Lockdown: Dynamic Control-Flow Integrity

TL;DR

Lockdown is a dynamic control-flow integrity system that protects legacy binaries by adaptively learning control-flow graphs and enforcing fine-grained security checks with minimal performance impact.

Contribution

It introduces a dynamic CFI approach that works on binary-only applications by leveraging trusted dynamic loader information.

Findings

Low performance overhead demonstrated in prototype

Protects legacy binaries without source code modifications

Enforces fine-grained control-flow restrictions

Abstract

Applications written in low-level languages without type or memory safety are especially prone to memory corruption. Attackers gain code execution capabilities through such applications despite all currently deployed defenses by exploiting memory corruption vulnerabilities. Control-Flow Integrity (CFI) is a promising defense mechanism that restricts open control-flow transfers to a static set of well-known locations. We present Lockdown, an approach to dynamic CFI that protects legacy, binary-only executables and libraries. Lockdown adaptively learns the control-flow graph of a running process using information from a trusted dynamic loader. The sandbox component of Lockdown restricts interactions between different shared objects to imported and exported functions by enforcing fine-grained CFI checks. Our prototype implementation shows that dynamic CFI results in low performance overhead.