Debloating Feature-Rich Closed-Source Windows Software

Feature-rich software programs typically provide many configuration options for users to enable and disable features, or tune feature behaviors. Given the values of configuration options, certain code blocks in a program will become redundant code and never be used. However, the redundant code is still present in the program and thus unnecessarily increases a program's attack surface by allowing attackers to use it as return-oriented programming (ROP) gadgets. Existing code debloating techniques have several limitations: not targeting this type of redundant code, requiring access to program source code or user-provided test inputs. In this paper, we propose a practical code debloating approach, called BinDebloat, to address these limitations. BinDebloat identifies and removes redundant code caused by configuration option values. It does not require user-provided test inputs, or support from program developers, and is designed to work on closed-source programs. It uses static program analysis to identify code blocks that are control-dependent on configuration option values. Given a set of configuration option values, it automatically determines which of such code blocks become redundant and uses static binary rewriting to neutralize these code blocks so that they are removed from the attack surface. We evaluated BinDebloat on closed-source Windows programs and the results show that BinDebloat can effectively reduce a program's attack surface.