{
  "family": "winloadsda",
  "sample_count": 14,
  "category": "trojan_downloader",
  "description": "WinloadSDA (classified across security vendors as TrojanDownloader:Win32/WinloadSDA and Trojan:Win32/WinloadSDA) is an evasive trojan downloader and stager that masquerades as genuine Windows boot and system loader files (such as winload.exe). Distributed through compromised software downloads and exploit kits, WinloadSDA executes stealth sandbox evasion checks before establishing persistence under HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\Run. It connects via encrypted HTTPS POST requests to remote command-and-control servers, transmitting endpoint hardware identifiers and downloading secondary malicious payloads, including banking trojans, infostealers, and commodity ransomware.",
  "cta": "Published by the SystemHelpdesk Threat Intelligence Team.",
  "aliases": [
    "TrojanDownloader:Win32/WinloadSDA",
    "Trojan:Win32/WinloadSDA",
    "Win32/WinloadSDA",
    "WinloadSDA Loader",
    "WinloadSDA Trojan"
  ],
  "enrichment_level": "curated_sourced",
  "faq": [
    {
      "@type": "Question",
      "name": "What is TrojanDownloader:Win32/WinloadSDA?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "WinloadSDA is a trojan downloader that disguises itself as Windows system files to download secondary malware."
      }
    },
    {
      "@type": "Question",
      "name": "How does WinloadSDA evade static antivirus detection?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It mimics legitimate Windows system filenames and uses encrypted payload delivery over HTTPS."
      }
    },
    {
      "@type": "Question",
      "name": "What persistence mechanisms does WinloadSDA use?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It writes disguised autostart values to HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\Run and registers background tasks."
      }
    },
    {
      "@type": "Question",
      "name": "What secondary malware is delivered by WinloadSDA?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It commonly delivers credential stealers, banking trojans, and ransomware payloads."
      }
    },
    {
      "@type": "Question",
      "name": "How do you completely remove WinloadSDA?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Terminate suspicious loader processes, remove unauthorized registry Run entries, and run an updated antimalware scan."
      }
    }
  ],
  "faq_count": 5,
  "mitre_attack": [
    "T1105",
    "T1036.005",
    "T1547.001",
    "T1053.005",
    "T1071.001",
    "T1082"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-10-15",
  "mitre_attack_detail": [
    {
      "id": "T1189",
      "name": "Drive-by Compromise",
      "tactic": "Initial Access"
    },
    {
      "id": "T1176",
      "name": "Browser Extensions",
      "tactic": "Persistence"
    },
    {
      "id": "T1112",
      "name": "Modify Registry",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1562.001",
      "name": "Impair Defenses: Disable or Modify Tools",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1105",
      "name": "Ingress Tool Transfer",
      "tactic": "Command and Control"
    }
  ],
  "containment_steps": [
    "Quarantine the endpoint to halt the active exfiltration of browsing telemetry and the downloading of further adware modules.",
    "Audit Windows Group Policies and the Registry to remove any forced extension installation policies created by the adware.",
    "Deploy an enterprise adware removal tool (e.g., AdwCleaner) to locate and strip the deeply embedded registry hooks and watchdog services.",
    "Force a complete reset of all installed web browsers to factory defaults to eradicate the rogue extensions and restore the homepage."
  ],
  "what_to_avoid": [
    "Do not rely solely on the browser's 'remove extension' button; Winloadsda frequently uses GPOs and watchdog services to immediately reinstall itself.",
    "Avoid ignoring the infection; adware tracking data is highly detailed and may expose corporate activities or access to internal portals."
  ],
  "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/WinloadSDA",
      "url": "https://www.microsoft.com/en-us/wdsi/threats/malware-encyclopedia-description?Name=TrojanDownloader:Win32/WinloadSDA"
    },
    {
      "name": "Trend Micro Threat Encyclopedia - Trojan.Win32.WinloadSDA",
      "url": "https://www.trendmicro.com/vinfo/us/threat-encyclopedia/malware/trojan.win32.winloadsda"
    },
    {
      "name": "MITRE ATT&CK - Masquerading: Match Legitimate Name or Location (T1036.005)",
      "url": "https://attack.mitre.org/techniques/T1036/005/"
    }
  ],
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows 7"
  ]
}