{
  "family": "jackservn",
  "sample_count": 17,
  "category": "trojan_downloader",
  "description": "Jackservn (classified in antimalware definitions under Trojan:Win32/Jackservn, TrojanDownloader:Win32/Jackservn, and Backdoor:Win32/Jackservn) is a stealthy modular trojan downloader and stager engineered to establish a persistent bridgehead on Windows systems and retrieve follow-on malicious packages. Disseminated primarily through malicious email attachments, deceptive software installers, and drive-by download vectors, Jackservn executes initial environment reconnaissance upon initial execution. It interrogates the operating system version, processor architecture, active defensive processes, and checks for virtualized hypervisors or debugger hooks to evade sandbox analysis. Once evasion checks succeed, Jackservn drops an executable binary into `%APPDATA%` or `%LOCALAPPDATA%` and creates a persistent Windows service or Scheduled Task for survivability across reboots. The trojan subsequently initiates HTTPS POST beacons to remote command-and-control servers, transmitting endpoint telemetry and receiving encrypted instructions to download, unpack, and launch secondary payloads, including banking trojans, info-stealers, and cryptominers.",
  "cta": "Published by the SystemHelpdesk Threat Intelligence Team.",
  "aliases": [
    "Trojan:Win32/Jackservn",
    "TrojanDownloader:Win32/Jackservn",
    "Win32/Jackservn",
    "Jackservn Loader",
    "Trojan.Jackservn"
  ],
  "enrichment_level": "curated_sourced",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Trojan:Win32/Jackservn?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Jackservn is a trojan downloader that infiltrates Windows systems, verifies evasion checks, and downloads secondary malware payloads."
      }
    },
    {
      "@type": "Question",
      "name": "How does Jackservn evade automated sandbox detection?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It checks for virtual machine artifacts, hypervisor registry keys, debugger processes, and sleep acceleration techniques before running."
      }
    },
    {
      "@type": "Question",
      "name": "What persistence mechanisms does Jackservn employ?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It creates disguised Windows background services and registers scheduled tasks disguised under benign system administrative names."
      }
    },
    {
      "@type": "Question",
      "name": "What types of secondary payloads does Jackservn deliver?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It typically downloads banking trojans, cryptocurrency miners, infostealers, and commodity ransomware onto target hosts."
      }
    },
    {
      "@type": "Question",
      "name": "How can network administrators detect Jackservn communications?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Inspect egress web traffic for anomalous HTTPS POST requests containing base64 or XOR encrypted system telemetry to unrated domains."
      }
    }
  ],
  "faq_count": 5,
  "mitre_attack": [
    "T1105",
    "T1059.003",
    "T1543.003",
    "T1053.005",
    "T1497.001",
    "T1071.001",
    "T1082"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-10-15",
  "mitre_attack_detail": [
    {
      "id": "T1105",
      "name": "Ingress Tool Transfer",
      "tactic": "Command and Control"
    },
    {
      "id": "T1055",
      "name": "Process Injection",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1547.001",
      "name": "Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder",
      "tactic": "Persistence"
    },
    {
      "id": "T1566.001",
      "name": "Phishing: Spearphishing Attachment",
      "tactic": "Initial Access"
    },
    {
      "id": "T1027",
      "name": "Obfuscated Files or Information",
      "tactic": "Defense Evasion"
    }
  ],
  "containment_steps": [
    "Isolate the endpoint immediately to prevent Jackservn from downloading and executing its secondary payloads (e.g., ransomware).",
    "Audit the Windows Task Scheduler and Registry Run keys to identify and remove the Jackservn persistence mechanisms.",
    "Review firewall and proxy logs to identify the C2 domains Jackservn attempted to contact, and block them enterprise-wide.",
    "Capture a live memory image (RAM dump) to extract the injected Jackservn modules and identify the secondary payloads."
  ],
  "what_to_avoid": [
    "Do not close an incident simply because the initial Jackservn dropper was quarantined; always verify if secondary payloads were downloaded.",
    "Avoid relying solely on manual file deletion, as the injected processes will likely just recreate the dropped binaries."
  ],
  "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,
  "sources": [
    {
      "name": "Microsoft Defender Security Intelligence - Trojan:Win32/Jackservn",
      "url": "https://www.microsoft.com/en-us/wdsi/threats/malware-encyclopedia-description?Name=Trojan:Win32/Jackservn"
    },
    {
      "name": "Sophos Threat Center - Trojan.Jackservn Analysis",
      "url": "https://www.sophos.com/en-us/threat-center/threat-analyses/viruses-and-spyware/Trojan-Jackservn"
    },
    {
      "name": "MITRE ATT&CK - Ingress Tool Transfer (T1105)",
      "url": "https://attack.mitre.org/techniques/T1105/"
    }
  ],
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows 7"
  ]
}