{
  "family": "jakyllhyde",
  "sample_count": 1,
  "category": "ransomware",
  "description": "<h3>Executive Summary</h3>\nJakyllHyde (a portmanteau of Jekyll and Hyde) is a highly evasive, two-faced malware family known for its polymorphic characteristics and split-personality execution flow. It is designed to present a completely benign facade during security analysis while delivering a destructive payload when deployed in a production environment.\n\n<h3>Evasion Tactics and Execution Flow</h3>\nJakyllHyde represents a masterclass in anti-analysis and sandbox evasion. The malware derives its name from its operational methodology:\n<ul>\n<li><strong>The \"Jekyll\" Phase (Evasion):</strong> Upon initial execution, the malware conducts exhaustive environmental checks. It looks for indicators of a virtual machine (VMware, VirtualBox drivers), debugging tools, or specific user activity (e.g., checking if the mouse has moved recently or if there are enough files in the \"Recent\" documents folder). If it suspects it is in a sandbox, it behaves like a harmless, benign application—often doing nothing more than writing a harmless text file or simply terminating cleanly.</li>\n<li><strong>The \"Hyde\" Phase (Execution):</strong> If the environmental checks pass (indicating a real, vulnerable user endpoint), the malware dynamically unpacks its true payload. This payload varies by campaign but is frequently a potent info-stealer or a downloader for ransomware.</li>\n</ul>\nThis split behavior allows JakyllHyde to bypass automated email gateways and static signature-based detection systems with ease.\n\n<h3>Security Implications</h3>\nJakyllHyde is incredibly dangerous because it provides a false sense of security. Security analysts or automated systems may analyze the file, observe the benign \"Jekyll\" behavior, and incorrectly classify the file as safe, allowing it to penetrate the network perimeter.\n\n<h3>Defense and Mitigation</h3>\n<ul>\n<li><strong>Advanced Behavioral Sandboxing:</strong> Utilize \"bare-metal\" sandboxing or next-generation sandboxes designed specifically to mimic real human interaction and obscure virtualization markers to trick the malware into its \"Hyde\" phase.</li>\n<li><strong>Continuous Endpoint Monitoring (EDR):</strong> Because initial static analysis may fail, robust EDR is essential to monitor the ongoing behavior of the process post-execution. EDR can detect the delayed unpacking or sudden malicious API calls that occur when the \"Hyde\" payload finally activates.</li>\n<li><strong>Threat Intelligence Sharing:</strong> Rapidly share Indicators of Compromise (IOCs) related to the unpacked \"Hyde\" payload across the security community, as the initial dropper hash will likely change rapidly due to polymorphism.</li>\n</ul>",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [
    "Trojan.JakyllHyde",
    "Evasive.JakyllHyde",
    "Win32/JakyllHyde"
  ],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Jakyllhyde and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Jakyllhyde 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 Jakyllhyde establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Jakyllhyde 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 Jakyllhyde compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Jakyllhyde 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.JakyllHyde employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Trojan.JakyllHyde 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.JakyllHyde, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Trojan.JakyllHyde 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": [
    "T1497.001",
    "T1497.002",
    "T1027"
  ],
  "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": "T1497.001",
      "name": "Virtualization/Sandbox Evasion: System Checks",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1497.002",
      "name": "User Activity Checks",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1027",
      "name": "Obfuscated Files or Information",
      "tactic": "Defense Evasion"
    }
  ],
  "containment_steps": [
    "Immediately isolate affected host(s) from the internal network (disconnect physical Ethernet and disable Wi-Fi/Bluetooth) to prevent Jakyllhyde 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 Jakyllhyde 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 Jakyllhyde 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 Jakyllhyde 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 Jakyllhyde.",
    "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 Jakyllhyde eradication is completely verified."
  ],
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows Server 2022",
    "Windows Server 2019"
  ]
}