mitigations.md

Mitigation Strategies Analysis for egulias/emailvalidator

Mitigation Strategy: Implement Validation Timeouts

• Description:

  1. Identify the code sections where you are calling the emailvalidator library to validate email addresses.
  2. Implement a timeout mechanism around the emailvalidator validation process.
  3. The timeout duration should be set to a reasonable value that allows legitimate email addresses to be validated under normal conditions but is short enough to prevent excessive resource consumption in case of a ReDoS attack. A few seconds (e.g., 1-3 seconds) might be a good starting point, depending on your application's performance characteristics.
  4. If the validation process exceeds the timeout, interrupt it and treat it as a validation failure.
  5. Log timeout events for monitoring and potential incident response.

• Threats Mitigated:

  • Regular Expression Denial of Service (ReDoS): Severity: High. Even if input length limits are in place, complex ReDoS patterns might still cause slow validation. Timeouts provide a last line of defense specifically for emailvalidator's regex processing.

• Impact:

  • ReDoS: Impact: High. Significantly reduces the impact of ReDoS attacks originating from vulnerabilities within emailvalidator's regex engine by preventing them from consuming excessive server resources. The application remains responsive even under attack.

• Currently Implemented:

  • Validation timeouts are implemented in the user registration process within RegistrationService.php using PHP's set_time_limit() function before calling emailvalidator.

• Missing Implementation:

  • Validation timeouts are missing in the contact form processing logic in ContactService.php.
  • Validation timeouts are missing in the profile update process in ProfileService.php.
  • Validation timeouts are not implemented in any background jobs or asynchronous tasks that might use emailvalidator for email validation.

Mitigation Strategy: Regularly Update emailvalidator

• Description:

  1. Establish a process for regularly checking for updates to the egulias/emailvalidator library. This should be part of your regular dependency management and security patching routine.
  2. Monitor the library's GitHub repository for release announcements, security advisories, and bug fixes specifically for egulias/emailvalidator.
  3. Use dependency management tools (e.g., Composer for PHP) to check for available updates for egulias/emailvalidator.
  4. When updates are available, especially security-related updates for egulias/emailvalidator, prioritize updating the library to the latest stable version.
  5. After updating, run thorough testing to ensure compatibility and that the update has not introduced any regressions in your application's email validation functionality, specifically focusing on how emailvalidator is used.

• Threats Mitigated:

  • Known Vulnerabilities (including ReDoS) in emailvalidator: Severity: High to Critical. Outdated versions of egulias/emailvalidator are susceptible to known vulnerabilities that are publicly disclosed and can be exploited by attackers. This directly addresses ReDoS vulnerabilities and other potential security flaws within the emailvalidator library itself.

• Impact:

  • Known Vulnerabilities: Impact: High. Keeps the application protected against known vulnerabilities specific to emailvalidator that are fixed in newer versions of the library. This is crucial for maintaining the security of the email validation process provided by the library.

• Currently Implemented:

  • The project uses Composer for dependency management and composer outdated is run manually by developers approximately every month to check for dependency updates, including egulias/emailvalidator.

• Missing Implementation:

  • Automated dependency update checks specifically for egulias/emailvalidator and other security-sensitive libraries are not implemented.
  • There is no formal process for prioritizing and applying security updates specifically for egulias/emailvalidator.
  • Testing after egulias/emailvalidator updates is not consistently performed, focusing on email validation functionality.

Mitigation Strategy: Choose Appropriate Validation Level

• Description:

  1. Review the different validation strategies offered by egulias/emailvalidator (e.g., RFCValidation, NoRFCWarningsValidation, SpoofCheckValidation, DNSCheckValidation).
  2. Understand the trade-offs between strictness, performance, and security for each validation strategy provided by emailvalidator.
  3. Select the validation strategy from emailvalidator that best aligns with your application's security requirements and functional needs.
  4. Configure the emailvalidator instance in your code to use the chosen validation strategy.
  5. Document the chosen validation strategy from emailvalidator and the rationale behind it.

• Threats Mitigated:

  • Bypassing Validation (Loose Validation with emailvalidator): Severity: Medium. Using overly lenient validation options within emailvalidator might allow invalid or malformed email addresses to pass, potentially leading to issues with email delivery, data integrity, or even exploitation if the application logic relies on strict email format.
  • False Positives (Strict Validation with emailvalidator): Severity: Low to Medium (functional impact). Overly strict validation using emailvalidator might reject valid, albeit unusual, email addresses, causing user frustration and potentially lost business.

• Impact:

  • Bypassing Validation: Impact: Medium. Using a more appropriate validation level offered by emailvalidator (e.g., RFCValidation instead of a very basic custom regex or a less strict emailvalidator option) reduces the risk of accepting invalid emails.
  • False Positives: Impact: Medium. Choosing a balanced validation level within emailvalidator minimizes the chances of rejecting valid emails while still maintaining reasonable security.

• Currently Implemented:

  • The application currently uses new RFCValidation() from emailvalidator for email validation in the registration process.

• Missing Implementation:

  • The contact form and profile update processes are still using a basic, less robust custom regex for email validation instead of utilizing emailvalidator with a defined validation strategy.
  • The choice of RFCValidation within emailvalidator is not explicitly documented or justified in the project documentation.

