Unmasking a Multi-Stage Loader: AutoIt Abuse Leading to Vidar Stealer Command-and-Control Communication
Essential information
- Published
- 11/05/2026 11:49
- Modified
- 11/05/2026 19:27
- Tags
- 2026-05-11 anti-analysis arkei autoit c2 communication credential-theft defense evasion information stealer multi-stage loader vidar
- Related entities
- 5 observables, 20 techniques (mitre), 2 malware, 2 others
Description
A sophisticated multi-stage infection chain was identified through proactive threat hunting, beginning with the execution of MicrosoftToolkit.exe, a commonly abused hack tool. The attack employed file masquerading techniques, renaming a .dot file to .bat format to evade detection. The malware performed process discovery and attempted to terminate security-related processes before extracting payloads using extract32.exe. An AutoIt-compiled executable (Replies.scr) functioned as a loader, processing an external encrypted payload file and establishing command-and-control communication with infrastructure associated with Vidar Stealer. The malware demonstrated advanced anti-analysis capabilities, including debugger detection and instrumentation callback queries. It targeted credentials, browser data, cryptocurrency wallets, and system information. Post-execution cleanup routines deleted artifacts and terminated processes to minimize forensic evidence and evade detection, significantly complicating incident res...