Security Researcher Reverses BattlEye's BEDaisy.sys Kernel Anti-Cheat Driver Through Static Analysis
Key Takeaways
- ▸BEDaisy.sys employs code virtualization, likely through a customized VMProtect implementation, with VM bytecode stored in a 7.4MB .be0 section rather than native executable code
- ▸The kernel driver uses minifilter-based filesystem monitoring, debugger detection, and multiple anti-analysis techniques to protect against reverse engineering
- ▸BattlEye's driver loads on-demand when protected games launch and unloads when they exit, differing from boot-time loading approaches used by competitors like Riot's Vanguard
Summary
A security researcher has published an in-depth technical analysis of BEDaisy.sys, the kernel-level anti-cheat driver used by BattlEye in popular games including PUBG, Rainbow Six Siege, DayZ, and Escape from Tarkov. The analysis reveals that the 7.9MB driver employs sophisticated obfuscation techniques, including code virtualization via what appears to be a heavily customized VMProtect build, debugger detection, and minifilter-based filesystem monitoring to prevent cheating. The researcher conducted both static and dynamic analysis to extract and document the driver's internals, uncovering its architectural patterns and protection mechanisms.
The study demonstrates that BEDaisy.sys uses an unusual PE structure with a tiny 100KB .text section paired with a massive 7.4MB custom .be0 section containing virtualized bytecode rather than native x86-64 instructions. This design choice reflects enterprise-grade security measures typical of production anti-cheat systems deployed across competitive multiplayer games. While the analysis is not a complete reverse engineering—given the scope and complexity of the obfuscated codebase—it provides valuable documentation of the methodology, protections encountered, and specific technical findings that advance the understanding of kernel-level anti-cheat implementations.
- The analysis reveals that commercial anti-cheat vendors routinely customize security tooling with custom section names and stripped identifiers to obscure the underlying protection mechanisms
