attack-surface.md

Attack Surface Analysis for dart-lang/shelf

Attack Surface: Middleware Vulnerabilities

Description: Exploitation of security flaws within custom or third-party middleware integrated into a shelf application's request pipeline.

• Shelf Contribution: shelf's core design relies on a composable middleware pipeline. This architecture directly incorporates the security posture of each middleware component. Vulnerabilities in middleware become vulnerabilities in the shelf application itself. shelf's pipeline facilitates the inclusion of potentially vulnerable middleware.
• Example: A custom authentication middleware used in a shelf application has a coding error that allows bypassing authentication checks. An attacker exploits this flaw to gain unauthorized access to protected resources served by the shelf application.
• Impact: Unauthorized access to sensitive data and application functionality, data breaches, data manipulation, potential for full application compromise depending on the middleware's role.
• Risk Severity: Critical
• Mitigation Strategies:
  • Rigorous Middleware Auditing: Conduct thorough security audits and code reviews of all middleware, especially custom or less established third-party middleware, before integrating them into the shelf pipeline.
  • Principle of Least Privilege for Middleware: Design and configure middleware to operate with the minimum necessary permissions and access to resources to limit the impact of potential vulnerabilities.
  • Dependency Management and Updates: Maintain a strict dependency management policy and promptly update middleware libraries to patch known security vulnerabilities.
  • Security Testing of Middleware Pipeline: Include the entire middleware pipeline in security testing efforts, such as penetration testing and static analysis, to identify vulnerabilities in middleware interactions and configurations.

Attack Surface: Middleware Ordering Issues Leading to Security Bypass

Description: Critical security vulnerabilities arising from an incorrect or insecure order of middleware within a shelf application's Pipeline, leading to the circumvention of security controls.

• Shelf Contribution: shelf's Pipeline explicitly defines the sequence of middleware execution. The developer's responsibility to correctly order middleware is a direct aspect of using shelf. Incorrect ordering directly undermines the intended security architecture built with shelf's middleware.
• Example: Logging middleware is mistakenly placed before authentication middleware in a shelf pipeline. An attacker can send requests to protected endpoints, and the request details (potentially including sensitive information) are logged before authentication is performed. More critically, if authorization middleware is placed after request processing middleware, unauthorized actions might be executed before access control is enforced.
• Impact: Complete bypass of intended security controls (authentication, authorization, input validation), unauthorized access to sensitive resources and functionality, data breaches, data manipulation, potential for full application compromise.
• Risk Severity: Critical
• Mitigation Strategies:
  • Security-First Middleware Pipeline Design: Design the shelf middleware pipeline with security as the primary consideration. Place security-critical middleware (authentication, authorization, input validation, security headers) at the beginning of the pipeline to ensure they are executed first.
  • Explicitly Document Middleware Order Rationale: Clearly document the intended order of middleware in the shelf pipeline and the security reasoning behind this order. This documentation should be reviewed and updated as the application evolves.
  • Automated Testing of Middleware Order: Implement automated tests that specifically verify the correct execution order of middleware and validate that security middleware is effectively applied before request processing logic.
  • Regular Security Reviews of Pipeline Configuration: Conduct periodic security reviews of the shelf middleware pipeline configuration to ensure the order remains secure and aligned with the application's security requirements, especially after any changes or additions to the middleware stack.

Attack Surface: Insecure shelf.serve Usage - Lack of HTTPS/TLS

Description: Critical vulnerability resulting from deploying a shelf application handling sensitive data over HTTP instead of HTTPS/TLS when using shelf.serve or related server setup.

• Shelf Contribution: shelf.serve is the primary function provided by shelf to run a shelf handler on an HttpServer. While shelf itself doesn't enforce secure transport, the direct use of shelf.serve without explicit HTTPS configuration for sensitive applications is a critical misstep in deploying a shelf-based application securely. The ease of use of shelf.serve can inadvertently lead to insecure deployments if developers overlook HTTPS configuration.
• Example: A shelf application managing user accounts and financial transactions is deployed using shelf.serve over HTTP. An attacker on a shared network can intercept user credentials, session tokens, and transaction details transmitted in plain text, leading to account compromise and financial fraud.
• Impact: Complete loss of data confidentiality and integrity, eavesdropping on all communication, man-in-the-middle attacks, session hijacking, account compromise, data breaches, severe reputational damage.
• Risk Severity: Critical
• Mitigation Strategies:
  • Mandatory HTTPS/TLS Enforcement: Always configure shelf applications to use HTTPS/TLS for all production deployments, especially when handling any form of sensitive data, authentication credentials, or user sessions.
  • Explicit HTTPS Configuration in Deployment: Ensure that the deployment process for shelf applications includes explicit steps for configuring HTTPS, including obtaining and installing valid TLS certificates and configuring the server to use HTTPS.
  • Automated HTTPS Checks: Implement automated checks in deployment pipelines to verify that HTTPS is correctly configured and enforced for shelf applications before they are deployed to production environments.
  • Educate Developers on Secure Deployment Practices: Provide comprehensive training and documentation to developers on secure deployment practices for shelf applications, emphasizing the critical importance of HTTPS and secure server configuration when using shelf.serve.