Loki: Hardening Code Obfuscation Against Automated Attacks


Moritz Schloegel, Tim Blazytko, Moritz Contag, Cornelius Aschermann, and Julius Basler, Ruhr-Universität Bochum; Thorsten Holz, CISPA Helmholtz Center for Information Security; Ali Abbasi, Ruhr-Universität Bochum


Software obfuscation is a crucial technology to protect intellectual property and manage digital rights within our society. Despite its huge practical importance, both commercial and academic state-of-the-art obfuscation methods are vulnerable to a plethora of automated deobfuscation attacks, such as symbolic execution, taint analysis, or program synthesis. While several enhanced obfuscation techniques were recently proposed to thwart taint analysis or symbolic execution, they either impose a prohibitive runtime overhead or can be removed in an automated way (e.g., via compiler optimizations). In general, these techniques suffer from focusing on a single attack vector, allowing an attacker to switch to other, more effective techniques, such as program synthesis. In this work, we present Loki, an approach for software obfuscation that is resilient against all known automated deobfuscation attacks. To this end, we use and efficiently combine multiple techniques, including a generic approach to synthesize formally verified expressions of arbitrary complexity. Contrary to state-of-the-art approaches that rely on a few hardcoded generation rules, our expressions are more diverse and harder to pattern match against. We show that even the state-of-the-art approach on Mixed-Boolean Arithmetic (MBA) deobfuscation fails to simplify them. Moreover, Loki protects against previously unaccounted attack vectors such as program synthesis, for which it reduces the success rate to merely 19%. In a comprehensive evaluation, we show that our design incurs significantly less overhead while providing a much stronger protection level compared to existing works.

Open Access Media

USENIX is committed to Open Access to the research presented at our events. Papers and proceedings are freely available to everyone once the event begins. Any video, audio, and/or slides that are posted after the event are also free and open to everyone. Support USENIX and our commitment to Open Access.

@inproceedings {281380,
author = {Moritz Schloegel and Tim Blazytko and Moritz Contag and Cornelius Aschermann and Julius Basler and Thorsten Holz and Ali Abbasi},
title = {Loki: Hardening Code Obfuscation Against Automated Attacks},
booktitle = {31st USENIX Security Symposium (USENIX Security 22)},
year = {2022},
isbn = {978-1-939133-31-1},
address = {Boston, MA},
pages = {3055--3073},
url = {https://www.usenix.org/conference/usenixsecurity22/presentation/schloegel},
publisher = {USENIX Association},
month = aug

Presentation Video