mitigations.md

Mitigation Strategies Analysis for getstream/stream-chat-flutter

Mitigation Strategy: Secure Backend Token Generation (for stream-chat-flutter)

1. Mitigation Strategy: Secure Backend Token Generation (for stream-chat-flutter)

• Description:

  1. User Authentication: The user attempts to log in to the application.
  2. Backend Validation: Your backend verifies the user's credentials.
  3. Stream Token Request (Backend): Your backend uses the Stream server-side SDK. It calls the createUserToken method (or equivalent) using your Stream API secret key.
  4. Token Generation (Stream Server): The Stream server generates a signed JWT.
  5. Token Response (Backend): The Stream server returns the token to your backend.
  6. Secure Token Delivery: Your backend sends the token to the Flutter application over HTTPS.
  7. Client-Side Initialization (Flutter): The Flutter application receives the token and uses it to initialize the StreamChatClient:

     final client = StreamChatClient(
       'YOUR_API_KEY', // Public API key, *not* the secret.
       logLevel: Level.INFO,
     );
     
     await client.connectUser(
       User(id: 'user-id'),
       'THE_TOKEN_FROM_YOUR_BACKEND',
     );

  8. Token Refresh (Backend & Client): Your backend provides a refresh endpoint. The Flutter app periodically calls this endpoint (using client.connectUser again with the new token) before the current token expires.

• Threats Mitigated:

  • Threat: Client-side token generation within stream-chat-flutter.
    • Severity: Critical. Allows attackers to forge tokens and impersonate any user, bypassing all Stream security.
    • Impact: Completely eliminates this risk by ensuring tokens are only generated on the secure backend.
  • Threat: Exposure of Stream API Secret (if it were mistakenly used in the Flutter app).
    • Severity: Critical. Grants full control over your Stream application.
    • Impact: Prevents accidental exposure by ensuring the secret is never present in the client-side code.

• Impact: This is the most critical mitigation specific to stream-chat-flutter. It's the foundation of secure authentication and authorization.

• Currently Implemented: [Example: Yes, implemented. The AuthService in our Flutter app retrieves tokens from the /auth/login and /auth/refresh endpoints of our backend. client.connectUser is used with the retrieved token.]

• Missing Implementation: [Example: The refresh logic in AuthService doesn't handle network errors gracefully. We need to add retry logic and error handling to ensure the user stays connected.]

Mitigation Strategy: Granular Permissions with Stream Roles (Used by stream-chat-flutter)

2. Mitigation Strategy: Granular Permissions with Stream Roles (Used by stream-chat-flutter)

• Description:

  1. Identify User Roles: Define specific user roles beyond Stream's defaults (e.g., "standard_user," "moderator," "guest").
  2. Define Permissions: For each role, determine the precise actions they can perform within Stream Chat (create channels, send messages, read messages, delete messages, etc.).
  3. Configure Roles (Stream Dashboard/SDK): Use the Stream Dashboard or server-side SDK to create roles and assign permissions.
  4. Assign Roles in Token (Backend): When your backend generates the user token (see Mitigation #1), it must include the correct role for the user in the token's claims. This is how stream-chat-flutter enforces permissions.
  5. stream-chat-flutter Enforcement: The stream-chat-flutter SDK, based on the role in the token, automatically restricts the user's actions to those allowed by their role. You don't need to write custom client-side permission checks.
  6. Regular Review: Periodically review the roles and permissions in the Stream Dashboard.

• Threats Mitigated:

  • Threat: Overly permissive default roles within Stream.
    • Severity: High. Default roles might grant excessive permissions.
    • Impact: Reduces risk by ensuring users have only the minimum necessary permissions, enforced by stream-chat-flutter.
  • Threat: Unauthorized actions by compromised accounts (limited by role).
    • Severity: Medium-High. Even with a compromised token, the attacker's actions are restricted by the role in the token.
    • Impact: Limits the damage a compromised account can do, as stream-chat-flutter enforces the role-based restrictions.

• Impact: Implements the principle of least privilege within the context of Stream Chat, leveraging the SDK's built-in permission enforcement.

• Currently Implemented: [Example: We have "user" and "moderator" roles defined in Stream. The backend sets the role claim in the JWT. The Flutter app doesn't have any custom permission checks; it relies on Stream.]

• Missing Implementation: [Example: We need to add a "guest" role with read-only access. We also need to document the exact permissions for each role more clearly.]

Mitigation Strategy: Keep stream-chat-flutter Updated

3. Mitigation Strategy: Keep stream-chat-flutter Updated

• Description:

  1. Regular Checks: Periodically check for updates to the stream-chat-flutter package using pub outdated.
  2. Review Changelogs: Before updating, review the changelog for security-related fixes.
  3. Test Updates: Test updates in a development/staging environment before deploying to production. This is crucial for an SDK like this, as updates can affect core functionality.

• Threats Mitigated:

  • Threat: Exploitation of known vulnerabilities within the stream-chat-flutter SDK itself.
    • Severity: Variable (Low to Critical), depending on the vulnerability. Could range from minor UI glitches to major security flaws.
    • Impact: Reduces the risk by applying security patches provided by the Stream team.
  • Threat: Vulnerabilities in the SDK's dependencies.
    • Severity: Variable.
    • Impact: Updating stream-chat-flutter often updates its dependencies, mitigating vulnerabilities in those libraries.

• Impact: Directly addresses vulnerabilities within the SDK, which is essential for maintaining the security of your chat integration.

• Currently Implemented: [Example: We check for updates weekly and test in our staging environment.]

• Missing Implementation: [Example: We don't have automated alerts for new stream-chat-flutter releases. We should set that up.]