threat-modeling.md

Threat Model Analysis for actix/actix-web

Threat: Actor Mailbox Overflow

• Threat: Actor Mailbox Overflow DoS
• Description: An attacker sends a large number of messages to a specific actor, exceeding the mailbox capacity. The attacker might identify a particularly slow or resource-intensive actor and target it. They could use automated tools to generate a high volume of requests that trigger messages to this actor.
• Impact: Denial of service (DoS). The targeted actor, and potentially the entire application, becomes unresponsive. Requests may time out, and new requests may be rejected.
• Affected Component: actix::Actor, actix::Addr, actix::Context, message handlers (methods decorated with #[actix::main] or similar).
• Risk Severity: High
• Mitigation Strategies:
  • Use bounded mailboxes: Configure a maximum size for actor mailboxes using Context::set_mailbox_capacity.
  • Implement backpressure: Use mechanisms like Context::wait or stream processing to handle message bursts gracefully.
  • Rate limiting: Implement rate limiting at the application level (e.g., using middleware) to limit the number of requests that can trigger messages to vulnerable actors.
  • Asynchronous processing: Ensure message handlers are asynchronous and avoid blocking operations.

Threat: Actor Race Condition

• Threat: Actor Race Condition Data Corruption
• Description: An attacker might exploit timing vulnerabilities in the application's logic if multiple actors attempt to modify shared state concurrently without proper synchronization. This is less about a direct attack and more about exploiting existing flaws in the application's design. The attacker might try to trigger specific sequences of requests that are likely to expose race conditions.
• Impact: Data corruption, inconsistent application state, unpredictable behavior, potentially leading to crashes or security vulnerabilities.
• Affected Component: actix::Actor, any shared mutable state accessed by multiple actors (should be avoided), synchronization primitives (if used incorrectly).
• Risk Severity: High
• Mitigation Strategies:
  • Minimize shared mutable state: Design actors to be as isolated as possible.
  • Message passing: Prefer message passing for inter-actor communication instead of shared state.
  • Immutable data: Use immutable data structures whenever possible.
  • Synchronization: If shared mutable state is unavoidable, use appropriate synchronization primitives (e.g., Mutex, RwLock) correctly, paying close attention to deadlock avoidance.
  • Thorough testing: Conduct rigorous testing, including concurrency testing, to identify and fix race conditions.

Threat: Dependency Vulnerability (Actix-Web or its Dependencies)

• Threat: Exploitation of Vulnerability in Actix-Web or Dependencies
• Description: An attacker exploits a known vulnerability in Actix-Web itself, or in one of its dependencies (e.g., tokio, hyper, serde, etc.). The attacker might use publicly available exploit code or develop their own exploit based on vulnerability disclosures.
• Impact: Varies widely depending on the vulnerability. Could range from denial of service (DoS) to remote code execution (RCE), data breaches, or privilege escalation.
• Affected Component: Potentially any part of the Actix-Web framework or its dependencies.
• Risk Severity: Critical
• Mitigation Strategies:
  • Regular updates: Keep Actix-Web and all dependencies updated to the latest versions.
  • Vulnerability scanning: Use tools like cargo audit, Snyk, or Dependabot to automatically detect known vulnerabilities.
  • SBOM: Maintain a Software Bill of Materials (SBOM) to track all dependencies.
  • Security advisories: Monitor security advisories for Actix-Web and its dependencies.

Threat: Middleware Bypass

• Threat: Middleware Bypass or Misconfiguration
• Description: An attacker crafts a request that bypasses security checks implemented in middleware, or exploits a misconfiguration in the middleware. This could involve manipulating headers, URLs, or request bodies. Incorrect ordering of middleware is a common cause.
• Impact: Unauthorized access to resources, data leakage, privilege escalation, or other security breaches.
• Affected Component: actix_web::middleware, custom middleware implementations.
• Risk Severity: High
• Mitigation Strategies:
  • Correct middleware order: Ensure security-related middleware (authentication, authorization) is applied before middleware that accesses protected resources.
  • Thorough testing: Test middleware extensively, including negative test cases to ensure it cannot be bypassed.
  • Input validation: Validate and sanitize all input within middleware.
  • Least privilege: Middleware should only have access to the resources it needs.
  • Secure coding practices: Follow secure coding practices when developing custom middleware.

Threat: Unvalidated WebSocket Data

• Threat: Unvalidated WebSocket Data Injection
• Description: An attacker sends malicious data over an established WebSocket connection. This data is not properly validated or sanitized by the server, leading to vulnerabilities like cross-site scripting (XSS) if the data is reflected back to other clients, or other injection attacks.
• Impact: Depends on the vulnerability. Could include XSS, command injection, data corruption, or other security breaches.
• Affected Component: WebSocket handler functions, actix_web::web::Payload.
• Risk Severity: High
• Mitigation Strategies:
  • Input validation: Validate and sanitize all data received over WebSocket connections.
  • Output encoding: Encode data appropriately before sending it over WebSocket connections, especially if it originated from user input.
  • Content Security Policy (CSP): Use CSP to mitigate XSS vulnerabilities.