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sec-design.md

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BUSINESS POSTURE

  • Business Priorities and Goals:
  • Enable PHP developers to create, read, and manipulate spreadsheet files (e.g., XLSX, CSV, ODS) programmatically.
  • Provide a robust and feature-rich library for handling complex spreadsheet operations.
  • Facilitate data exchange between PHP applications and spreadsheet software like Microsoft Excel, Google Sheets, and LibreOffice Calc.
  • Support various business processes that rely on spreadsheet data, such as reporting, data analysis, data import/export, and document generation.
  • Business Risks:
  • Data corruption or loss due to errors in spreadsheet processing or file handling.
  • Security vulnerabilities in the library could be exploited to compromise applications using phpspreadsheet, leading to data breaches or unauthorized access.
  • Incompatibility issues with different spreadsheet file formats or versions could disrupt business workflows.
  • Performance bottlenecks in spreadsheet processing could impact application responsiveness and user experience.
  • Legal and compliance risks if the library mishandles sensitive data or fails to meet data privacy regulations.

SECURITY POSTURE

  • Existing Security Controls:
  • security control: Code reviews by maintainers and contributors (described in project contribution guidelines).
  • security control: Static analysis tools integrated into development workflows (potentially visible in CI configurations).
  • security control: Unit and integration testing to ensure code correctness and prevent regressions (evident in test suite).
  • security control: Dependency management using Composer to manage third-party libraries and potentially address known vulnerabilities in dependencies (described in composer.json and composer.lock).
  • security control: Release process involving tagging and versioning to manage updates and security patches (visible in GitHub releases).
  • Accepted Risks:
  • accepted risk: Potential for undiscovered vulnerabilities in the library code due to complexity and community-driven development.
  • accepted risk: Reliance on community contributions for security fixes and timely patching of vulnerabilities.
  • accepted risk: Risk of vulnerabilities in third-party dependencies that are not immediately identified or patched.
  • Recommended Security Controls:
  • security control: Implement automated Static Application Security Testing (SAST) in the CI/CD pipeline to detect potential vulnerabilities in the code base before release.
  • security control: Implement automated Dependency Scanning to identify known vulnerabilities in third-party libraries used by phpspreadsheet.
  • security control: Consider implementing Dynamic Application Security Testing (DAST) to test the library's behavior in runtime environments, although this might be challenging for a library.
  • security control: Establish a clear vulnerability reporting and response process to handle security issues reported by the community or security researchers.
  • security control: Conduct regular security audits or penetration testing to proactively identify and address potential vulnerabilities.
  • security control: Provide security guidelines for developers using phpspreadsheet, emphasizing secure coding practices and input validation when using the library.
  • security control: Security awareness training for maintainers and contributors on secure coding practices and common web application vulnerabilities.
  • Security Requirements:
  • Authentication: Not directly applicable as phpspreadsheet is a library and does not handle user authentication itself. Applications using phpspreadsheet are responsible for their own authentication mechanisms.
  • Authorization: Not directly applicable as phpspreadsheet is a library and does not manage user authorization. Applications using phpspreadsheet are responsible for implementing appropriate authorization controls based on their business logic and data access requirements.
  • Input Validation: Critical. phpspreadsheet must robustly validate all input data, especially when parsing spreadsheet files from untrusted sources. This includes validating file formats, data types, data ranges, and preventing injection attacks (e.g., formula injection). Input validation should be implemented throughout the library, particularly in file readers and data parsing components.
  • Cryptography: Important for handling password-protected spreadsheet files and potentially for encrypting sensitive data within spreadsheets. phpspreadsheet should use secure cryptographic libraries and algorithms when dealing with encryption and decryption. Ensure proper key management and secure storage of cryptographic keys if implemented.

