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Threat Model Analysis for spartnernl/laravel-excel

Threat: Malicious File Masquerading (XML Bomb, Zip Bomb, etc.)

  • Threat: Malicious File Masquerading (XML Bomb, Zip Bomb, etc.)

    • Description: An attacker uploads a file disguised as a valid spreadsheet (e.g., .xlsx, .csv). The file contains malicious payloads like an XML bomb (nested entities causing exponential expansion) or a Zip bomb (highly compressed file that expands to consume excessive resources). The attacker exploits vulnerabilities in the underlying parsing libraries (PhpSpreadsheet) used by Laravel-Excel.
    • Impact: Denial of Service (DoS) due to resource exhaustion (memory, CPU, disk space). Potential for Remote Code Execution (RCE) if a vulnerability in the parsing library (PhpSpreadsheet) is successfully exploited. Application crash.
    • Affected Component: Laravel-Excel's import functionality, specifically the ToModel, ToCollection, ToArray, WithHeadingRow, and any custom import classes that utilize PhpSpreadsheet's file loading and parsing methods. The underlying PhpSpreadsheet library is the primary target.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Strict File Type Validation: Implement robust file type validation beyond checking the file extension. Verify the file's magic bytes/header.
      • File Size Limits: Enforce strict file size limits on uploads.
      • Resource Limits: Configure PHP's memory_limit and max_execution_time.
      • Sandboxing: Run the spreadsheet parsing process in a sandboxed environment (e.g., Docker container).
      • Library Updates: Keep Laravel-Excel and PhpSpreadsheet updated.
      • Pre-emptive Parsing Checks: Consider using libraries or techniques to detect potential bombs before full parsing.

Threat: Formula Injection (CSV/XLSX)

  • Threat: Formula Injection (CSV/XLSX)

    • Description: An attacker injects malicious formulas into spreadsheet files. If user-supplied data is used without proper escaping when exporting spreadsheets, an attacker could craft input that results in malicious formulas being included in the generated file. When the file is opened, the formulas execute, potentially leading to data exfiltration or client-side code execution.
    • Impact: Data exfiltration. Client-side code execution (running arbitrary code on the user's machine when they open the spreadsheet). Compromise of the user's system.
    • Affected Component: Laravel-Excel's export functionality (FromCollection, FromQuery, FromArray, FromView, etc.) when user-provided data is included. Import functionality if formulas are not sanitized after import.
    • Risk Severity: High
    • Mitigation Strategies:
      • Strict Input Sanitization (for Exports): Always escape user-provided data before including it in exported spreadsheets. Use escaping functions provided by Laravel-Excel and PhpSpreadsheet specific to the target file format.
      • Formula Sanitization (for Imports): If preserving some formulas after import, use a dedicated formula parser/sanitizer.
      • Content Security Policy (CSP): If spreadsheet data is displayed in a web context, use a CSP.
      • User Education: Educate users about the risks of opening untrusted spreadsheets.

Threat: Unintended Data Exposure in Exports

  • Threat: Unintended Data Exposure in Exports

    • Description: The application's export functionality is not properly secured, allowing users to generate spreadsheets containing data they should not have access to. This is due to missing authorization checks or flaws in the data filtering logic within the export process itself.
    • Impact: Data breach. Exposure of sensitive information. Violation of privacy regulations.
    • Affected Component: Laravel-Excel's export functionality (FromCollection, FromQuery, FromArray, FromView, etc.).
    • Risk Severity: High
    • Mitigation Strategies:
      • Strict Access Control: Implement robust authorization checks before generating any export, specifically within the export logic. Ensure the user has permissions to view all data included.
      • Laravel Authorization: Use Laravel's Policies and Gates to control access to data during the export process.
      • Data Filtering: Carefully filter the data being exported based on user permissions and context within the export code.