{
  "family": "vbkryjetor",
  "sample_count": 551,
  "category": "packer",
  "description": "Worm:Win32/VBKryjetor is a pervasive, Visual Basic-compiled network worm and trojan dropper notorious for rapidly propagating across removable media and local networks.<br><br><b>What is VBKryjetor?</b><br>For general users, VBKryjetor causes significant disruption, often hiding legitimate files on USB drives and replacing them with malicious executables. For incident responders, it represents a noisy, classic propagation threat. Because it is compiled in Visual Basic 6 (VB6), it is often bloated and easily decompiled, but its sheer volume and aggressive lateral movement capabilities make it a persistent nuisance in environments with poor USB controls.<br><br><b>Infection Vectors & Threat Hunting</b><br>VBKryjetor primarily spreads by copying itself to all connected removable drives, creating an <code>autorun.inf</code> file to automatically execute when the drive is accessed. It also scans local subnets for open SMB shares, attempting to copy itself to vulnerable network locations. Once executed on a host, it copies itself to the <code>%SystemRoot%</code> or <code>%AppData%</code> directories. It establishes persistence via the Registry Run keys and frequently disables critical administrative tools like Task Manager, Registry Editor, and Command Prompt to hinder removal.<br><br><b>Forensic Analysis & Impact</b><br>The impact is widespread nuisance, localized network congestion, and potential data loss (via hidden files). EDR platforms frequently detect VBKryjetor based on its unauthorized modifications to <code>HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\Policies\\System</code>. Threat hunters should investigate the sudden appearance of <code>.vbs</code> or randomly named <code>.exe</code> files on the root of network shares and USB drives. The worm also acts as a dropper, frequently downloading secondary adware or spyware payloads.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1564.001",
    "T1091",
    "T1562.001",
    "T1105",
    "T1547.001"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1091",
      "name": "Replication Through Removable Media",
      "tactic": "Lateral Movement"
    },
    {
      "id": "T1564.001",
      "name": "Hide Artifacts: Hidden Files and Directories",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1562.001",
      "name": "Impair Defenses: Disable or Modify Tools",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1547.001",
      "name": "Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder",
      "tactic": "Persistence"
    },
    {
      "id": "T1105",
      "name": "Ingress Tool Transfer",
      "tactic": "Command and Control"
    }
  ],
  "containment_steps": [
    "Enforce strict Group Policy restrictions disabling the 'AutoRun' and 'AutoPlay' features across the entire domain.",
    "Confiscate and forensically wipe any USB drives or removable media that were connected to the infected endpoint.",
    "Utilize command-line tools to forcefully unhide the legitimate directories on infected network shares and delete the malicious executables.",
    "Deploy a script via Group Policy to re-enable Task Manager, Registry Editor, and Command Prompt on affected endpoints."
  ],
  "what_to_avoid": [
    "Do not insert a potentially infected USB drive into a clean analysis machine unless AutoRun is strictly disabled and the machine is sandboxed.",
    "Avoid assuming the threat is contained after deleting the USB payload; the worm almost certainly copied itself to local network shares."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}