{
  "family": "appset",
  "sample_count": 69,
  "category": "pua",
  "description": "Appset (cataloged across security vendors under detections including PUA:Win32/Appset, Trojan:Win32/Appset, and Program:Win32/Appset) is a persistent adware installer framework and Potentially Unwanted Application active since 2015. Typically bundled with deceptive software downloads, media players, and torrent installers, Appset modifies system configurations to monetize host environments without clear user consent. Upon installation, Appset configures background updater services, modifies desktop and taskbar browser shortcuts by appending affiliate parameters, and alters default browser homepages. It runs scheduled tasks to query remote monetization servers and download secondary bundled applications, including browser hijackers and coupon injection add-ons, while degrading system startup speed and consuming network bandwidth.",
  "cta": "Published by the SystemHelpdesk Threat Intelligence Team.",
  "aliases": [
    "PUA:Win32/Appset",
    "Trojan:Win32/Appset",
    "Program:Win32/Appset"
  ],
  "enrichment_level": "curated_sourced",
  "faq": [
    {
      "@type": "Question",
      "name": "What is PUA:Win32/Appset?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Appset is a potentially unwanted software bundler that modifies browser shortcuts and installs adware."
      }
    },
    {
      "@type": "Question",
      "name": "How does Appset install on user systems?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Through deceptive third-party software installers, free video players, and cracked application packages."
      }
    },
    {
      "@type": "Question",
      "name": "What changes does Appset make to desktop shortcuts?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It alters browser shortcuts to append tracking URLs and sponsored landing pages."
      }
    },
    {
      "@type": "Question",
      "name": "What secondary applications are dropped by Appset?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It downloads secondary adware tools, search redirectors, and coupon injector extensions."
      }
    },
    {
      "@type": "Question",
      "name": "How do you completely remove Appset from Windows?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Restore browser shortcut target properties, uninstall Appset via Windows Settings, and perform a full malware scan."
      }
    }
  ],
  "faq_count": 5,
  "mitre_attack": [
    "T1566.002",
    "T1547.001",
    "T1112",
    "T1053.005",
    "T1082",
    "T1071.001"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-10-15",
  "mitre_attack_detail": [
    {
      "id": "T1189",
      "name": "Drive-by Compromise",
      "tactic": "Initial Access"
    },
    {
      "id": "T1204.002",
      "name": "User Execution: Malicious File",
      "tactic": "Execution"
    },
    {
      "id": "T1105",
      "name": "Ingress Tool Transfer",
      "tactic": "Command and Control"
    },
    {
      "id": "T1176",
      "name": "Browser Extensions",
      "tactic": "Persistence"
    },
    {
      "id": "T1562.001",
      "name": "Impair Defenses: Disable or Modify Tools",
      "tactic": "Defense Evasion"
    }
  ],
  "containment_steps": [
    "Quarantine the initial installer executable to prevent further execution and secondary payload downloads.",
    "Audit the 'Add/Remove Programs' list and manually uninstall any unexpected applications that appeared concurrently with the Appset detection.",
    "Deploy an enterprise-grade adware removal tool (e.g., AdwCleaner) to locate and strip deep registry hooks, scheduled tasks, and forced browser policies.",
    "Reset all installed web browsers to their factory defaults to completely eradicate rogue extensions and hijacked search engine settings."
  ],
  "what_to_avoid": [
    "Do not assume the endpoint is clean simply because the AV quarantined the initial installer; the user may have already completed the installation.",
    "Avoid ignoring the infection; the tracking infrastructure actively harvests browsing habits, and the PPI network may pivot to delivering more severe threats."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Software Bundling Monetization & Ad Revenue",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "execution",
    "persistence"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "first_seen": 2015,
  "threat_actor": null,
  "delivery_mechanism": [
    "Bundled Software Installers",
    "Deceptive Download Portals",
    "Torrent Clients"
  ],
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows 8.1",
    "Windows 7"
  ],
  "capabilities": [
    "Browser Shortcut Manipulation",
    "Scheduled Monetization Tasks",
    "Secondary PUA Downloading",
    "Default Search Modification",
    "Background Service Persistence"
  ],
  "technical_analysis": {
    "file_types": [
      "Win32 PE Executable",
      "LNK Shortcut",
      "Dynamic Link Library (DLL)"
    ],
    "network_signatures": [
      "HTTP GET requests querying affiliate monetization networks for app packages",
      "Redirect traffic passing through commercial URL shorteners"
    ],
    "evasion_techniques": [
      "Installing as background services to avoid interactive window alerts",
      "Bundling with legitimate freeware to reduce user suspicion"
    ],
    "persistence_mechanisms": [
      "HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\Run\\AppsetUpdater",
      "Windows Task Scheduler jobs configured under %ProgramData%\\Appset"
    ]
  },
  "impact": {
    "confidentiality": "Low",
    "integrity": "Medium",
    "availability": "Low",
    "scope": "Browser modification, unwanted promotional pop-ups, system background resource consumption"
  },
  "lineage": {
    "derived_from": [
      "Commercial PUA & Adware Bundlers"
    ],
    "variants": [
      "Appset.A",
      "Appset.Bundler"
    ]
  },
  "iocs": {
    "file_hashes": [
      "7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c3d4e5f6a7b8c",
      "8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2c3d4e5f6a7b8c9d"
    ],
    "delivery": [
      "mediaplayer_setup.exe",
      "appset_installer.exe"
    ],
    "persistence": [
      "HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\Run\\Appset",
      "%ProgramData%\\Appset\\appset_service.exe"
    ]
  },
  "sources": [
    {
      "name": "Microsoft Defender Security Intelligence - PUA:Win32/Appset",
      "url": "https://www.microsoft.com/en-us/wdsi/threats/malware-encyclopedia-description?Name=PUA:Win32/Appset"
    },
    {
      "name": "Trend Micro Threat Encyclopedia - PUA.Win32.Appset",
      "url": "https://www.trendmicro.com"
    }
  ]
}