{
  "family": "bisonal",
  "sample_count": 2,
  "category": "trojan",
  "description": "Bisonal (classified in antivirus detection telemetry under designations including Trojan:Win32/Bisonal, Trojan.Win32.Bisonal, and Win32/Bisonal) is a multi-stage trojan engineered to disguise itself as legitimate software, execute unauthorized commands, and coordinate with external command-and-control infrastructure. Disseminated across enterprise networks and consumer workstations via social engineering, phishing attachments, malicious drive-by downloads, or weaponized software cracks, Bisonal 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 deceptive executable masquerading, registry run key autostart, system telemetry gathering, and remote C2 beaconing. 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": [
    "Trojan:Win32/Bisonal",
    "Trojan.Win32.Bisonal",
    "Win32/Bisonal"
  ],
  "enrichment_level": "curated_sourced",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Trojan:Win32/Bisonal?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Bisonal is a trojan threat designed to infiltrate Windows systems and execute unauthorized operations without user consent."
      }
    },
    {
      "@type": "Question",
      "name": "How does Bisonal 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 Bisonal 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 Bisonal 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 Bisonal?",
      "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": [
    "T1059.003",
    "T1027",
    "T1547.001",
    "T1071.001",
    "T1105"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-10-16",
  "mitre_attack_detail": [
    {
      "id": "T1566.001",
      "name": "Phishing: Spearphishing Attachment (Primary initial access vector)",
      "tactic": "Initial Access"
    },
    {
      "id": "T1059",
      "name": "Command and Scripting Interpreter (Providing the backdoor shell)",
      "tactic": "Execution"
    },
    {
      "id": "T1543.003",
      "name": "Create or Modify System Process: Windows Service (Establishing deep persistence)",
      "tactic": "Persistence"
    },
    {
      "id": "T1041",
      "name": "Exfiltration Over C2 Channel (Stealing classified data)",
      "tactic": "Exfiltration"
    }
  ],
  "containment_steps": [
    "Immediately isolate the compromised endpoint and assume the entire domain is compromised; engage a specialized Incident Response (IR) firm.",
    "Perform a comprehensive enterprise-wide hunt for similar malware, focusing on the specific C2 infrastructure identified on the initial host.",
    "Initiate a full credential reset for the entire organization, as the attackers likely deployed tools like Mimikatz after establishing the backdoor.",
    "Analyze email gateways and proxy logs to identify the original spear-phishing email and determine if other employees were targeted or compromised."
  ],
  "what_to_avoid": [
    "Do not attempt to remediate an APT infection by simply deleting the Bisonal executable; the actors almost certainly have secondary backdoors deployed.",
    "Avoid communicating about the incident on the compromised corporate network; assume the attackers are monitoring emails."
  ],
  "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 - Trojan:Win32/Bisonal",
      "url": "https://www.microsoft.com/en-us/wdsi/threats/malware-encyclopedia-description?Name=Trojan:Win32/Bisonal"
    },
    {
      "name": "Kaspersky Threat Intelligence - Trojan.Win32.Bisonal",
      "url": "https://threats.kaspersky.com/en/threat/"
    },
    {
      "name": "MITRE ATT&CK - Enterprise Techniques",
      "url": "https://attack.mitre.org/techniques/T1059.003/"
    }
  ],
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows 7"
  ]
}