{
  "family": "pjtbinder",
  "sample_count": 2,
  "category": "ransomware",
  "description": "HackTool:Win32/Pjtbinder is a heuristic detection for a specific family of 'File Binders' or 'Joiners'. These are specialized utilities utilized by malware authors to package a malicious payload (like a trojan, keylogger, or ransomware) alongside a legitimate, 'decoy' file (such as a PDF document, an image, or a game installer) into a single, cohesive executable wrapper. When the victim is tricked into opening this file, the decoy opens normally, providing a false sense of security while the malware silently executes in the background.<br><br><b>Understanding Pjtbinder (File Binders)</b><br>To an end-user, the execution appears completely normal; they click an invoice, and the invoice opens. For a security analyst, a file binder is a critical component of social engineering (`T1204.002`). It is designed to bypass human suspicion and often employs rudimentary obfuscation to bypass static antivirus signatures.<br><br><b>Execution and Deception Mechanics</b><br>Pjtbinder operates by creating a 'stub' executable (`T1027`). This stub contains both the compressed decoy file and the compressed malware payload. Upon execution by the victim, the stub extracts both files into a temporary directory (frequently `%Temp%` or `AppData`). It then uses the Windows API (like `ShellExecute`) to open the decoy file with its associated application (e.g., opening the PDF with Adobe Reader), while simultaneously launching the malicious payload (`T1055`) as a hidden, background process.<br><br><b>Indicators of Compromise & Impact</b><br>The impact is entirely dependent on the hidden payload. Host-based IoCs are highly behavioral. EDR will detect 'Suspicious Process Spawning'—for example, a seemingly innocuous document file (which is actually the compiled executable binder) spawning `cmd.exe`, `powershell.exe`, or dropping unknown binaries into the `%Temp%` directory immediately upon execution. Static analysis of the flagged file will reveal an executable with multiple embedded files or highly anomalous section headers.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1055",
    "T1027",
    "T1204.002"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1204.002",
      "name": "User Execution: Malicious File (The core mechanism of a binder)",
      "tactic": "Execution"
    },
    {
      "id": "T1027",
      "name": "Obfuscated Files or Information (Packaging and hiding the payload)",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1055",
      "name": "Process Injection (Often used by the stub to execute the payload silently)",
      "tactic": "Defense Evasion"
    }
  ],
  "containment_steps": [
    "Immediately quarantine the flagged file to prevent further execution or distribution.",
    "Analyze EDR telemetry (process trees) to determine exactly what the binder spawned and what payload was dropped upon execution.",
    "Submit the bound executable to a dynamic analysis sandbox (like Any.Run or Cuckoo) to safely detonate it and separate the decoy from the payload.",
    "Conduct proactive threat hunting across the enterprise for the hash of the extracted, hidden payload."
  ],
  "what_to_avoid": [
    "Do not assume a file is safe simply because it has a familiar icon (e.g., a PDF icon); binders routinely spoof icons to aid the deception.",
    "Avoid relying purely on static scanning; the binder wrapper often obfuscates the payload, requiring behavioral analysis to understand the threat."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}