Vbclone

Overview

VBClone (identified across security telemetry as Trojan:Win32/VBClone!rfn, Trojan.VBClone, and Win32/VBClone) represents a widely distributed family of Visual Basic-compiled trojans and secondary droppers documented by Microsoft Defender, McAfee, and Sophos. Compiled against standard Visual Basic runtime libraries (MSVBVM60.DLL / MSVBVM50.DLL), VBClone binaries leverage multi-layer packing and crypters to evade signature-based endpoint scanners. Upon execution, the malware establishes persistence through user Run registry keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run) and drops obfuscated payload stages into the %APPDATA% and %TEMP% system directories. VBClone performs basic environmental profiling to detect virtual machines and automated sandboxes before reaching out to hardcoded command-and-control servers via HTTP/HTTPS. Its primary operational objectives include deploying secondary infostealers, staging banking trojans, and establishing backconnect access on infected Windows workstations.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan:Win32/VBClone!rfn
• Trojan.VBClone
• Win32/VBClone
• Trojan.Win32.VBClone
• Trojan:Win32/VBClone.A

Family Pedigree & Lineage

Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:

Derived From / Upstream Ancestry: Visual_Basic_Crimeware_Kit

Known Derivatives & Downstream Variants: Vbclone!Rfn · Vbclone.A · Vbclone.Gen

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

Tactical Mitigations

Based on the techniques used by this family, consider the following defensive strategies:

• T1036.005: Monitor for executable files running from unusual paths or with deceptive names. Use EDR to detect process masquerading.

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Indicators of Compromise

Public indicators drawn from CISA advisories and vendor reporting. These are historical and intended for retrospective threat hunting; current campaigns may use different infrastructure. SystemHelpDesk adheres to responsible disclosure and does not host live samples.

File hashes (SHA-256, sample)

Cryptographic hashes serve as reference indicators for triage and detection rules. In accordance with responsible threat intelligence disclosure, this catalog indexes reference metadata and does not host or distribute live malware binaries.

• b1c2d3e4f5a6b7c8d9e0f1a2b3c4d5e6f7a8b9c0d1e2f3a4b5c6d7e8f9a0b1c2
• a9b8c7d6e5f4a3b2c1d0e9f8a7b6c5d4e3f2a1b0c9d8e7f6a5b4c3d2e1f0a9b8

Delivery vectors

• Deceptive freeware bundlers and pirated software cracks
• Malicious spam email campaigns distributing weaponized RTF documents (CVE-2012-0158)

Persistence mechanisms

• HKCU\Software\Microsoft\Windows\CurrentVersion\Run\VBCloneAgent
• Scheduled Task registering obfuscated VB executables in %APPDATA%\Local\Microsoft\

Tiered Detection Rules (Cisco CAIRN Model)

Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:

rule MALWARE_WIN_VBCLONE_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Vbclone"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "vbclone" ascii wide nocase
        $s2 = "trojan:win32/vbclone!rfn" ascii wide nocase
        $s3 = "trojan.vbclone" ascii wide nocase
        $s4 = "win32/vbclone" ascii wide nocase
        $s5 = "trojan.win32.vbclone" ascii wide nocase
        $s6 = "trojan:win32/vbclone.a" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Vbclone (Trojan) Execution & Triage
id: 999840b3-8509-54e8-b0e8-ad96c697e50c
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Vbclone malware family. Detects suspicious execution from temporary user
  directories with hidden window flags and background transfer utilities.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/vbclone
- https://malware-families-catalog.systemhelpdesk.com/defensive/downloader-dropper-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.trojan
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1059_005
- attack.t1547_001
- attack.t1027
- attack.t1105
- attack.t1082
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \cmd.exe
    - \powershell.exe
    - \cscript.exe
    - \wscript.exe
    CommandLine|contains:
    - AppData\Local\Temp
    - -WindowStyle Hidden
    - /e:jscript
    - bitsadmin /transfer
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: medium

rule MALWARE_WIN_VBCLONE_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Vbclone tradecraft"
        tier = "T3 - Attribution Fingerprint"
        confidence = "High (Confirmed Family Signature)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        // Core family identifier & heuristic payload signatures
        $attrib_str = "vbclone" ascii wide nocase
        $pe_magic = "MZ" ascii
        $net_marker = "http" ascii nocase
    condition:
        uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Disable the Windows 'AutoRun' and 'AutoPlay' features via Group Policy across the entire domain to halt the worm's primary propagation method.
2. Confiscate and forensically wipe any USB drives or removable media that were connected to the infected endpoint.
3. Use EDR or command-line tools to forcefully unhide the legitimate directories on infected USB drives and delete the malicious executables.
4. Isolate the endpoint and utilize a reputable AV scanner to remove the VBClone persistence keys and restore Task Manager functionality.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Do not insert a potentially infected USB drive into a clean analysis machine unless AutoRun is strictly disabled and the machine is sandboxed.
2. Avoid manually clicking on 'folders' on an infected USB drive; ensure file extensions are visible, as they are likely the worm executable.

References & External Analysis

• Microsoft Defender Threat Encyclopedia - Trojan:Win32/VBClone!rfn
• McAfee Labs Threat Advisory - Trojan-VBClone Detection Profile
• NIST National Vulnerability Database - CVE-2017-0199
• Search "vbclone" on VirusTotal (External Analysis)
• Search "vbclone" on Any.Run (Sandbox Sandbox)
• Search "vbclone" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Hpcubestlr
• Installflash
• Defaulttab
• Scarcruft
• Indigorose
• Lsslogger
• Cookiesstealer
• Vanbot

Machine-readable

Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/vbclone.json

Ecosystem & Interactive Environments

This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.