Recam Redux – DeConfusing ConfuserEx
This report shows how to deobfuscate a custom .NET ConfuserEx protected malware. We identified this recent malware campaign from our Advanced Malware Protection (AMP) telemetry. Initial infection is via a malicious Word document, the malware ultimately executes in memory an embedded payload from the Recam family. Recam is an information stealer. Although the malware has been around for the past few years, there’s a reason you won’t see a significant amount of documentation concerning its internals. The authors have gone the extra mile to delay analysis of the sample, including multiple layers of data encryption, string obfuscation, piecewise nulling, and data buffer constructors. It also relies on its own C2 binary protocol which is heavily encrypted along with any relevant data before transmission.