threat-modeling.md

Threat Model Analysis for expressjs/express

Threat: Route Parameter Pollution/Injection

• Description: An attacker manipulates URL route parameters by injecting malicious code or unexpected values through crafted URLs. This can lead to unauthorized data access, modification, or execution of unintended code if parameters are not properly validated and sanitized before being used in backend logic, such as database queries or system commands.
• Impact: Data breach, data manipulation, unauthorized access to resources, potential Remote Code Execution (RCE) depending on the application logic.
• Affected Express Component: express.Router, Route handlers, Request parameters (req.params)
• Risk Severity: High
• Mitigation Strategies:
  • Input Validation: Implement robust input validation for all route parameters using libraries like Joi or express-validator.
  • Parameter Sanitization: Sanitize route parameters before using them in backend operations.
  • Parameterized Queries/ORMs: Use parameterized queries or ORMs to prevent SQL injection when interacting with databases.
  • Principle of Least Privilege: Grant minimal necessary permissions to database users and application components.

Threat: Vulnerable or Outdated Middleware

• Description: An attacker exploits known vulnerabilities in outdated or insecure third-party middleware packages used in the Express application. They can leverage publicly disclosed vulnerabilities in these middleware components to compromise the application, potentially gaining unauthorized access, executing malicious code, or causing a DoS.
• Impact: Wide range of impacts depending on the vulnerability, including Remote Code Execution (RCE), data breach, data manipulation, Denial of Service (DoS).
• Affected Express Component: Middleware ecosystem, npm dependencies, package.json
• Risk Severity: High to Critical
• Mitigation Strategies:
  • Dependency Auditing: Regularly audit application dependencies using npm audit or yarn audit.
  • Dependency Updates: Keep all middleware dependencies updated to their latest versions.
  • Security Scanning: Integrate dependency scanning into the CI/CD pipeline.
  • Vulnerability Monitoring: Continuously monitor for new vulnerabilities in used middleware packages.

Threat: Middleware Misconfiguration and Ordering Issues

• Description: An attacker exploits incorrect configuration or improper ordering of middleware in the Express application's pipeline. By understanding the middleware execution order, they can craft requests that bypass security middleware (like authentication or sanitization) or trigger unintended behavior due to misconfigured middleware interactions.
• Impact: Security bypasses, unauthorized access, data leakage, unexpected application behavior.
• Affected Express Component: app.use(), Middleware pipeline, Middleware configuration
• Risk Severity: High
• Mitigation Strategies:
  • Middleware Pipeline Planning: Carefully plan and document the middleware pipeline and execution order.
  • Security Middleware Placement: Ensure security-related middleware are placed strategically early in the pipeline.
  • Configuration Review: Thoroughly review middleware configurations for correctness.
  • Testing Middleware Interactions: Test the entire middleware pipeline to verify intended behavior.

Threat: Directory Traversal via express.static Misconfiguration

• Description: An attacker exploits misconfiguration of express.static middleware to access files outside the intended static file directory. By crafting specific URLs with directory traversal sequences (e.g., ../), they can navigate the file system and potentially access sensitive application files, configuration files, or even application code.
• Impact: Information disclosure, unauthorized access to sensitive files, potential exposure of application source code or configuration.
• Affected Express Component: express.static middleware, Static file serving configuration
• Risk Severity: High
• Mitigation Strategies:
  • Restrict Static Directory: Carefully configure express.static to serve only the intended static file directory, avoiding the application root.
  • Path Sanitization (Default Express): Rely on Express.static's default directory traversal prevention.
  • Testing Static File Serving: Test static file serving configurations to ensure directory traversal is not possible.

Threat: Serving Sensitive Files as Static Content

• Description: An attacker gains unauthorized access to sensitive files by exploiting accidental placement of these files within the static file directory served by express.static. If developers mistakenly place files like .env files, backup files, or database credentials in the static directory, they become publicly accessible through the web server.
• Impact: Information disclosure, exposure of sensitive credentials, potential full application compromise depending on the exposed files.
• Affected Express Component: express.static middleware, Static file directory, File system
• Risk Severity: Critical
• Mitigation Strategies:
  • Secure Static Directory Management: Carefully manage static file directories and ensure they do not contain sensitive files.
  • .gitignore and File Exclusion: Use .gitignore to prevent accidental inclusion of sensitive files in static directories.
  • Separate Sensitive Data: Store sensitive data outside of static file directories, using environment variables or configuration management.
  • Regular Audits: Regularly audit static file directories to identify and remove any inadvertently placed sensitive files.

Threat: Vulnerabilities in Body-parser or Similar Middleware

• Description: An attacker exploits known vulnerabilities in body-parser or other body parsing middleware used by the Express application. These vulnerabilities, such as prototype pollution or buffer overflow issues, can be leveraged through crafted request bodies to compromise the application, potentially leading to Remote Code Execution (RCE) or other security breaches.
• Impact: Wide range of impacts depending on the vulnerability, including Remote Code Execution (RCE), data breach, data manipulation, Denial of Service (DoS).
• Affected Express Component: body-parser middleware, Request body parsing, npm dependencies
• Risk Severity: High to Critical
• Mitigation Strategies:
  • Dependency Updates: Keep body-parser and other body parsing middleware updated to the latest versions.
  • Dependency Auditing: Regularly audit application dependencies using npm audit or yarn audit.
  • Security Scanning: Integrate dependency scanning into the CI/CD pipeline.
  • Vulnerability Monitoring: Continuously monitor for new vulnerabilities in used body parsing middleware.