In this lab walkthrough, we dive into the analysis of AsyncRAT, a sophisticated piece of malware designed for remote access and control of compromised systems. AsyncRAT is notorious for its multi-layered obfuscation, use of external resources for payload delivery, and persistence mechanisms that enable it to evade detection and maintain control over infected hosts. The malware employs various techniques to conceal its operations, including script obfuscation, string manipulation, steganography, and dynamic code execution
The challenge begins with examining an initial JavaScript file, which acts as the first stage of the infection chain. This script decodes and delivers a PowerShell payload, which then progresses to downloading and processing subsequent stages. Each stage involves intricate methods for extracting and executing payloads, often hidden within seemingly benign files such as images. These stages illustrate the modular nature of AsyncRAT and highlight its ability to adapt to different environments and objectives.
Throughout the lab, we explore key concepts such as persistence via Windows registry modifications, decoding obfuscated strings, and analyzing hidden data embedded in downloaded files. Using tools like dnSpy, CyberChef, and Powershell commands, we uncover the layers of this malware’s operation. By systematically dissecting each stage, we gain valuable insights into the tactics and techniques employed by AsyncRAT, enhancing our ability to detect, mitigate, and respond to such threat