{
  "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": [
    {
      "@type": "Question",
      "name": "What is Crowti and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Crowti is classified as a Ransomware. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments."
      }
    },
    {
      "@type": "Question",
      "name": "How does Crowti establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Crowti typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks."
      }
    },
    {
      "@type": "Question",
      "name": "What are the essential incident response steps for mitigating a Crowti compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Crowti should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups."
      }
    },
    {
      "@type": "Question",
      "name": "What cryptographic algorithms and file targeting techniques does Crowti employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Crowti typically leverages hybrid cryptographic architectures combining symmetric stream or block ciphers (such as AES-256 or ChaCha20) for rapid file encryption with asymmetric algorithms (such as RSA-2048 or Curve25519) to securely protect the session keys. It aggressively targets sensitive file extensions including corporate documents, databases, virtual disks, and backups while systematically executing commands to delete Volume Shadow Copies (vssadmin delete shadows /all /quiet) and disable system recovery options."
      }
    },
    {
      "@type": "Question",
      "name": "Are decryptors available for Crowti, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Crowti depends on whether security researchers or law enforcement (such as the No More Ransom initiative) have recovered the master private keys or discovered flaws in its key generation routines. Victims should never pay the extortion demand, as payment fuels criminal operations without guaranteeing file restoration. The recommended recovery procedure entails isolating infected hosts, conducting forensic disk imaging, identifying the root access vector, and restoring validated systems from immutable offline backups."
      }
    }
  ],
  "faq_count": 5,
  "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": [
    "Healthcare",
    "Critical Infrastructure",
    "Enterprise"
  ],
  "motivation": "Financial Extortion",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "defense_evasion",
    "impact"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows Server 2022",
    "Windows Server 2019"
  ]
}