and it part of the Control-flow Graph (CFG) program. Enabling CFI in real systems not straightforward, since many cases actual CFG program can only be approximated. Even case where there perfect knowledge CFG, all return instructions will their call sites, without employing shadow stack, questionable.In this work, we explore implementation full-featured CFI-enabled Instruction Set Architecture (ISA) on hardware. Our new provide finest possible granularity for both intra-function inter-function Integrity. We implement hardware-based (HCFI) modifying SPARC SoC evaluate prototype an FPGA board running SPECInt benchmarks instrumented with fine-grained policy. HCFI effectively protect applications from code-reuse attacks, while adding less than 1% average runtime 2% power consumption overhead, making particularly suitable embedded systems.