Full Report
2025-06-18 • Seqrite • Prashil Moon • win.masslogger Open article on Malpedia
Analysis Summary
# Tool/Technique: Masslogger Fileless Variant
## Overview
This document summarizes findings related to a fileless variant of the Masslogger malware, which propagates using Visual Basic Script (VBS) files (`.VBE`) and utilizes the Windows Registry for persistence and operation, avoiding traditional file drops.
## Technical Details
- Type: Malware family (Variant of Masslogger)
- Platform: Windows
- Capabilities: Information stealing, persistence via registry, spread via VBE/VBS files.
- First Seen: Information not explicitly detailed in the provided context, but reported on 2025-06-18.
## MITRE ATT&CK Mapping
*Note: Specific TIDs are inferred based on descriptions of fileless execution, VBE usage, and registry manipulation.*
- T1566 - Phishing / T1059 - Command and Scripting Interpreter (For VBE execution)
- T1059.003 - Windows Command Shell
- T1059.005 - Visual Basic
- T1547 - Boot or Logon Autostart Execution
- T1547.001 - Registry Run Keys / Startup Folder (Inferred from "Hides in Registry")
## Functionality
### Core Capabilities
- **Propagation:** Spreads specifically via `.VBE` (Visual Basic Script Encoded) files.
- **Execution:** Executes code, likely leveraging VBS capabilities, to achieve initial execution.
- **Persistence:** Hides and maintains persistence through manipulation of the Windows Registry.
### Advanced Features
- **Fileless Operation:** Operates without relying on traditional executable files dropped onto the system, making standard file-based detection more difficult.
- **Registry Hiding:** Utilizes the registry to store or execute malicious components or configurations.
## Indicators of Compromise
- File Hashes: [None provided in context]
- File Names: `.VBE` files used for initial delivery/spread.
- Registry Keys: [Specific keys not provided in context, but registry is used for hiding/persistence]
- Network Indicators: [None provided in context]
- Behavioral Indicators: Execution originating from script hosts invoked by VBE files; anomalous registry modifications related to startup or execution paths.
## Associated Threat Actors
- [Not explicitly mentioned in the context provided, typically associated with financially motivated threat groups]
## Detection Methods
- Signature-based detection: YARA/AV signatures targeting known Masslogger code patterns.
- Behavioral detection: Monitoring for WScript/CScript execution originating from unusual locations, or script execution followed by registry modifications indicative of persistence.
- YARA rules: [Not provided in context]
## Mitigation Strategies
- **Prevention:** Disable or restrict the execution of VBS/VBE files via Group Policy or endpoint security solutions.
- **Hardening:** Implement strict execution policies to prevent unsigned or unknown scripts from running. Monitor and restrict write access to critical registry locations used for persistence.
## Related Tools/Techniques
- Masslogger (Base malware family)
- Other script-based malware utilizing encoded scripts for obfuscation.