{
  "family": "bagle",
  "sample_count": 8,
  "category": "backdoor",
  "description": "Bagle (classified in antivirus detection telemetry under designations including Backdoor:Win32/Bagle, Backdoor.Win32.Bagle, and Win32/Bagle) is a interactive remote access trojan and backdoor providing remote threat actors with unauthorized terminal control, file manipulation, and surveillance. Disseminated across enterprise networks and consumer workstations via social engineering, phishing attachments, malicious drive-by downloads, or weaponized software cracks, Bagle 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 reverse shell connections, process hollowing, privilege escalation, and lateral movement reconnaissance. 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": [
    "Backdoor:Win32/Bagle",
    "Backdoor.Win32.Bagle",
    "Win32/Bagle"
  ],
  "enrichment_level": "curated_sourced",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Backdoor:Win32/Bagle?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Bagle is a backdoor threat designed to infiltrate Windows systems and execute unauthorized operations without user consent."
      }
    },
    {
      "@type": "Question",
      "name": "How does Bagle 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 Bagle 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 Bagle 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 Bagle?",
      "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",
    "T1055",
    "T1573",
    "T1547.001",
    "T1070"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-10-16",
  "mitre_attack_detail": [
    {
      "id": "T1534",
      "name": "Internal Spearphishing (Mass-mailing propagation)",
      "tactic": "Lateral Movement"
    },
    {
      "id": "T1114",
      "name": "Email Collection (Harvesting addresses for spamming)",
      "tactic": "Collection"
    },
    {
      "id": "T1071",
      "name": "Application Layer Protocol (Listening backdoor on TCP 6777)",
      "tactic": "Command and Control"
    },
    {
      "id": "T1204.002",
      "name": "User Execution: Malicious File",
      "tactic": "Execution"
    }
  ],
  "containment_steps": [
    "Isolate the endpoint from the network immediately to halt the mass-mailing engine and sever the remote backdoor connection on port 6777.",
    "Block outbound SMTP (Port 25) traffic at the enterprise firewall for all workstations, ensuring only authorized mail servers can send email.",
    "Use an enterprise antivirus solution to scan the Windows System directory and remove the Bagle executable and its registry persistence keys.",
    "Given the backdoor functionality, assume the endpoint may have received secondary payloads and perform a full forensic scan."
  ],
  "what_to_avoid": [
    "Do not trust the 'From:' address of a Bagle-infected email; the person listed there is almost certainly innocent due to sender spoofing.",
    "Avoid assuming the threat is modern; Bagle relies on early 2000s social engineering tactics, so an infection indicates a severe lack of security awareness training."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "persistence",
    "command_and_control",
    "remote_access"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "sources": [
    {
      "name": "Microsoft Defender Threat Encyclopedia - Backdoor:Win32/Bagle",
      "url": "https://www.microsoft.com/en-us/wdsi/threats/malware-encyclopedia-description?Name=Backdoor:Win32/Bagle"
    },
    {
      "name": "Kaspersky Threat Intelligence - Backdoor.Win32.Bagle",
      "url": "https://threats.kaspersky.com/en/threat/"
    },
    {
      "name": "MITRE ATT&CK - Enterprise Techniques",
      "url": "https://attack.mitre.org/techniques/T1059.003/"
    }
  ],
  "target_platforms": [
    "Windows 10",
    "Windows 7",
    "Windows XP",
    "Windows Server"
  ]
}