Breaking Obfuscated .NET Malware with Profiler-Based Dynamic Binary Instrumentation
Lars Wallenborn, Tillmann Werner, Sebastian Walla, Steffen Haas
As malware authors increasingly adopt .NET for its ease of development and stability, they rely on sophisticated obfuscation techniques to thwart analysis. Traditional static deobfuscation approaches often fail against modern protections that incorporate runtime integrity checks. This presentation introduces a framework that leverages .NET profilers to perform dynamic binary instrumentation at the MSIL level. We demonstrate how this approach can bypass dynamic checks in obfuscation schemes, extract encrypted strings, and trace execution flows—all without modifying the original binary. Through real-world case studies and live demonstrations, we show how this technique provides reverse engineers with a powerful new tool to analyze obfuscated .NET malware.