threat-modeling.md

Threat Model Analysis for thephpleague/flysystem

Threat: Storage Adapter Exploitation

• Description: An attacker exploits a vulnerability in a Flysystem adapter or its underlying storage system client library. This could involve sending crafted requests to the storage system through the adapter, leveraging known bugs in the adapter's code, or exploiting weaknesses in the storage system's API interaction.
• Impact:
  • Unauthorized access to stored data (read, modify, delete).
  • Data breach and confidentiality loss.
  • Data integrity compromise.
  • Denial of service against the storage system.
  • Potential for lateral movement if the compromised storage system is part of a larger infrastructure.
• Flysystem Component Affected: Specific Flysystem Adapter (e.g., S3 Adapter, Local Adapter, FTP Adapter) and potentially underlying storage client libraries.
• Risk Severity: Critical
• Mitigation Strategies:
  • Keep Flysystem and adapter dependencies updated: Regularly update Flysystem and all adapter libraries to the latest versions to patch known vulnerabilities.
  • Choose reputable adapters: Select adapters from trusted sources with active maintenance and security records.
  • Security Audits: Conduct security audits of the application and its Flysystem integration, including adapter configurations and usage.
  • Input Validation: Implement input validation and sanitization for adapter-specific configurations and parameters.
  • Vulnerability Scanning: Use vulnerability scanning tools to identify known vulnerabilities in Flysystem and its dependencies.

Threat: Insecure Adapter Configuration

• Description: An attacker exploits insecure configurations of Flysystem adapters, specifically focusing on exposure of sensitive credentials. This could involve gaining access to exposed credentials (e.g., cloud storage access keys, database passwords) stored insecurely in configuration files or environment variables.
• Impact:
  • Unauthorized access to stored data.
  • Data breach and confidentiality loss.
  • Data manipulation or deletion.
  • Account takeover of storage accounts.
  • Resource abuse and financial impact (e.g., in cloud storage scenarios).
• Flysystem Component Affected: Adapter Configuration (e.g., credentials, access keys, bucket names, paths, permissions).
• Risk Severity: High
• Mitigation Strategies:
  • Secure Credential Management: Store adapter credentials securely using dedicated secrets management systems (like HashiCorp Vault, AWS Secrets Manager), or secure environment variable handling. Avoid hardcoding credentials in code or configuration files.
  • Principle of Least Privilege: Configure adapter access permissions with the principle of least privilege. Grant only necessary permissions to the application.
  • Regular Configuration Audits: Regularly review and audit adapter configurations to ensure they adhere to security best practices and are not overly permissive.
  • Secure Protocols: Enforce secure protocols (HTTPS, SFTP, etc.) for adapter communication.
  • Configuration Validation: Implement validation checks for adapter configurations during application setup and deployment.

Threat: Path Traversal Vulnerabilities

• Description: An attacker crafts malicious input (filenames, paths) used in Flysystem file operations (read, write, delete, etc.) to bypass intended directory restrictions and access or manipulate files outside of the designated storage area. This is typically achieved by using path traversal sequences like ../ in user-controlled input.
• Impact:
  • Unauthorized access to sensitive files on the storage system.
  • Data breach and confidentiality loss.
  • Data manipulation or deletion of arbitrary files.
  • Potential for code execution if attacker can upload and access executable files in unintended locations (especially relevant for local filesystem adapter).
• Flysystem Component Affected: File path handling within Flysystem operations (e.g., read(), write(), delete(), copy(), move()).
• Risk Severity: Critical
• Mitigation Strategies:
  • Strict Input Validation and Sanitization: Thoroughly validate and sanitize all user-supplied input used in file paths.
  • Input Whitelisting: Use whitelisting to allow only permitted characters and path components in filenames and paths. Reject any input that does not conform to the whitelist.
  • Path Canonicalization: Canonicalize paths to resolve symbolic links and remove redundant path separators before using them in Flysystem operations.
  • UUIDs/Hashes for Filenames: Use UUIDs or hashes for internal filenames to decouple them from user-provided names and reduce path traversal risks.
  • Chroot Environments (Local Adapter): For sensitive applications using the local adapter, consider implementing chroot-like environments or operating system-level file system access restrictions to limit the application's access scope.
  • Avoid User-Controlled Paths: Minimize or eliminate user control over file paths whenever possible. If user input is necessary, process it carefully and restrict its influence on the final path.

Threat: Unrestricted Malicious File Uploads

• Description: An attacker uploads malicious files (e.g., malware, viruses, web shells) through unrestricted file upload functionality facilitated by Flysystem. These files can then be executed on the server or downloaded by other users, leading to system compromise or malware propagation.
• Impact:
  • Malware distribution (viruses, trojans, ransomware).
  • System compromise and potential remote code execution.
  • Spread of infections to users downloading malicious files.
  • Reputational damage and loss of user trust.
• Flysystem Component Affected: File upload functionality utilizing Flysystem's writeStream() or put() operations.
• Risk Severity: High
• Mitigation Strategies:
  • File Type Validation: Implement strict file type validation based on file extensions, MIME types (from Content-Type header and ideally using magic number detection), and potentially file content analysis.
  • File Size Limits: Enforce reasonable file size limits to prevent storage exhaustion and DoS attacks.
  • Filename Sanitization: Sanitize filenames to prevent path traversal and other injection attacks.
  • Store Uploads Outside Web Root: Store uploaded files outside the web root to prevent direct execution of uploaded scripts.
  • Virus Scanning: Implement robust virus scanning on uploaded files before processing or serving them.
  • Content Security Policy (CSP): Implement CSP to mitigate risks if uploaded content is served directly.

Threat: Dependency Vulnerabilities in Flysystem and its Dependencies

• Description: An attacker exploits known, high severity vulnerabilities in the Flysystem library itself or its critical dependencies. This could involve leveraging publicly disclosed vulnerabilities to achieve remote code execution, bypass security controls, or cause significant application disruption.
• Impact:
  • Application compromise and potential remote code execution.
  • Data breach and unauthorized access to sensitive information.
  • Denial of service and application downtime.
  • Privilege escalation and unauthorized administrative access.
• Flysystem Component Affected: Flysystem library core and its dependencies (including adapter libraries and other third-party libraries).
• Risk Severity: Critical
• Mitigation Strategies:
  • Regular Updates: Regularly update Flysystem and all its dependencies to the latest versions immediately after security updates are released. This is the most critical mitigation.
  • Dependency Monitoring: Monitor security advisories and vulnerability databases specifically for Flysystem and its direct and transitive dependencies.
  • Dependency Scanning Tools: Use dependency scanning tools (e.g., OWASP Dependency-Check, Snyk, Dependabot) configured to identify and alert on high and critical severity vulnerabilities in dependencies.
  • Security Audits: Include thorough dependency checks in regular security audits of the application, prioritizing Flysystem and its related libraries.
  • Software Composition Analysis (SCA): Implement SCA practices to continuously manage and track dependencies and their vulnerabilities throughout the software development lifecycle, with a focus on rapid response to critical vulnerabilities.