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Mitigation Strategies Analysis for dart-lang/http

Mitigation Strategy: Validate Redirect URLs

Description:

  1. Intercept Redirects: Before the http package automatically follows a redirect (or before manually handling a 3xx response), obtain the Response object.
  2. Extract Location Header: Access the headers property of the Response object and retrieve the value of the Location header (the redirect URL).
  3. Whitelist Check: Compare the extracted URL against a predefined whitelist of allowed domains/URL patterns.
  4. Regex (Optional, Use with Caution): For complex patterns, use regular expressions, but be extremely careful to avoid ReDoS.
  5. Decision:
    • If the URL is in the whitelist, allow the redirect.
    • If the URL is not in the whitelist, reject the redirect. Log the event and prevent further interaction with the URL.
  6. Encoding: Ensure the URL is properly encoded.

Threats Mitigated:

  • Open Redirects (High Severity): Prevents redirection to malicious sites.
  • Phishing Attacks (High Severity): Reduces redirection to phishing sites.
  • Malware Distribution (High Severity): Prevents redirection to malware sites.
  • Session Hijacking (High Severity): Can help prevent session hijacking via manipulated redirects.

Impact:

  • Open Redirects: Risk almost eliminated (with correct implementation).
  • Phishing/Malware: Risk significantly reduced.
  • Session Hijacking: Risk reduced (with other session management).

Currently Implemented:

  • lib/network/http_client.dart - Basic check present (insufficient - checks only for "example.com").

Missing Implementation:

  • lib/network/api_client.dart - No redirect validation.
  • lib/auth/auth_manager.dart - No redirect validation after login (critical).
  • Comprehensive Whitelist: http_client.dart needs a robust whitelist and proper URL parsing.

Mitigation Strategy: Limit Maximum Redirects

Description:

  1. Identify http Usage: Locate all http request calls (e.g., http.get, http.post, Client.send).
  2. Set maxRedirects: Set the maxRedirects parameter to a low value (e.g., 3-5) for each request:
    • Directly in the request method (e.g., http.get(url, maxRedirects: 3)).
    • In a custom Client (e.g., final client = http.Client(); client.maxRedirects = 3;).
  3. Handle RedirectLimitExceededException: Use try...catch to catch RedirectLimitExceededException.
  4. Logging: Log exception details (original URL, redirect count).
  5. User Notification (Optional): Consider displaying an error message.

Threats Mitigated:

  • Redirect Loops (Medium Severity): Prevents infinite redirect loops.
  • Denial of Service (DoS) (Medium Severity): Limits resource consumption from excessive redirects.
  • Evasion Techniques (Medium Severity): Makes it harder for attackers to evade detection with long redirect chains.

Impact:

  • Redirect Loops: Risk eliminated.
  • DoS: Risk significantly reduced.
  • Evasion Techniques: Risk moderately reduced.

Currently Implemented:

  • lib/network/http_client.dart - maxRedirects is set globally to 10 (too high).

Missing Implementation:

  • lib/network/api_client.dart - No maxRedirects set.
  • lib/auth/auth_manager.dart - No maxRedirects set.
  • Exception Handling: No try...catch for RedirectLimitExceededException.
  • Reduce Global Value: Reduce global maxRedirects in http_client.dart (e.g., to 3).

Mitigation Strategy: Rely on System Root CAs (and Implement Strict badCertificateCallback if Necessary)

Description:

  1. Default Behavior: Prioritize using the system's trusted root CA store (Dart http's default).
  2. Avoid Overrides: Do not use SecurityContext to manually load certificates or disable validation unless absolutely necessary (testing only).
  3. badCertificateCallback (If Necessary): If overriding, use badCertificateCallback in IOClient. Never return true unconditionally in production.
  4. Strict Checks within badCertificateCallback:
    • Certificate Pinning: Compare the certificate (or its hash) to a known, trusted certificate.
    • Hostname Verification: Verify the certificate's CN/SAN matches the hostname.
    • Expiration Check: Ensure the certificate is not expired.
    • Issuer Verification: If applicable, verify the issuer.
  5. Logging: Always log certificate errors, even if handled in badCertificateCallback.

