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Malware

New Vilsa Stealer Malware Infiltrates Systems and Steals Sensitive Data

Cybersec Sentinel

• 2 min read
New Vilsa Stealer Malware Infiltrates Systems and Steals Sensitive Data

Threat Group: - Unknown
Threat Type: - Information Stealer
Exploited Vulnerabilities: - Virtual Machine Detection, Browser Data Extraction, Cryptocurrency Wallets
Malware Used: - Vilsa Stealer, hvnc.py
Threat Score: - High (8.5/10) — Due to its advanced encryption, persistence mechanisms, and broad targeting capabilities.
Last Threat Observation: - October 7, 2024 (Observed by multiple cybersecurity researchers)

Overview

Vilsa Stealer is a sophisticated information-stealing malware that has recently emerged, primarily designed to extract sensitive data from compromised systems. It targets a wide range of data, including browser credentials, cryptocurrency wallet information, and tokens from various applications. Its techniques involve anti-analysis methods, persistence, and encryption, making it a significant threat to both individuals and organizations. It is known for its use of Python programming and integrates multiple anti-VM detection methods and data exfiltration techniques via the GoFile API.

Key Details

  • Delivery Method: Typically distributed through phishing campaigns or bundled with other malicious software found on dark web forums.
  • Target: Web browser data, cryptocurrency wallets, Telegram data, and other sensitive application data.
  • Functions:
    • Virtual machine detection to evade sandbox environments.
    • Data exfiltration using GoFile API.
    • Deployment of hvnc.py malware for remote access.
    • Encryption of stolen data for secure transmission to threat actors.
  • Obfuscation: Uses Fernet symmetric encryption to mask its behavior and evade detection.

Attack Vectors

Vilsa Stealer deploys several methods to infiltrate and sustain its presence on infected systems:

  • Persistence: Copies itself into the Startup folder to ensure execution upon system boot.
  • Anti-VM Techniques: Detects virtual environments by checking for specific DLL files and alters its behavior to avoid detection.
  • Data Exfiltration: Uses the GoFile API to upload stolen data to remote servers, including browser credentials and Telegram data.
  • UAC Bypass: Attempts to manipulate User Account Control (UAC) to disable security features on the host machine.

Known Indicators of Compromise (IoCs)

  • File Hashes:
    • MD5: 2b4df2bc6507f4ba7c2700739da1415d
    • SHA1: 53e3684138bc2cf00aa15b26c4b1ee3ee778fdef
    • SHA256: f5c5845e5531ed7a9f39fd665fb712baa557799b4a6bd9e92c7ef76d43eb5064
  • Domains:
    • bundeskriminalamt.agency
  • IPv4 Address:
    • 83.136.208.208

Mitigation and Prevention

  • User Awareness: Training to recognize phishing attempts and avoid downloading suspicious files.
  • Email Filtering: Implement strict filtering rules to block potential phishing emails that could deliver Vilsa Stealer.
  • Antivirus Protection: Use updated antivirus software with heuristic scanning to detect encrypted threats.
  • Two-Factor Authentication (2FA): Enforce 2FA to add an extra layer of security to accounts.
  • Monitor Logs: Regularly review system and network logs for unusual activity indicative of malware behavior.
  • Regular Updates: Ensure all software, including browsers and plugins, is up to date to minimize vulnerabilities.

MITRE ATT&CK Techniques Used

  • T1129: Shared Modules
  • T1497.001: Virtualization/Sandbox Evasion
  • T1082: System Information Discovery
  • T1071: Application Layer Protocol
  • T1202: Indirect Command Execution
  • T1140: Deobfuscate/Decode Files or Information
  • T1036: Masquerading
  • T1070.006: Timestomp
  • T1560: Archive Collected Data
  • T1059: Command and Scripting Interpreter
  • T1083: File and Directory Discovery
  • T1057: Process Discovery
  • T1041: Exfiltration Over C2 Channel
  • T1486: Data Encrypted for Impact
  • T1573: Encrypted Channel
  • T1518.001: Security Software Discovery
  • T1574.002: DLL Side-Loading

Conclusion

Vilsa Stealer represents a growing threat in the landscape of data theft malware due to its advanced capabilities in persistence, obfuscation, and exfiltration. Organizations should prioritize detection and prevention measures against this malware by strengthening their cybersecurity posture, focusing on user education, and maintaining a robust incident response plan.

Sources:

  1. CYFIRMA - Detailed analysis on Vilsa Stealer's tactics and capabilities.
  2. NetmanageIT Blog - Technical breakdown of Vilsa Stealer's behavior and its targeting of browser and crypto-wallet data.
  3. AlienVault Open Threat Exchange (OCX) - Indicator details and additional technical specifications of Vilsa Stealer.