DESIGN

C4 CONTEXT

graph LR
    subgraph "Business User"
        BU("Business User")
    end
    subgraph "PHP Application"
        PA("PHP Application")
    end
    subgraph "File System"
        FS("File System")
    end
    subgraph "Database"
        DB("Database")
    end
    subgraph "Spreadsheet Software"
        SS("Spreadsheet Software")
    end
    center_box("phpspreadsheet")

    BU --> PA
    PA --> center_box
    center_box --> FS
    center_box --> DB
    center_box --> SS
    PA --> FS
    PA --> DB
    PA --> SS

    linkStyle 0,1,2,3,4,5,6,7,8,9 stroke:#333,stroke-width:2px;
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  • Context Diagram Elements:
    • Name: Business User
    • Type: Person
    • Description: End-users who interact with PHP applications that utilize phpspreadsheet to process spreadsheet data. They may be employees, customers, or partners of the business.
    • Responsibilities: Use PHP applications to create, view, edit, and manage spreadsheet data.
    • Security controls: User authentication and authorization within the PHP application. Access control lists to manage data access.
    • Name: PHP Application
    • Type: Software System
    • Description: Custom-built or third-party PHP applications that integrate phpspreadsheet to handle spreadsheet files. These applications provide business functionality to users.
    • Responsibilities: Utilize phpspreadsheet library to read, write, and manipulate spreadsheet data. Implement business logic related to spreadsheet processing. Manage user interactions and data presentation.
    • Security controls: Input validation of user-provided data. Secure coding practices in application development. Session management and protection against session hijacking. Protection against common web application vulnerabilities (OWASP Top 10).
    • Name: phpspreadsheet
    • Type: Software System
    • Description: The phpspreadsheet library itself, providing PHP classes and functions for working with spreadsheet files.
    • Responsibilities: Parsing and generating spreadsheet files in various formats (XLSX, CSV, ODS, etc.). Providing APIs for manipulating spreadsheet data (cells, rows, columns, sheets, formulas, styles). Handling file I/O operations related to spreadsheet files.
    • Security controls: Input validation of spreadsheet file content. Protection against formula injection and other spreadsheet-specific vulnerabilities. Secure handling of file operations.
    • Name: File System
    • Type: External System
    • Description: The file system where spreadsheet files are stored and accessed by PHP applications and phpspreadsheet. This could be local file storage, network file shares, or cloud storage services.
    • Responsibilities: Storing and retrieving spreadsheet files. Managing file permissions and access control. Ensuring data integrity and availability of files.
    • Security controls: File system access controls (permissions). Encryption of data at rest if required. Regular backups and disaster recovery mechanisms.
    • Name: Database
    • Type: External System
    • Description: Databases used by PHP applications to store and manage data, which may be imported from or exported to spreadsheet files using phpspreadsheet.
    • Responsibilities: Storing structured data. Providing data persistence and querying capabilities. Ensuring data integrity and availability.
    • Security controls: Database access controls and authentication. Data encryption in transit and at rest. Regular database backups. Protection against SQL injection vulnerabilities in PHP applications.
    • Name: Spreadsheet Software
    • Type: External System
    • Description: Desktop or web-based spreadsheet applications (e.g., Microsoft Excel, Google Sheets, LibreOffice Calc) used by business users to create, view, and edit spreadsheet files that are processed by PHP applications and phpspreadsheet.
    • Responsibilities: Creating and editing spreadsheet files. Providing user interface for spreadsheet manipulation. Supporting various spreadsheet file formats.
    • Security controls: File format validation. Protection against macro viruses and malicious content within spreadsheet files. User authentication and authorization for accessing spreadsheet software (if applicable, e.g., for web-based applications).

C4 CONTAINER

graph LR
    subgraph "PHP Application Runtime"
        subgraph "PHP Application Container"
            PA_COMP("PHP Application Code")
            PHPS("phpspreadsheet Library")
        end
    end

