{
  "family": "bundleloader",
  "sample_count": 2,
  "category": "trojan_downloader",
  "description": "Bundleloader (classified in antivirus detection telemetry under designations including TrojanDownloader:Win32/Bundleloader, TrojanDownloader.Win32.Bundleloader, and Win32/Bundleloader) is a stealthy staging trojan engineered to establish host persistence and download secondary crimeware payloads onto compromised endpoints. Disseminated across enterprise networks and consumer workstations via social engineering, phishing attachments, malicious drive-by downloads, or weaponized software cracks, Bundleloader executes an initial reconnaissance phase upon system ingress. The binary evaluates host privileges, detects active hypervisors and sandbox environments to evade behavioral analysis, and establishes resilient autostart persistence by configuring registry keys under HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\Run or registering background Windows services. Operational mechanics characteristic of this family include sandbox evasion, staging directory payload extraction, autostart registry configuration, and encrypted HTTP/HTTPS payload delivery. Outbound communication is established with remote threat actor infrastructure to beacon operational status and receive tasking, posing significant security risks to data integrity and host availability.",
  "cta": "Published by the SystemHelpdesk Threat Intelligence Team.",
  "aliases": [
    "TrojanDownloader:Win32/Bundleloader",
    "TrojanDownloader.Win32.Bundleloader",
    "Win32/Bundleloader"
  ],
  "enrichment_level": "curated_sourced",
  "faq": [
    {
      "@type": "Question",
      "name": "What is TrojanDownloader:Win32/Bundleloader?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Bundleloader is a trojan downloader threat designed to infiltrate Windows systems and execute unauthorized operations without user consent."
      }
    },
    {
      "@type": "Question",
      "name": "How does Bundleloader compromise target systems?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It commonly infiltrates systems via phishing emails, trojanized software installers, exploit kits, or unpatched vulnerabilities."
      }
    },
    {
      "@type": "Question",
      "name": "What persistence mechanisms does Bundleloader utilize?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It typically creates autostart entries in the Windows Registry (HKCU/HKLM Run keys), registers scheduled tasks, or installs hidden background services."
      }
    },
    {
      "@type": "Question",
      "name": "What risks does Bundleloader pose to an enterprise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It can lead to credential theft, system manipulation, unauthorized remote access, data loss, or secondary malware delivery."
      }
    },
    {
      "@type": "Question",
      "name": "How can administrators detect and eliminate Bundleloader?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Deploy modern EDR solutions with updated behavioral signatures, isolate infected endpoints, audit autostart persistence entries, and conduct full antimalware scans."
      }
    }
  ],
  "faq_count": 5,
  "mitre_attack": [
    "T1105",
    "T1059.001",
    "T1547.001",
    "T1071.001",
    "T1082"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-10-16",
  "mitre_attack_detail": [
    {
      "id": "T1189",
      "name": "Drive-by Compromise (Distribution via third-party software portals)",
      "tactic": "Initial Access"
    },
    {
      "id": "T1566.002",
      "name": "Phishing: Spearphishing Link (Social engineering via deceptive installer UI)",
      "tactic": "Initial Access"
    },
    {
      "id": "T1105",
      "name": "Ingress Tool Transfer (Downloading the bundled adware/PUPs)",
      "tactic": "Command and Control"
    }
  ],
  "containment_steps": [
    "Use the Windows 'Programs and Features' Control Panel to meticulously review and uninstall all software installed on the date of the incident.",
    "Run a deep scan with a reputable enterprise Adware/PUP removal tool, as these bundles often leave persistent registry hooks.",
    "Reset all web browsers to default settings, as Bundleloaders frequently drop browser hijackers.",
    "Implement Application Control (e.g., AppLocker) to block execution from the `%Temp%` and `%Downloads%` directories for standard users."
  ],
  "what_to_avoid": [
    "Do not allow users to download software from unverified third-party aggregation sites (e.g., CNET Download, Softonic).",
    "Avoid quickly clicking 'Next' through freeware installers; always select the 'Custom' or 'Advanced' installation option to uncheck bundles."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "execution",
    "persistence"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "sources": [
    {
      "name": "Microsoft Defender Threat Encyclopedia - TrojanDownloader:Win32/Bundleloader",
      "url": "https://www.microsoft.com/en-us/wdsi/threats/malware-encyclopedia-description?Name=TrojanDownloader:Win32/Bundleloader"
    },
    {
      "name": "Kaspersky Threat Intelligence - TrojanDownloader.Win32.Bundleloader",
      "url": "https://threats.kaspersky.com/en/threat/"
    },
    {
      "name": "MITRE ATT&CK - Enterprise Techniques",
      "url": "https://attack.mitre.org/techniques/T1105/"
    }
  ],
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows 7"
  ]
}