{
  "family": "fullscreen",
  "sample_count": 8,
  "category": "ransomware",
  "description": "Adware:Win32/Fullscreen is an aggressive, highly disruptive Potentially Unwanted Program (PUA) and adware family designed to monetize an infected endpoint by forcefully injecting massive, full-screen advertisements into the user's web browser or directly onto the Windows desktop, regardless of what the user is doing.<br><br><b>Understanding Fullscreen Adware</b><br>To an end-user, a Fullscreen infection renders the computer nearly unusable. The adware completely hijacks the screen real estate, constantly interrupting workflows with unavoidable, full-screen pop-ups that are often difficult to close. For a security analyst, this represents a severe degradation of endpoint functionality and a significant risk of secondary infections, as these aggressive ads frequently employ malvertising to deploy actual trojans or ransomware.<br><br><b>Execution and Disruption Mechanics</b><br>Fullscreen is typically distributed via deceptive software bundlers (`T1189`) found on torrent sites or third-party freeware portals. Upon execution (`T1204.002`), it establishes deep persistence, often creating multiple randomized Scheduled Tasks (`T1053.005`) and Registry Run keys to ensure it survives reboots. It utilizes hidden browser extensions (`T1176`) or standalone adware processes to intercept web traffic and inject its payload. It deliberately uses Windows UI APIs (`T1562`) to force the advertisement windows to stay 'always on top' and maximize to full screen, maximizing the chance the user accidentally clicks the ad and generates affiliate revenue.<br><br><b>Indicators of Compromise & Impact</b><br>The primary impact is the total loss of user productivity and the high risk of secondary malvertising infections. Incident responders will observe anomalous HTTP/HTTPS traffic routing through known, aggressive adware affiliate networks. EDR logs will flag the installation of the rogue Scheduled Tasks and the constant launching of hidden browser instances or unknown executables attempting to draw full-screen UI elements.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Fullscreen and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Fullscreen 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 Fullscreen establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Fullscreen 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 Fullscreen compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Fullscreen 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 Fullscreen employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Fullscreen 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 Fullscreen, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Fullscreen 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": [
    "T1053.005",
    "T1189",
    "T1204.002",
    "T1176"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1189",
      "name": "Drive-by Compromise (Bundled Installers)",
      "tactic": "Initial Access"
    },
    {
      "id": "T1053.005",
      "name": "Scheduled Task/Job: Scheduled Task (Persistence for pop-ups)",
      "tactic": "Persistence"
    },
    {
      "id": "T1176",
      "name": "Browser Extensions",
      "tactic": "Persistence"
    },
    {
      "id": "T1204.002",
      "name": "User Execution: Malicious File",
      "tactic": "Execution"
    }
  ],
  "containment_steps": [
    "Use the Windows Control Panel to attempt uninstallation of the adware and any bundled software installed on the exact same date.",
    "Deploy an enterprise adware removal tool (e.g., AdwCleaner or Malwarebytes) to locate and strip the deeply embedded Scheduled Tasks and hidden registry hooks.",
    "Force a complete reset of all installed web browsers to factory defaults to eradicate rogue extensions.",
    "If the full-screen ads prevent interaction with the desktop, reboot the computer into Safe Mode to perform the cleanup."
  ],
  "what_to_avoid": [
    "Do not instruct the user to simply 'click the X' on the ads; aggressive adware often fakes the close button to register an illicit click or trigger a secondary download.",
    "Avoid ignoring the infection; the malvertising networks utilized by Fullscreen often rotate their payloads and may drop severe malware."
  ],
  "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"
  ]
}