Mitigation Strategy: Enable DNS Checks (with Performance Considerations)

• Description:

  1. If your application requires a higher level of assurance that the email address is deliverable (e.g., for critical communication, account verification), consider enabling DNS checks using DNSCheckValidation from emailvalidator.
  2. Understand that DNS checks within emailvalidator introduce latency and can impact performance.
  3. Implement DNS checks strategically, only where necessary and where the performance impact is acceptable when using emailvalidator.
  4. Consider implementing caching mechanisms to store DNS results temporarily to reduce repeated DNS lookups for the same domain, especially when using DNSCheckValidation.
  5. Alternatively, perform DNS checks asynchronously or in background jobs to minimize impact on user-facing requests when using DNSCheckValidation.
  6. Monitor DNS check performance when using DNSCheckValidation and adjust caching or asynchronous processing as needed.

• Threats Mitigated:

  • Typos and Invalid Domains (Detected by emailvalidator's DNS Checks): Severity: Low to Medium. DNS checks within emailvalidator help catch typos in domain names and ensure that the domain part of the email address actually exists and is configured to receive email, enhancing the validation provided by emailvalidator.
  • Disposable/Temporary Email Addresses (Reduced by emailvalidator's DNS Checks): Severity: Low. While not foolproof, DNS checks in emailvalidator can sometimes help identify disposable email domains, as some of these services might not have properly configured MX records.

• Impact:

  • Typos and Invalid Domains: Impact: Medium. Significantly reduces the acceptance of email addresses with invalid domains when using emailvalidator's DNS check, improving deliverability and data quality.
  • Disposable/Temporary Email Addresses: Impact: Low. Provides a minor level of defense against disposable email addresses through emailvalidator's DNS check.

• Currently Implemented:

  • DNS checks are enabled for email validation during the user registration process using new DNSCheckValidation() from emailvalidator in addition to RFCValidation.

• Missing Implementation:

  • DNS checks are not enabled for email validation in the contact form or profile update processes when using emailvalidator.
  • Caching of DNS results is not implemented, potentially impacting performance under high load when using DNSCheckValidation.
  • Asynchronous DNS checks are not implemented when using DNSCheckValidation.

Mitigation Strategy: Thorough Testing with Diverse Email Addresses (Including emailvalidator Specific Cases)

• Description:

  1. Create a comprehensive test suite for email validation functionality, specifically when using emailvalidator.
  2. Include a wide range of test cases, covering:
     • Valid email addresses according to RFC standards, ensuring emailvalidator correctly validates them.
     • Invalid email addresses according to RFC standards, ensuring emailvalidator correctly rejects them.
     • Edge cases and unusual but valid email address formats, testing emailvalidator's robustness.
     • Internationalized email addresses (if your application needs to support them and emailvalidator version supports it), verifying emailvalidator's internationalization support.
     • Email addresses specifically crafted to test validation boundaries and potential vulnerabilities within emailvalidator (including ReDoS test cases if available and relevant to emailvalidator's regex patterns).
  3. Run the test suite regularly, especially after updating emailvalidator or making changes to how emailvalidator is used.
  4. Automate the test suite as part of your continuous integration/continuous deployment (CI/CD) pipeline, specifically testing the integration with emailvalidator.
  5. Review test results and address any failures or unexpected behavior related to emailvalidator's validation.

• Threats Mitigated:

  • Validation Bypasses (in emailvalidator Usage): Severity: Medium to High. Testing helps identify cases where the application's usage of emailvalidator might incorrectly accept invalid email addresses, potentially due to misconfiguration or misunderstanding of emailvalidator's behavior.
  • ReDoS Vulnerabilities (Detection in emailvalidator): Severity: Medium. Specific ReDoS test cases, relevant to emailvalidator's regex patterns, can help uncover potential ReDoS vulnerabilities within emailvalidator or in how it's used.
  • Functional Errors (in emailvalidator Integration): Severity: Medium. Testing ensures that valid email addresses are correctly accepted and that the validation logic using emailvalidator functions as expected.

• Impact:

  • Validation Bypasses: Impact: High. Significantly reduces the risk of validation bypasses when using emailvalidator by proactively identifying and fixing them through testing.
  • ReDoS Vulnerabilities: Impact: Medium. Increases the chances of detecting ReDoS vulnerabilities related to emailvalidator during development and testing.
  • Functional Errors: Impact: High. Ensures the reliability and correctness of email validation functionality when integrated with emailvalidator.

• Currently Implemented:

  • Basic unit tests exist for the registration process, but they include only a limited number of valid and invalid email address test cases and don't specifically target testing the integration with emailvalidator comprehensively.

• Missing Implementation:

  • A comprehensive test suite with diverse email address test cases, specifically designed to test the application's usage of emailvalidator, is missing.
  • ReDoS specific test cases relevant to emailvalidator are not included.
  • Automated testing of email validation using emailvalidator is not integrated into the CI/CD pipeline.
  • Test coverage for email validation in the contact form and profile update processes using emailvalidator is minimal or non-existent.