    PA_COMP -- uses --> PHPS

    linkStyle 0,1 stroke:#333,stroke-width:2px;
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  • Container Diagram Elements:
    • Name: PHP Application Container
    • Type: Container
    • Description: Represents the runtime environment where the PHP application code and the phpspreadsheet library are executed. This could be a web server (e.g., Apache, Nginx with PHP-FPM), a CLI environment, or a containerized environment (e.g., Docker).
    • Responsibilities: Executing PHP application code. Providing runtime environment for phpspreadsheet library. Handling HTTP requests (for web applications). Managing application dependencies.
    • Security controls: Operating system and runtime environment hardening. Web server security configurations. Regular patching of operating system and runtime components. Resource limits and isolation (e.g., using containers).
    • Name: PHP Application Code
    • Type: Component
    • Description: The custom PHP code of the application that utilizes the phpspreadsheet library to implement specific business logic and functionality related to spreadsheet processing.
    • Responsibilities: Implementing business logic. Interacting with phpspreadsheet API. Handling user requests and data presentation. Managing application-specific configurations and data.
    • Security controls: Secure coding practices. Input validation at the application level. Authorization checks based on business logic. Protection against application-specific vulnerabilities.
    • Name: phpspreadsheet Library
    • Type: Component
    • Description: The phpspreadsheet library code itself, consisting of PHP classes and functions for spreadsheet manipulation.
    • Responsibilities: Parsing and generating spreadsheet files. Providing API for spreadsheet operations. Handling file format specifics. Implementing core spreadsheet processing logic.
    • Security controls: Input validation within the library. Protection against spreadsheet-specific vulnerabilities (e.g., formula injection). Secure file handling within the library.

DEPLOYMENT

graph LR
    subgraph "Production Environment"
        subgraph "Web Server Instance"
            WS("Web Server (e.g., Apache, Nginx)")
            PHP_RUNTIME("PHP Runtime (e.g., PHP-FPM)")
            APP_CODE("PHP Application Code & phpspreadsheet")
        end
    end

    WS --> PHP_RUNTIME
    PHP_RUNTIME --> APP_CODE

    linkStyle 0,1,2 stroke:#333,stroke-width:2px;
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  • Deployment Diagram Elements:
    • Name: Production Environment
    • Type: Environment
    • Description: The target environment where the PHP application utilizing phpspreadsheet is deployed for live operation and user access. This is typically a server infrastructure managed by the organization.
    • Responsibilities: Hosting and running the PHP application. Providing necessary infrastructure resources (compute, storage, network). Ensuring application availability, performance, and security in a production setting.
    • Security controls: Network security controls (firewalls, intrusion detection/prevention systems). Server hardening and security configurations. Access control to production infrastructure. Monitoring and logging of security events. Incident response plan.
    • Name: Web Server Instance
    • Type: Node
    • Description: A single instance of a web server (e.g., Apache, Nginx) running in the production environment. It handles incoming HTTP requests and serves the PHP application.
    • Responsibilities: Receiving and processing HTTP requests. Serving static content. Forwarding dynamic requests to the PHP runtime. Load balancing (in multi-instance setups).
    • Security controls: Web server security configurations (e.g., disabling unnecessary modules, setting appropriate headers). HTTPS configuration for secure communication. Web application firewall (WAF) for protection against web attacks.
    • Name: PHP Runtime
    • Type: Node
    • Description: The PHP runtime environment (e.g., PHP-FPM) responsible for executing the PHP application code and the phpspreadsheet library.
    • Responsibilities: Executing PHP code. Managing PHP processes. Providing necessary PHP extensions and libraries.
    • Security controls: PHP runtime security configurations (e.g., disabling dangerous functions, setting appropriate resource limits). Regular patching of PHP runtime.
    • Name: PHP Application Code & phpspreadsheet
    • Type: Software Deployment Unit
    • Description: The deployed PHP application code, including the phpspreadsheet library, running within the PHP runtime environment.
    • Responsibilities: Implementing business logic. Utilizing phpspreadsheet for spreadsheet processing. Interacting with other systems and resources.
    • Security controls: Application-level security controls (as described in previous sections). Secure deployment practices. Regular application updates and patching.

BUILD

graph LR
    subgraph "Developer Workstation"
        DEV("Developer")
    end
    subgraph "Version Control System (GitHub)"
        VCS("GitHub Repository")
    end
    subgraph "CI/CD System (GitHub Actions)"
        CI("CI/CD Pipeline")
    end
    subgraph "Package Repository (Packagist)"
        PR("Packagist")
    end
    subgraph "Build Artifacts"
        BA("Build Artifacts (e.g., ZIP, Phar)")
    end

