{
  "family": "sytro",
  "sample_count": 273,
  "category": "trojan_generic",
  "description": "Worm:Win32/Sytro is a pervasive network worm and file infector notorious for rapidly propagating across local networks and removable media, causing severe system instability and network congestion.<br><br><b>What is Sytro?</b><br>For general users, a Sytro infection causes significant disruption, often hiding legitimate files on USB drives, dropping unwanted shortcuts, and severely slowing down the operating system. For incident responders, it represents a noisy, classic propagation threat. Sytro is highly aggressive in its lateral movement, seeking to infect every reachable machine on a subnet.<br><br><b>Infection Vectors & Threat Hunting</b><br>Sytro 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 manual 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 Sytro 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>, <code>.lnk</code>, or randomly named <code>.exe</code> files on the root of network shares and USB drives.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1547.001",
    "T1564.001",
    "T1091",
    "T1562.001",
    "T1105"
  ],
  "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"
  ]
}