Description

A sophisticated multi-stage malware campaign delivering the Vidar Infostealer has been uncovered, leveraging AutoIt scripting, file masquerading, and legitimate online platforms to evade detection and steal sensitive user data. The infection begins when victims execute MicrosoftToolkit(EXE), a commonly abused software activation utility distributed through unofficial sources. Rather than exploiting vulnerabilities, the attackers rely on users willingly launching the malicious file, initiating a stealthy staged infection chain designed to harvest browser credentials, cookies, cryptocurrency wallets, and system information. Once executed, the malware launches cmd(EXE)and renames a disguised file, swingers.dot, into a batch script to bypass simple security controls. It then performs reconnaissance using built-in Windows utilities such as tasklist(EXE) and findstr(EXE) to identify active processes and potential security tools. Additional payloads are extracted using extract32(EXE) before executing an AutoIt-compiled loader named Replies.scr. Functioning as a staged loader, the AutoIt component decrypts and rebuilds an external payload directly in memory before deploying the Vidar stealer, allowing the malicious activity to blend seamlessly with legitimate automation processes. To evade analysis, the malware employs anti-debugging and anti-EDR techniques using ZwQueryInformationProcess to detect debugger presence and instrumentation callbacks. Once active, Vidar establishes command-and-control communication through WinINet APIs and abuses trusted platforms like Telegram and Steam Community for configuration retrieval and staging instructions. This tactic allows malicious traffic to blend with normal web activity, making network-level detection significantly harder. Researchers also observed suspicious DNS resolution activity through public Google DNS infrastructure. After data exfiltration, the malware deletes dropped files, removes execution artifacts, frees memory structures, and terminates itself using RtlExitUserProcess to reduce forensic evidence. Organizations are advised to isolate affected systems immediately, reset all potentially exposed credentials, enforce MFA, monitor for suspicious outbound traffic and unauthorized scripting activity. Proactive threat hunting, behavioral detection, and strict application control policies remain critical defenses against evolving multi-stage infostealer campaigns like Vidar.