Skip to content

Latest commit

 

History

History
171 lines (152 loc) · 21.3 KB

mitigations.md

File metadata and controls

171 lines (152 loc) · 21.3 KB

Mitigation Strategies Analysis for postalserver/postal

Mitigation Strategy: Multi-Factor Authentication (MFA) for Admin Access

  • Description:
    1. Explore Postal MFA Options: Investigate if Postal offers built-in MFA or integrations with external MFA providers for the admin interface. Consult Postal's documentation and community resources.
    2. Enable Postal MFA: If MFA is available within Postal, enable it in the admin settings.
    3. Configure MFA Methods in Postal: Choose suitable MFA methods supported by Postal (e.g., TOTP, if available).
    4. Enforce MFA for Postal Admins: Configure Postal to mandate MFA for all administrator logins to the Postal admin panel.
    5. Admin User Guidance: Provide clear instructions to Postal administrators on setting up and using MFA within the Postal system.
  • Threats Mitigated:
    • Account Takeover (High Severity): Unauthorized access to Postal's admin interface due to compromised admin credentials, leading to full control over email infrastructure and data.
  • Impact:
    • Account Takeover: High risk reduction. MFA significantly reduces the risk of admin account takeover by adding an extra layer of security beyond passwords, directly protecting Postal's core management.
  • Currently Implemented: Not currently implemented within Postal's admin access. We rely solely on passwords for Postal admin logins.
  • Missing Implementation: MFA implementation for Postal's admin interface. This needs to be configured within Postal's settings, potentially requiring integration of an MFA plugin or external provider if natively unsupported.

Mitigation Strategy: Enforce Strong Password Policies within Postal

  • Description:
    1. Access Postal Password Settings: Locate password policy configuration options within Postal's admin interface or configuration files.
    2. Configure Postal Password Complexity: Set password complexity requirements directly within Postal's user management settings. This should include:
      • Minimum password length enforced by Postal.
      • Requirement for character types (uppercase, lowercase, numbers, symbols) if configurable in Postal.
    3. Enable Password Expiration in Postal (If Available): If Postal supports password expiration, enable and configure a reasonable expiration period for Postal user accounts.
    4. Communicate Postal Password Policy: Inform all Postal users, especially administrators and organization users, about the enforced password policy within the Postal system.
  • Threats Mitigated:
    • Brute-Force Attacks on Postal Accounts (Medium Severity): Automated attempts to guess passwords for Postal user accounts. Strong passwords enforced by Postal make these attacks harder.
    • Dictionary Attacks on Postal Accounts (Medium Severity): Attacks using common words to guess Postal passwords. Strong Postal password policies mitigate this.
    • Weak Postal Passwords (Low Severity): Users choosing easily guessable passwords for their Postal accounts. Postal policies force stronger passwords.
  • Impact:
    • Brute-Force Attacks: Medium risk reduction. Increases difficulty of brute-forcing Postal accounts.
    • Dictionary Attacks: Medium risk reduction. Makes dictionary attacks against Postal accounts ineffective.
    • Weak Postal Passwords: High risk reduction. Prevents weak passwords for Postal users.
  • Currently Implemented: Partially implemented within Postal. We have a minimum password length, but full complexity and expiration are not enforced through Postal's configuration.
  • Missing Implementation: Full enforcement of password complexity rules and password expiration policies directly within Postal's user account management.

Mitigation Strategy: Principle of Least Privilege for Postal User Roles

  • Description:
    1. Review Postal's RBAC: Thoroughly understand the different user roles and permissions available within Postal's Role-Based Access Control system.
    2. Audit Postal User Roles: Review the roles currently assigned to all users in Postal. Identify any users with overly broad permissions within the Postal context.
    3. Restrict Postal Admin Roles: Limit the number of users with Postal administrator roles to only those strictly necessary for managing the Postal system itself.
    4. Assign Minimal Postal Roles: For all other Postal users, assign the least privileged role that still allows them to perform their required actions within Postal. For example, users only needing to send emails via Postal should not have organization admin roles in Postal.
    5. Regular Postal Role Review: Periodically review and re-evaluate user roles within Postal to ensure they remain aligned with the principle of least privilege as user responsibilities evolve within the Postal system.
  • Threats Mitigated:
    • Privilege Escalation within Postal (Medium to High Severity): Compromise of a lower-privileged Postal account leading to unauthorized actions due to excessive permissions within Postal.
    • Insider Threats within Postal (Low to Medium Severity): Limits potential damage from malicious or negligent actions by authorized Postal users by restricting their access within Postal.
  • Impact:
    • Privilege Escalation: Medium risk reduction. Limits damage from compromised Postal accounts.
    • Insider Threats: Low to Medium risk reduction. Reduces scope of potential insider actions within Postal.
  • Currently Implemented: Partially implemented within Postal. User roles are defined in Postal, but a full audit and strict enforcement of least privilege across all Postal users is needed.
  • Missing Implementation: Comprehensive audit of Postal user roles and permissions, followed by adjustments to enforce least privilege across all Postal accounts and roles.

