{
  "family": "zenfly",
  "sample_count": 1,
  "category": "ransomware",
  "description": "<h3>Executive Summary</h3>\nZenfly is a malicious Trojan designed to covertly infiltrate Windows systems, establish persistence, and act as a reliable downloader for remote threat actors. It is frequently utilized in the initial stages of a cyberattack to gather system intelligence and facilitate the automated deployment of secondary, highly destructive malware payloads, such as enterprise ransomware or banking trojans.\n\n<h3>Infection Vector and Technical Capabilities</h3>\nZenfly is predominantly distributed through socially engineered spam campaigns containing malicious attachments (often weaponized PDFs or Office documents utilizing macro exploits) or via compromised software installers downloaded from untrustworthy web portals.\n\nUpon successful execution, Zenfly operates with a focus on stealth and payload delivery:\n<ul>\n<li><strong>System Reconnaissance:</strong> The trojan immediately collects detailed system information, including the OS version, installed software, Active Directory domain membership, and active antivirus solutions. This fingerprint is transmitted to a command-and-control (C2) server.</li>\n<li><strong>Persistence:</strong> Zenfly ensures it survives system reboots by modifying the Windows Registry (e.g., adding entries to the `Run` or `RunOnce` keys) or by creating hidden Scheduled Tasks that execute the malware payload under high privileges.</li>\n<li><strong>Payload Delivery:</strong> Acting as a downloader, Zenfly receives instructions from the C2 server to silently download and execute secondary malware. This provides the attacker with a flexible platform to escalate the attack based on the value of the compromised host.</li>\n</ul>\n\n<h3>Threat Assessment</h3>\nA Zenfly infection represents a significant breach of the endpoint perimeter. Because it provides remote attackers with the ability to execute arbitrary code, a single compromised machine can rapidly be utilized to pivot laterally and compromise the entire corporate network.\n\n<h3>Remediation and Eradication</h3>\n<ul>\n<li><strong>Endpoint Detection and Response (EDR):</strong> Configure EDR solutions to monitor for anomalous registry modifications and unauthorized outbound network connections to unknown IP addresses.</li>\n<li><strong>Network Isolation and Sweeps:</strong> Immediately isolate the infected endpoint from the LAN. Conduct a thorough forensic sweep to identify not only the Zenfly executable but also any secondary payloads it may have successfully deployed.</li>\n<li><strong>Credential Reset:</strong> Because Zenfly frequently facilitates the deployment of info-stealers, all user credentials associated with the compromised endpoint must be treated as compromised and immediately reset.</li>\n</ul>",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [
    "Trojan.Zenfly",
    "Downloader.Zenfly",
    "Win32/Zenfly"
  ],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Zenfly and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Zenfly 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 Zenfly establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Zenfly 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 Zenfly compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Zenfly 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 Trojan.Zenfly employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Trojan.Zenfly 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 Trojan.Zenfly, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Trojan.Zenfly 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": [
    "T1105",
    "T1547.001",
    "T1059"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-10-15",
  "type": "Trojan",
  "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,
  "mitre_attack_detail": [
    {
      "id": "T1105",
      "name": "Ingress Tool Transfer",
      "tactic": "Command and Control"
    },
    {
      "id": "T1547.001",
      "name": "Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder",
      "tactic": "Persistence"
    },
    {
      "id": "T1059",
      "name": "Command and Scripting Interpreter",
      "tactic": "Execution"
    }
  ],
  "containment_steps": [
    "Immediately isolate affected host(s) from the internal network (disconnect physical Ethernet and disable Wi-Fi/Bluetooth) to prevent Zenfly from spreading laterally or encrypting network-attached storage (NAS) and shared SMB volumes.",
    "Preserve volatile system memory (RAM capture) on a representative endpoint before attempting a reboot or power-down, as Zenfly symmetric encryption keys or uncompiled payload components may still reside in memory.",
    "Audit process execution logs and terminate active scripting interpreters (e.g. PowerShell, CMD, WScript) or commands executing 'vssadmin.exe delete shadows' or 'wbadmin' used by Zenfly to inhibit recovery.",
    "Investigate the initial compromise vector (such as exposed RDP instances, spearphishing attachments, or vulnerable edge gateways) and enforce an immediate credential reset for all compromised Active Directory accounts.",
    "Restore critical assets and databases exclusively from verified, air-gapped, or immutable offline backups once the Zenfly binary and related persistence hooks are eradicated."
  ],
  "what_to_avoid": [
    "Do not restart or power cycle infected systems prematurely; doing so destroys volatile RAM encryption keys and may trigger bootloader locking logic embedded in Zenfly.",
    "Avoid negotiating or paying the extortion demand without prior forensic evaluation and consultation with incident response specialists, as payment does not guarantee data recovery.",
    "Do not connect clean backup drives or external storage to the affected network until Zenfly eradication is completely verified."
  ],
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows Server 2022",
    "Windows Server 2019"
  ]
}