{
  "family": "crowti",
  "sample_count": 3,
  "category": "ransomware",
  "description": "Ransom:Win32/Crowti is Microsoft's internal detection designation for the infamous **CryptoWall** ransomware family. Emerging in the mid-2010s as a successor to CryptoLocker, CryptoWall (Crowti) was one of the most widespread and financially devastating ransomware strains in history. It pioneered the use of the Tor anonymity network for Command and Control (C2) and heavily refined the Ransomware-as-a-Service (RaaS) affiliate distribution model.<br><br><b>Understanding Crowti (CryptoWall Ransomware)</b><br>To an end-user, the impact is catastrophic: all personal documents, photos, and databases are suddenly inaccessible, appended with random extensions, and the desktop background is replaced with a ransom note demanding Bitcoin payment via a Tor hidden service. For a security team, a Crowti infection represents a severe breach, as the ransomware's robust RSA-2048 encryption (`T1486`) is mathematically impossible to break without the private key held by the attackers.<br><br><b>Execution and Encryption Mechanics</b><br>Crowti was distributed via massive malspam campaigns containing weaponized CHM (Compiled HTML Help) files (`T1566.001`), JavaScript droppers, or via exploit kits (like Angler or Nuclear) (`T1189`). Upon execution (`T1204.002`), it establishes persistence in the Registry (`T1547.001`) and aggressively deletes Volume Shadow Copies (`vssadmin.exe Delete Shadows /All /Quiet`) (`T1490`) to prevent easy recovery. It communicates with its C2 server via heavily obfuscated proxies (like I2P or Tor) (`T1090.003`) to receive its unique public encryption key, and then systematically encrypts user files across local drives and mapped network shares (`T1486`).<br><br><b>Indicators of Compromise & Impact</b><br>The impact is total data loss and severe business disruption. Host-based IoCs include EDR alerts for the execution of `vssadmin.exe`, massive bursts of file modification operations, the dropping of ransom notes (e.g., `HELP_DECRYPT.HTML`, `HELP_YOUR_FILES.TXT`), and the presence of the Crowti executable hiding in `%AppData%`. Network IoCs include DNS requests to known Tor gateways or I2P proxies.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1486",
    "T1090.003",
    "T1547.001",
    "T1490"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1486",
      "name": "Data Encrypted for Impact",
      "tactic": "Impact"
    },
    {
      "id": "T1490",
      "name": "Inhibit System Recovery (Deleting Shadow Copies)",
      "tactic": "Impact"
    },
    {
      "id": "T1090.003",
      "name": "Proxy: Multi-hop Proxy (Use of Tor/I2P for C2)",
      "tactic": "Command and Control"
    },
    {
      "id": "T1547.001",
      "name": "Boot or Logon Autostart Execution",
      "tactic": "Persistence"
    }
  ],
  "containment_steps": [
    "IMMEDIATELY sever network connectivity to the infected endpoint to prevent Crowti from encrypting data on mapped corporate network shares.",
    "Do not attempt to reboot the machine if the encryption process is still actively running, as this may corrupt partially encrypted files.",
    "Identify the initial entry vector (e.g., the specific phishing email or malicious CHM file) and purge it from the corporate environment.",
    "Restore the affected systems from secure, offline backups that were not accessible to the infected endpoint."
  ],
  "what_to_avoid": [
    "Do not rely on Volume Shadow Copies for recovery, as Crowti's first action is to delete them.",
    "Avoid paying the ransom unless absolutely critical for business survival, as it funds further cybercrime and there is no guarantee of receiving the decryptor."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}