Mitigation Strategy: Secure Postal API Key Management and Security

  • Description:
    1. Generate Unique Postal API Keys: When creating API keys within Postal for accessing its API, ensure they are unique, sufficiently long, and randomly generated by Postal.
    2. Secure Storage of Postal API Keys: Store Postal API keys securely outside of application code.
      • Use environment variables to inject Postal API keys into applications interacting with Postal.
      • For enhanced security, utilize secrets management systems to store and retrieve Postal API keys.
    3. Postal API Key Rotation: Implement a policy for regular rotation of Postal API keys. Periodically generate new Postal API keys and invalidate older ones within Postal.
    4. Postal API Rate Limiting and Access Controls: Utilize Postal's built-in API rate limiting features to prevent abuse of the Postal API. Explore and implement any available access controls within Postal to restrict API access.
    5. Log and Monitor Postal API Usage: Enable logging of Postal API key usage within Postal and monitor for suspicious activity, such as unauthorized access attempts or unusual API call patterns to Postal.
  • Threats Mitigated:
    • Postal API Key Compromise (High Severity): Exposed or stolen Postal API keys granting unauthorized access to Postal's API, allowing attackers to send emails, access Postal data, or modify Postal configurations.
    • Postal API Abuse (Medium Severity): Misuse of compromised Postal API keys to send spam, phishing emails, or perform DoS attacks through the Postal API.
  • Impact:
    • Postal API Key Compromise: High risk reduction. Secure storage and rotation minimize the risk of Postal API key compromise.
    • Postal API Abuse: Medium risk reduction. Rate limiting and access controls in Postal mitigate API abuse.
  • Currently Implemented: Partially implemented for Postal API keys. Keys are generated and used, but secure storage is basic (environment variables). Postal API key rotation and advanced access controls are not fully implemented.
  • Missing Implementation: Postal API key rotation policy, integration with secrets management for Postal API keys, and more granular access controls for the Postal API beyond basic rate limiting.

Mitigation Strategy: Strict SPF, DKIM, and DMARC Configuration for Postal Sending Domains

  • Description:
    1. Configure SPF for Postal Domains: Create or update SPF records in DNS for your sending domains to authorize Postal's mail servers to send emails on behalf of your domains. Configure this in relation to how Postal sends emails.
    2. Configure DKIM in Postal and DNS: Generate a DKIM key pair within Postal. Configure Postal to use the private DKIM key to sign outgoing emails. Publish the public DKIM key in DNS as a TXT record for your sending domains, as required by Postal.
    3. Configure DMARC for Postal Domains: Create a DMARC record in DNS for your sending domains. Specify how recipient servers should handle emails failing SPF/DKIM checks and where to send DMARC reports, considering emails sent via Postal. Start with p=none and progress to stricter policies as confidence increases with Postal's configuration.
    4. Validate Postal DNS Records: Use online SPF, DKIM, and DMARC testing tools to validate DNS records related to Postal's email sending configuration. Test sending emails via Postal to verify SPF and DKIM authentication.
    5. Monitor DMARC Reports for Postal Sending: Regularly monitor DMARC reports to identify authentication failures, spoofing attempts, or configuration issues related to emails sent through Postal.
  • Threats Mitigated:
    • Email Spoofing via Postal (High Severity): Attackers spoofing emails as originating from your domain when sent through or related to your Postal setup.
    • Email Tampering of Postal Sent Emails (Medium Severity): Ensures integrity of emails sent via Postal using DKIM.
    • Reduced Deliverability of Postal Emails (Medium Severity): Lack of SPF, DKIM, DMARC for domains used with Postal can lead to spam marking and deliverability issues for emails sent via Postal.
  • Impact:
    • Email Spoofing: High risk reduction for emails sent via Postal.
    • Email Tampering: Medium risk reduction for emails sent via Postal.
    • Reduced Email Deliverability: High risk reduction for emails sent via Postal, improving sender reputation for Postal usage.
  • Currently Implemented: Partially implemented for Postal. SPF and DKIM are configured, DMARC is p=none. DMARC report monitoring for Postal sending is not fully automated.
  • Missing Implementation: Transitioning DMARC policy to p=quarantine/p=reject for Postal domains, and automating DMARC report analysis for emails sent via Postal.

