{
  "family": "screen",
  "sample_count": 1,
  "category": "ransomware",
  "description": "<h3>Executive Summary</h3>\n\"Screen\" (often categorized as ScreenLocker or Winlock) refers to a specific subclass of Ransomware that primarily aims to extort victims by denying access to the operating system's graphical user interface (GUI), rather than encrypting the underlying files. While technically less sophisticated than crypto-ransomware, ScreenLockers are highly disruptive and rely on intense psychological pressure to coerce payment.\n\n<h3>Infection Vector and Lock Mechanisms</h3>\nScreenLockers are frequently distributed via malvertising, drive-by downloads on compromised websites, or masquerading as legitimate software updates (like fake Adobe Flash Player installers).\n\nUpon execution, the malware immediately seizes control of the user's display:\n<ul>\n<li><strong>Interface Hijacking:</strong> The malware forces a full-screen application to the foreground, completely obscuring the Windows desktop. It actively disables keyboard shortcuts (like Alt+Tab, Ctrl+Alt+Del, and the Windows Key) to prevent the user from closing the lock screen or accessing the Task Manager.</li>\n<li><strong>Psychological Coercion:</strong> The lock screen typically displays a highly intimidating message. A common tactic involves masquerading as a local law enforcement agency (e.g., the FBI or local police), accusing the victim of downloading illegal content, and demanding a \"fine\" to be paid via untraceable methods like prepaid gift cards or cryptocurrency.</li>\n<li><strong>Persistence:</strong> The malware modifies registry keys (such as `Winlogon\\Shell`) to ensure the lock screen launches immediately upon system reboot, before the legitimate `explorer.exe` process can start.</li>\n</ul>\n\n<h3>Threat Assessment</h3>\nWhile highly disruptive to the individual user, ScreenLockers generally do not encrypt the underlying file system. Therefore, the data remains intact, provided the machine is not hastily formatted. However, the presence of a ScreenLocker indicates a failure in perimeter and endpoint security.\n\n<h3>Remediation and Eradication</h3>\n<ul>\n<li><strong>Safe Mode Boot:</strong> The primary remediation tactic is to reboot the infected machine into \"Safe Mode with Command Prompt.\" This bypasses the malware's registry persistence hooks, allowing an administrator to manually delete the malicious executable and repair the `Winlogon` registry keys.</li>\n<li><strong>Offline Scanning:</strong> If Safe Mode is also locked, the machine must be booted from a clean, offline Antivirus Rescue USB drive to scan and remove the infection without loading the compromised host operating system.</li>\n<li><strong>Do Not Pay:</strong> Payment should never be made. It funds criminal enterprise, and there is no guarantee the attackers will provide the unlock code.</li>\n</ul>",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [
    "Trojan-Ransom.Win32.Screen",
    "ScreenLocker",
    "Winlock"
  ],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Screen and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Screen 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 Screen establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Screen 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 Screen compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Screen 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-Ransom.Win32.Screen employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Trojan-Ransom.Win32.Screen 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-Ransom.Win32.Screen, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Trojan-Ransom.Win32.Screen 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",
    "T1112",
    "T1489"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-10-15",
  "type": "Ransomware",
  "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": "T1486",
      "name": "Data Encrypted for Impact",
      "tactic": "Impact"
    },
    {
      "id": "T1112",
      "name": "Modify Registry",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1489",
      "name": "Service Stop (Forcefully stopping AV services)",
      "tactic": "Impact"
    }
  ],
  "containment_steps": [
    "Immediately isolate affected host(s) from the internal network (disconnect physical Ethernet and disable Wi-Fi/Bluetooth) to prevent Screen 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 Screen 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 Screen 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 Screen 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 Screen.",
    "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 Screen eradication is completely verified."
  ],
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows Server 2022",
    "Windows Server 2019"
  ]
}