{
  "family": "pyinstaller",
  "sample_count": 1,
  "category": "ransomware",
  "description": "<h3>Executive Summary</h3>\nPyInstaller is not malware. It is a highly popular, legitimate, open-source utility used by developers to bundle Python scripts and their dependencies into standalone executable files (e.g., `.exe` for Windows). This allows Python applications to run on machines that do not have the Python interpreter installed. However, because it obfuscates the underlying script and bundles necessary DLLs, it is incredibly popular among malware authors, leading to frequent heuristic detections by security software.\n\n<h3>Infection Vector and Technical Capabilities (Contextual)</h3>\nWhen an antivirus engine flags a file as \"PyInstaller\" (often accompanied by terms like `Suspicious`, `Heur`, or `Generic`), it is typically a behavioral or heuristic flag rather than a specific malware signature. Threat actors use PyInstaller for several reasons:\n<ul>\n<li><strong>Rapid Malware Development:</strong> Python allows for the rapid development of info-stealers, ransomware, and RATs. PyInstaller provides the easiest method to package these scripts for deployment on victim Windows machines.</li>\n<li><strong>Evasion through Obfuscation:</strong> PyInstaller inherently packages the Python bytecode and a bootloader into the executable. This process obfuscates the original source code, making static analysis by traditional antivirus significantly more difficult.</li>\n<li><strong>Large File Size:</strong> PyInstaller executables are inherently large (often >5MB) because they include the entire Python environment. This large file size can sometimes bypass older antivirus engines configured to skip scanning large files to preserve system performance.</li>\n</ul>\n\n<h3>Threat Assessment</h3>\nA detection naming \"PyInstaller\" requires careful triage. If the organization actively develops Python applications and uses PyInstaller internally, it may be a false positive. However, if found on a standard user's endpoint in a temporary directory (like `%APPDATA%`), it is highly likely to be a compiled Python-based info-stealer or trojan attempting to evade detection.\n\n<h3>Incident Response and Remediation</h3>\n<ul>\n<li><strong>Reverse Engineering (Extraction):</strong> Incident responders can use tools like `pyinstxtractor` to unpack the compiled executable. This extracts the bundled `.pyc` (Python compiled bytecode) files.</li>\n<li><strong>Decompilation and Analysis:</strong> The extracted `.pyc` files can then be decompiled back into readable Python source code using tools like `uncompyle6` or `decompyle3`. This allows analysts to determine the exact nature and intent of the malware (e.g., identifying C2 servers or targeted data).</li>\n<li><strong>Behavioral Monitoring (EDR):</strong> Because the static file is obfuscated, eradication relies on EDR solutions that monitor the *behavior* of the process once it executes (e.g., attempting to read browser credential stores, encrypting files, or making unauthorized network connections).</li>\n</ul>",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [
    "Suspicious.PyInstaller",
    "Trojan.Python",
    "Heur.PyInstaller"
  ],
  "enrichment_level": "insufficient_information",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1027",
    "T1059.006"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-07-02T06:59:32Z",
  "type": "Utility / Frequently Weaponized",
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}