Mitigation Strategy: Implement Rate Limiting and Throttling within Postal

  • Description:
    1. Access Postal Rate Limiting Settings: Locate and access Postal's configuration settings for rate limiting and throttling, typically within the admin interface or configuration files.
    2. Configure Postal Rate Limits: Set appropriate rate limits directly within Postal at different levels:
      • Global Postal Rate Limit: Limit total emails sent from the Postal instance per time period, configured in Postal.
      • Organization/User Postal Rate Limits: Set rate limits per organization or user within Postal to prevent abuse by specific Postal accounts.
      • Postal Connection Limits: Limit concurrent connections to Postal's SMTP server to prevent resource exhaustion within Postal.
    3. Implement Postal Throttling: Configure throttling mechanisms within Postal to control sending speed and prevent bursts of emails from Postal.
    4. Monitor Postal Rate Limiting: Monitor Postal's logs and metrics for rate limiting events and adjust configurations within Postal as needed.
    5. Alerting for Postal Rate Limits: Set up alerts within your monitoring system for when Postal rate limits are approached or exceeded, indicating potential abuse or misconfiguration within Postal.
  • Threats Mitigated:
    • Spam Abuse via Postal (High Severity): Prevents Postal from being used to send spam, protecting sender reputation associated with Postal.
    • DoS Attacks on Postal Sending (Medium Severity): Limits impact of DoS attacks targeting Postal's email sending by restricting email transmission rates within Postal.
    • Accidental Over-Sending via Postal (Low Severity): Protects against accidental email floods due to misconfigurations or errors in applications using Postal.
  • Impact:
    • Spam Abuse: High risk reduction. Postal rate limiting prevents spam abuse via Postal.
    • DoS Attacks: Medium risk reduction. Mitigates DoS impact on Postal's sending.
    • Accidental Over-Sending: Low risk reduction. Prevents accidental email floods via Postal.
  • Currently Implemented: Basic global rate limiting in Postal is present. Granular organization/user limits and throttling within Postal are not fully configured.
  • Missing Implementation: Configuration of organization/user-level rate limits within Postal, fine-tuning global Postal rate limits, and implementing throttling mechanisms within Postal.

Mitigation Strategy: Proper Bounce and Complaint Handling in Postal

  • Description:
    1. Configure Postal Bounce Processing: Ensure Postal is correctly configured to process bounce messages. This involves setting up bounce mailboxes and configuring Postal to parse and process bounce notifications.
    2. Implement Postal Complaint Handling (Feedback Loops): Set up feedback loops (FBLs) with major email providers and configure Postal to process complaint reports received through FBLs.
    3. Automate Postal Bounce/Complaint Actions: Configure Postal to automatically take actions based on bounces and complaints, such as:
      • Automatically removing hard-bounced email addresses from sending lists within Postal.
      • Suppressing future sending to complaining email addresses within Postal.
    4. Monitor Postal Bounce/Complaint Rates: Regularly monitor bounce and complaint rates within Postal to identify potential issues with sending practices or list quality.
    5. Investigate High Postal Bounce/Complaint Rates: Investigate and address the root cause of high bounce or complaint rates observed in Postal, such as outdated lists or sending to invalid addresses.
  • Threats Mitigated:
    • Reduced Sender Reputation for Postal (Medium Severity): High bounce and complaint rates from emails sent via Postal negatively impact sender reputation, leading to deliverability issues for legitimate emails sent through Postal.
    • Blacklisting of Postal Sending Infrastructure (Medium to High Severity): Unmanaged bounces and complaints from Postal can lead to blacklisting of Postal's sending IPs or domains by email providers.
    • Inefficient Email Sending via Postal (Low Severity): Sending to invalid or complaining addresses wastes resources and reduces the effectiveness of email campaigns sent via Postal.
  • Impact:
    • Reduced Sender Reputation: Medium risk reduction. Proper bounce/complaint handling in Postal maintains sender reputation for Postal usage.
    • Blacklisting: Medium to High risk reduction. Prevents blacklisting of Postal infrastructure due to poor email hygiene.
    • Inefficient Email Sending: Low risk reduction. Improves efficiency of email sending via Postal.
  • Currently Implemented: Basic bounce processing is configured in Postal, but complaint handling (FBLs) and automated actions based on bounces/complaints are not fully implemented. Monitoring of bounce/complaint rates within Postal is also not fully automated.
  • Missing Implementation: Full configuration of complaint handling (FBLs) within Postal, automation of actions based on bounces and complaints within Postal, and automated monitoring of bounce and complaint rates within Postal.

