PowerDrive: Accurate De-Obfuscation and Analysis of PowerShell Malware

TL;DR

PowerDrive is a comprehensive open-source tool that effectively de-obfuscates PowerShell malware, enabling detailed analysis of attack patterns, malicious behaviors, and contact domains, thus aiding cybersecurity defenses.

Contribution

It introduces a novel multi-stage de-obfuscator for PowerShell malware that combines static and dynamic analysis, filling a gap in existing malware analysis tools.

Findings

PowerDrive successfully analyzed thousands of PowerShell attacks.

It revealed common obfuscation patterns used by attackers.

The tool identified malicious domains contacted during attacks.

Abstract

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.