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Mitigation Strategies Analysis for egulias/emailvalidator

Mitigation Strategy: Choose Appropriate Validation Level

  • Description:

    1. Review Documentation: Thoroughly read the egulias/email-validator documentation on GitHub to understand the different validation levels (RFCValidation, NoRFCWarningsValidation, DNSCheckValidation, MultipleValidationWithAnd, SpoofCheckValidation, etc.). Pay close attention to the specific rules enforced by each level.
    2. Assess Needs: Determine the specific requirements of your application. Do you need strict RFC compliance? Is DNS validation essential, or can you rely on format validation alone? Consider the user experience – overly strict validation can be frustrating.
    3. Select Level: Choose the validation level that best balances security and usability. Start with RFCValidation or NoRFCWarningsValidation as a good default. If DNS validation is required, proceed with caution (see Mitigation #3). If using MultipleValidationWithAnd, ensure all validations are necessary.
    4. Document Choice: Clearly document the chosen validation level and the rationale behind it in your project's documentation (e.g., in a README, security guidelines, or code comments).
    5. Regular Review: Periodically review the chosen validation level to ensure it still meets the evolving needs of the application and the threat landscape.

  • Threats Mitigated:

    • Invalid Email Format Injection (High Severity): Reduces the risk of accepting email addresses that violate RFC specifications, which could be used for various injection attacks. The correct level is key here.
    • Denial of Service (DoS) via DNS (Medium Severity): By avoiding unnecessary DNSCheckValidation, you reduce the risk of DoS attacks targeting your DNS resolution.
    • User Frustration (Low Severity): Choosing an appropriately permissive level (while still being secure) prevents valid but unusual email addresses from being rejected.

  • Impact:

    • Invalid Email Format Injection: Significantly reduces the risk. The library enforces RFC compliance at the chosen level.
    • DoS via DNS: Reduces the risk by limiting the use of DNS lookups.
    • User Frustration: Minimizes user frustration by accepting a wider range of valid email addresses.

  • Currently Implemented: RFCValidation is currently used in the user registration module (/app/Controllers/Auth/RegisterController.php).

  • Missing Implementation: The contact form (/app/Controllers/ContactController.php) currently uses no email validation library. This needs to be updated to use RFCValidation.

Mitigation Strategy: Handle DNS Lookup Failures and Timeouts (if using DNSCheckValidation)

  • Description:

    1. Implement Timeouts: Set a strict timeout for DNS lookups (e.g., 2-3 seconds) when using DNSCheckValidation. This prevents slow DNS servers from blocking your application. This is done when calling the library's DNSCheckValidation.
    2. Handle Exceptions: Wrap the DNSCheckValidation call in a try-catch block to handle potential exceptions (e.g., Egulias\EmailValidator\Exception\NoDNSRecord). This is specific to how you use the library.
    3. Fallback Mechanism: Implement a fallback mechanism. If the DNS lookup fails or times out:
      • Option 1 (Preferred): Log the failure and fall back to a less strict validation level (e.g., RFCValidation). This involves switching to a different validation object from the library.
      • Option 2: Display a user-friendly error message indicating a temporary problem and asking the user to try again later. Do not simply reject the email address.
    4. Retry with Backoff: Consider implementing a retry mechanism with exponential backoff. If the first DNS lookup fails, wait a short period (e.g., 1 second), then retry. If it fails again, wait longer (e.g., 2 seconds), and so on. Limit the number of retries. This logic surrounds the use of the library.
    5. Log Failures: Log all DNS lookup failures and timeouts, including the email address, timestamp, and error details. This helps with debugging and identifying potential attacks.
    6. Monitor: Use application performance monitoring to track DNS resolution times and failure rates.

  • Threats Mitigated:

    • Denial of Service (DoS) via DNS (Medium Severity): Prevents attackers from using slow or malicious DNS servers to make your application unresponsive. Directly related to how you handle the results of DNSCheckValidation.
    • Information Leakage (Low Severity): Reduces the risk of leaking information about your users (or your server's probing) to external DNS servers.

  • Impact:

    • DoS via DNS: Significantly reduces the risk by preventing long delays and handling failures gracefully.
    • Information Leakage: Minimizes the impact by limiting the number of DNS lookups.

  • Currently Implemented: No DNS validation is currently used.

  • Missing Implementation: If DNSCheckValidation is ever implemented, all the steps above must be followed.

Mitigation Strategy: Address Spoofing Limitations (if using SpoofCheckValidation)

  • Description:

    1. Use SpoofCheckValidation: If appropriate for your application, use the SpoofCheckValidation to detect visually similar characters. This is a direct use of the library's functionality.
    2. Combine with Other Measures: While not directly related to the library itself, if you are processing incoming email, consider combining SpoofCheckValidation with sender authentication technologies.
    3. Regular Updates: Stay informed about new spoofing techniques.

  • Threats Mitigated:

    • Phishing Attacks (Medium Severity): Helps detect some phishing attempts that rely on visually similar email addresses. This is a direct result of using SpoofCheckValidation.
    • Account Takeover (High Severity): By reducing phishing success, it indirectly helps prevent account takeover.

  • Impact:

    • Phishing Attacks: Reduces the risk, but it's not a foolproof solution.
    • Account Takeover: Provides a small reduction in risk.

  • Currently Implemented: SpoofCheckValidation is not currently used.

  • Missing Implementation: Consider adding SpoofCheckValidation to the user registration process.

Mitigation Strategy: Handle IDNs and Unicode (with SpoofCheckValidation and Validation Level Considerations)

  • Description:

    1. Understand IDN Representations: Be aware of how email-validator handles IDNs, particularly the A-label (Punycode) representation it uses internally.
    2. Homograph Awareness: Be aware of potential homograph attacks, and use SpoofCheckValidation to help mitigate them. This is a direct interaction with the library.
    3. Validation Level: Ensure the chosen validation level correctly handles IDNs. RFCValidation and others should support them, but it's crucial to confirm.

  • Threats Mitigated:

    • Homograph Attacks (Medium Severity): SpoofCheckValidation directly helps mitigate this.
    • Data Inconsistency (Low Severity): Understanding how the library handles IDNs prevents inconsistencies.

  • Impact:

    • Homograph Attacks: Reduces the risk, especially when SpoofCheckValidation is used.
    • Data Inconsistency: Prevents issues by understanding the library's IDN handling.

  • Currently Implemented: The application does not explicitly use SpoofCheckValidation.

  • Missing Implementation: The application should consider using SpoofCheckValidation to improve IDN-related security.