Mitigation Strategy: Secure Webhooks and Event Handling in Postal

  • Description:
    1. Secure Postal Webhook Endpoints: If using Postal's webhook feature, ensure the webhook endpoints receiving event notifications from Postal are properly secured.
    2. Implement Authentication for Postal Webhooks: Implement authentication mechanisms for webhook endpoints to verify that requests are genuinely originating from Postal. Postal might offer methods like shared secrets or signature verification for webhooks. Utilize these if available.
    3. Validate Postal Webhook Data: Validate and sanitize data received from Postal webhooks to prevent injection vulnerabilities in webhook handlers.
    4. HTTPS for Postal Webhooks: Ensure webhook communication between Postal and your endpoints uses HTTPS to protect data in transit.
    5. Error Handling and Logging for Postal Webhooks: Implement robust error handling and logging for webhook processing to detect and address any issues with webhook delivery or processing from Postal.
  • Threats Mitigated:
    • Unauthorized Access to Webhook Data from Postal (Medium Severity): Unsecured webhook endpoints can allow unauthorized parties to intercept or access sensitive event data sent by Postal via webhooks.
    • Webhook Replay Attacks from Postal (Medium Severity): Without proper authentication, attackers could potentially replay webhook requests from Postal to trigger unintended actions.
    • Injection Vulnerabilities in Webhook Handlers (Medium Severity): If webhook data from Postal is not properly validated, it could lead to injection vulnerabilities in the application processing webhooks.
  • Impact:
    • Unauthorized Access to Webhook Data: Medium risk reduction. Securing webhooks prevents unauthorized data access.
    • Webhook Replay Attacks: Medium risk reduction. Authentication mitigates replay attacks.
    • Injection Vulnerabilities: Medium risk reduction. Data validation prevents injection flaws.
  • Currently Implemented: Webhooks are used, but authentication for webhook endpoints receiving data from Postal is not fully implemented. Data validation and robust error handling for Postal webhooks are also areas for improvement. HTTPS is used.
  • Missing Implementation: Implementation of authentication for webhook endpoints receiving events from Postal (using shared secrets or signature verification if offered by Postal), thorough validation and sanitization of webhook data from Postal, and enhanced error handling and logging for Postal webhook processing.

Mitigation Strategy: Regularly Update Postal and Dependencies

  • Description:
    1. Monitor Postal Releases: Subscribe to Postal's release notes, security advisories, and community channels to stay informed about new versions, security patches, and updates for Postal.
    2. Establish Postal Update Schedule: Create a schedule for regularly updating Postal and its dependencies. Prioritize security updates and patches.
    3. Test Postal Updates: Before applying updates to production, test them in a staging or development environment to ensure compatibility and identify any potential issues.
    4. Apply Postal Updates Promptly: Apply security patches and updates to your Postal instance promptly after testing to address known vulnerabilities.
    5. Update Postal Dependencies: Regularly update the operating system, database, libraries, and other dependencies used by Postal to benefit from security fixes and improvements in those components.
  • Threats Mitigated:
    • Exploitation of Known Postal Vulnerabilities (High Severity): Outdated versions of Postal may contain known security vulnerabilities that attackers can exploit to compromise the Postal system.
    • Exploitation of Dependency Vulnerabilities (Medium to High Severity): Vulnerabilities in Postal's dependencies (OS, database, libraries) can also be exploited to attack the Postal application.
  • Impact:
    • Exploitation of Postal Vulnerabilities: High risk reduction. Regular updates patch known Postal vulnerabilities.
    • Exploitation of Dependency Vulnerabilities: Medium to High risk reduction. Updating dependencies addresses vulnerabilities in underlying components.
  • Currently Implemented: We have a process for updating Postal, but it is not strictly scheduled or as prompt as it should be for security updates. Dependency updates are also performed, but not always in direct coordination with Postal updates.
  • Missing Implementation: Establish a more rigorous and scheduled process for regularly monitoring, testing, and promptly applying updates to Postal and its dependencies, especially security patches.