PowerDrive: Accurate De-Obfuscation and Analysis of PowerShell Malware
This addresses the challenge of malware analysis for security researchers by providing a comprehensive tool to de-obfuscate PowerShell attacks, though it is incremental as it builds on existing de-obfuscation techniques.
The paper tackles the problem of analyzing obfuscated PowerShell malware by presenting PowerDrive, a multi-stage de-obfuscator that successfully analyzed thousands of attacks and revealed patterns, behavioral models, and malicious domains used by attackers.
PowerShell is nowadays a widely-used technology to administrate and manage Windows-based operating systems. However, it is also extensively used by malware vectors to execute payloads or drop additional malicious contents. Similarly to other scripting languages used by malware, PowerShell attacks are challenging to analyze due to the extensive use of multiple obfuscation layers, which make the real malicious code hard to be unveiled. To the best of our knowledge, a comprehensive solution for properly de-obfuscating such attacks is currently missing. In this paper, we present PowerDrive, an open-source, static and dynamic multi-stage de-obfuscator for PowerShell attacks. PowerDrive instruments the PowerShell code to progressively de-obfuscate it by showing the analyst the employed obfuscation steps. We used PowerDrive to successfully analyze thousands of PowerShell attacks extracted from various malware vectors and executables. The attained results show interesting patterns used by attackers to devise their malicious scripts. Moreover, we provide a taxonomy of behavioral models adopted by the analyzed codes and a comprehensive list of the malicious domains contacted during the analysis.