    DEV --> VCS
    VCS --> CI
    CI --> PR
    CI --> BA

    linkStyle 0,1,2,3,4 stroke:#333,stroke-width:2px;
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  • Build Process Elements:
    • Name: Developer
    • Type: Person
    • Description: Software developers who write code for phpspreadsheet, including bug fixes, new features, and security patches.
    • Responsibilities: Writing and testing code. Committing code changes to the version control system. Participating in code reviews.
    • Security controls: Secure coding practices. Code review process. Access control to the version control system.
    • Name: Version Control System (GitHub)
    • Type: System
    • Description: GitHub repository hosting the phpspreadsheet source code, issue tracking, and collaboration tools.
    • Responsibilities: Storing and managing source code. Tracking code changes and versions. Facilitating collaboration among developers.
    • Security controls: Access control to the repository (authentication and authorization). Branch protection rules. Audit logging of repository activities.
    • Name: CI/CD Pipeline (GitHub Actions)
    • Type: System
    • Description: Automated CI/CD pipeline using GitHub Actions to build, test, and publish phpspreadsheet releases.
    • Responsibilities: Automating build process. Running unit and integration tests. Performing static analysis and security scans. Building release artifacts. Publishing releases to package repositories (Packagist) and distribution channels.
    • Security controls: Secure CI/CD pipeline configuration. Access control to CI/CD system. Secrets management for credentials and API keys. Build environment security hardening. SAST and dependency scanning integrated into the pipeline.
    • Name: Package Repository (Packagist)
    • Type: System
    • Description: Packagist, the primary package repository for PHP libraries, used to distribute phpspreadsheet packages to PHP developers.
    • Responsibilities: Hosting and distributing phpspreadsheet packages. Managing package versions and dependencies. Providing package download and installation services.
    • Security controls: Package signing and verification. Malware scanning of uploaded packages. Access control to package management.
    • Name: Build Artifacts (e.g., ZIP, Phar)
    • Type: Data
    • Description: The packaged and built artifacts of phpspreadsheet, ready for distribution and use by PHP developers. These may include ZIP archives, Phar files, or Composer packages.
    • Responsibilities: Providing distributable versions of phpspreadsheet. Containing all necessary code and resources for the library.
    • Security controls: Integrity checks (e.g., checksums, signatures) for build artifacts. Secure storage and distribution of build artifacts.

RISK ASSESSMENT

  • Critical Business Processes:
  • Business processes that rely on accurate and reliable spreadsheet data processing, such as financial reporting, sales analysis, inventory management, data migration, and document generation. Disruption or corruption of these processes due to vulnerabilities in phpspreadsheet could have significant business impact.
  • Data to Protect and Sensitivity:
  • Spreadsheet data itself is the primary data to protect. The sensitivity of this data varies depending on the application using phpspreadsheet. It can range from publicly available data to highly sensitive business information, financial records, personal data, or confidential intellectual property. The sensitivity level should be determined based on the specific use case and data processed by applications using phpspreadsheet.

QUESTIONS & ASSUMPTIONS

  • BUSINESS POSTURE Questions & Assumptions:
  • assumption: The primary business goal is to provide a general-purpose PHP library for spreadsheet manipulation, catering to a wide range of business needs.
  • assumption: Business users rely on PHP applications that integrate phpspreadsheet for various data-driven tasks.
  • question: What are the specific industry verticals or use cases that phpspreadsheet targets most heavily? (e.g., finance, healthcare, education)
  • question: What is the expected scale of usage and performance requirements for applications using phpspreadsheet?
  • SECURITY POSTURE Questions & Assumptions:
  • assumption: The project follows standard open-source security practices, including code reviews and community contributions for security fixes.
  • assumption: Security is a concern, but not necessarily the top priority compared to functionality and ease of use for developers.
  • question: Are there any specific security certifications or compliance requirements that phpspreadsheet needs to meet? (e.g., SOC 2, HIPAA, GDPR)
  • question: What is the current process for handling vulnerability reports and releasing security patches?
  • DESIGN Questions & Assumptions:
  • assumption: phpspreadsheet is designed as a modular library with clear separation of concerns between different components (readers, writers, core engine, etc.).
  • assumption: The library is intended to be integrated into various PHP application architectures, from simple scripts to complex web applications.
  • question: Are there any specific architectural constraints or dependencies that impact the design of phpspreadsheet? (e.g., PHP version compatibility, external library dependencies)
  • question: What are the performance and scalability considerations in the design of phpspreadsheet, especially for handling large spreadsheet files?