Biblio

The timing characteristics of cache, a high-speed storage between the fast CPU and the slow memory, may reveal sensitive information of a program, thus allowing an adversary to conduct side-channel attacks. Existing methods for detecting timing leaks either ignore cache all together or focus only on passive leaks generated by the program itself, without considering leaks that are made possible by concurrently running some other threads. In this work, we show that timing-leak-freedom is not a compositional property: a program that is not leaky when running alone may become leaky when interleaved with other threads. Thus, we develop a new method, named adversarial symbolic execution, to detect such leaks. It systematically explores both the feasible program paths and their interleavings while modeling the cache, and leverages an SMT solver to decide if there are timing leaks. We have implemented our method in LLVM and evaluated it on a set of real-world ciphers with 14,455 lines of C code in total. Our experiments demonstrate both the efficiency of our method and its effectiveness in detecting side-channel leaks.

Anti-reverse engineering is one of the core technologies of software intellectual property protection, prevailing techniques of which are static and dynamic obfuscation. Static obfuscation can only prevent static analysis with code mutation done before execution by compressing, encrypting and obfuscating. Dynamic obfuscation can prevent both static and dynamic analysis, which changes code while being executed. Popular dynamic obfuscation techniques include self-modifying code and virtual machine protection. Despite the higher safety, dynamic obfuscation has its problems: 1) code appear in plain text remains a long time; 2) control flow is exposable; 3) time and space overheads are too big. This paper presents a binary protection scheme using dynamic fine-grained code hiding and obfuscation named dynFCHO. In this scheme, basic blocks to be protected are hidden in original code and will be restored while being executed. Code obfuscation is also implemented additionally to enhance safety. Experiments prove that dynFCHO can effectively resist static and dynamic analysis without destructing original software functions. It can be used on most binary programs compiled by standard compilers. This scheme can be widely used with the advantages of strong protection, light-weight implementation, and good extendibility.