Metadata

Year	2020
Target	Binary
Technique	Symbolic
Guarantees	sound with restrictions
Available	yes
Repository	https://github.com/binsec/binsec
Website	https://binsec.github.io/
Paper1	BINSEC: Binary Code Analysis with Low-Level Regions
Paper2	Binsec/Rel: Efficient relational symbolic execution for constant-time at binary-level
Tutorial	yes

Binsec/Rel is a static analysis tool that works on the binary level, thereby overcoming issues of compilers inserting non-constant-time code or turning constant-time code into non-constant-time one. First developed as the Binsec/Rel extension to the Binsec tool, later integrated into the Binsec tool directly. See more at the CT-checking docs.

Abstract

The constant-time programming discipline (CT) is an efficient countermeasure against timing side-channel attacks, requiring the control flow and the memory accesses to be independent from the secrets. Yet, writing CT code is challenging as it demands to reason about pairs of execution traces (2-hypersafety property) and it is generally not preserved by the compiler, requiring binary-level analysis. Unfortunately, current verification tools for CT either reason at higher level (C or LLVM), or sacrifice bug-finding or bounded-verification, or do not scale. We tackle the problem of designing an efficient binary-level verification tool for CT providing both bug-finding and bounded-verification. The technique builds on relational symbolic execution enhanced with new optimizations dedicated to information flow and binary-level analysis, yielding a dramatic improvement over prior work based on symbolic execution. We implement a prototype, BINSEC/REL, and perform extensive experiments on a set of 338 cryptographic implementations, demonstrating the benefits of our approach in both bug-finding and bounded-verification. Using BINSEC/REL, we also automate a previous manual study of CT preservation by compilers. Interestingly, we discovered that gcc -O0 and backend passes of clang introduce violations of CT in implementations that were previously deemed secure by a state-of-the-art CT verification tool operating at LLVM level, showing the importance of reasoning at binary-level.