Threats Mitigated:

  • Man-in-the-Middle (MitM) Attacks (High Severity): Prevents traffic interception with fake certificates.
  • Data Breaches (High Severity): Protects sensitive data transmitted over HTTPS.
  • Impersonation (High Severity): Prevents attackers from impersonating servers.

Impact:

  • MitM Attacks: Risk almost eliminated (with correct certificate pinning).
  • Data Breaches/Impersonation: Risk significantly reduced.

Currently Implemented:

  • The project relies on system root CAs (good).
  • test/network/http_client_test.dart - Uses badCertificateCallback (insecure - returns true unconditionally).

Missing Implementation:

  • Secure badCertificateCallback in Tests: http_client_test.dart needs a secure implementation (e.g., certificate pinning).
  • No SecurityContext Misuse: Code review to confirm no SecurityContext misuse in production.

Mitigation Strategy: Avoid Ambiguous HTTP Headers

Description:

  1. Rely on http Defaults: The http package handles headers like Content-Length and Transfer-Encoding correctly. Avoid manual manipulation.
  2. Review Custom Headers: If setting custom headers, ensure they are unambiguous and don't conflict with standards.
  3. Consistent Content-Length: If manually set, ensure it's accurate.
  4. Avoid Transfer-Encoding: chunked Manipulation: Don't manually set or modify this unless implementing chunked encoding yourself.
  5. Use Standard Methods: Stick to standard HTTP methods.

Threats Mitigated:

  • HTTP Request Smuggling (Medium Severity): Reduces the chance of triggering vulnerabilities in proxies/load balancers.

Impact:

  • HTTP Request Smuggling: Risk moderately reduced (primarily a server-side issue).

Currently Implemented:

  • The project appears to rely on http package defaults (good).

Missing Implementation:

  • Code Review: Confirm no unsafe custom header manipulation.

Mitigation Strategy: Use Standard Authorization Headers and Review Custom Headers

Description:

  1. Authorization Header: Use the standard Authorization header for authentication (e.g., Bearer <token>, Basic <credentials>).
  2. Avoid Custom Auth Headers: Do not create custom headers for credentials.
  3. Review All Custom Headers: Ensure no custom headers contain sensitive information.
  4. HTTPS: Always use HTTPS.

Threats Mitigated:

  • Data Leakage (High Severity): Prevents sensitive information in headers.
  • Credential Theft (High Severity): Reduces risk of credential theft.

Impact:

  • Data Leakage/Credential Theft: Risk significantly reduced.

Currently Implemented:

  • lib/auth/auth_manager.dart - Uses Authorization header with Bearer (good).

Missing Implementation:

  • Code Review: Ensure no other parts set custom headers with sensitive data.

Mitigation Strategy: Validate Response Status Codes and Body

Description:

  1. Check Status Code: After a request (especially POST/PUT/PATCH/DELETE), check the Response object's statusCode.
  2. Handle Error Codes: Implement logic for different status codes:
    • 2xx (Success): Process the response body (if any).
    • 4xx (Client Error): Log, notify the user (if applicable), and do not modify data based on the response.
    • 5xx (Server Error): Log, notify the user, consider retrying (with backoff).
  3. Validate Response Body: If the server returns data, validate it before use:
    • Parse JSON Safely: Use jsonDecode, handle FormatException.
    • Type Checking: Verify data types.
    • Value Validation: Check values are within expected ranges/patterns.
  4. Idempotency: Design requests to be idempotent.

Threats Mitigated:

  • Unintentional Data Modification (Medium Severity): Prevents modification based on unexpected responses.
  • Data Corruption (Medium Severity): Reduces risk of data corruption.
  • Logic Errors (Medium Severity): Prevents logic errors from processing bad responses.

Impact:

  • Unintentional Modification/Corruption: Risk significantly reduced.
  • Logic Errors: Risk moderately reduced.

Currently Implemented:

  • lib/network/api_client.dart - Checks for 200 status but not others. No response body validation.

Missing Implementation:

  • Comprehensive Status Code Handling: api_client.dart needs to handle all status codes (4xx, 5xx).
  • Response Body Validation: api_client.dart needs to validate response bodies.
  • Error Handling: Implement error handling for non-2xx codes.
  • Idempotency: Review API design and implement idempotency.