mitigations.md

Mitigation Strategies Analysis for coredns/coredns

Mitigation Strategy: Regularly Update CoreDNS

• Description:

  1. Establish CoreDNS Version Tracking: Document the current CoreDNS version in use and subscribe to CoreDNS security mailing lists or GitHub release notifications to stay informed about new releases and security advisories.
  2. Regularly Check for CoreDNS Updates: Set a schedule (e.g., monthly) to specifically check for new CoreDNS releases on the official CoreDNS website or GitHub repository.
  3. Test CoreDNS Updates in Staging: Before production deployment, deploy the new CoreDNS version to a staging environment that mirrors the production CoreDNS setup. Conduct testing focused on CoreDNS functionality and stability.
  4. Apply CoreDNS Updates to Production: Schedule a maintenance window to update CoreDNS in the production environment, following established CoreDNS-specific deployment procedures.
  5. Verify CoreDNS Update Success: After updating, verify the CoreDNS version in production and specifically monitor CoreDNS logs and metrics for any issues post-update.

• Threats Mitigated:

  • Exploitation of Known CoreDNS Vulnerabilities (High Severity): Outdated CoreDNS software is vulnerable to publicly known exploits targeting CoreDNS. Regular updates patch these CoreDNS-specific vulnerabilities.

• Impact:

  • Exploitation of Known CoreDNS Vulnerabilities: High Risk Reduction

• Currently Implemented: Partially Implemented

  • We have a general dependency update process, but not a dedicated, scheduled process for CoreDNS updates. We are using CoreDNS version 1.8.0.

• Missing Implementation:

  • Need a dedicated schedule for CoreDNS update checks and integration of CoreDNS version tracking into our dependency management. Upgrade to the latest stable CoreDNS version (e.g., 1.11.x).

Mitigation Strategy: Secure CoreDNS Configuration (Corefile Hardening)

• Description:

  1. In-depth Corefile Review: Carefully examine the Corefile configuration, understanding each CoreDNS plugin and its specific configuration parameters.
  2. Disable Unnecessary CoreDNS Plugins: Remove or comment out any CoreDNS plugins in the Corefile that are not strictly required for your application's DNS resolution needs. Start with a minimal Corefile and add plugins only when necessary.
  3. CoreDNS Plugin Least Privilege: Configure enabled CoreDNS plugins with the minimum necessary permissions and access levels within the Corefile. For example, restrict access paths for the file plugin in the Corefile.
  4. Harden CoreDNS Plugin Configurations: For each enabled CoreDNS plugin in the Corefile, review its specific security-related configuration options and apply hardening measures. For example, for the forward plugin, ensure forwarding only to trusted resolvers specified in the Corefile.
  5. Regular Corefile Audits: Periodically review the Corefile to ensure it remains hardened, aligned with security best practices for CoreDNS configurations, and meets current application DNS requirements.

• Threats Mitigated:

  • CoreDNS Misconfiguration Exploitation (Medium Severity): Default or overly permissive Corefile configurations can expose unintended CoreDNS functionalities or vulnerabilities.
  • CoreDNS Plugin-Specific Vulnerabilities (Medium to High Severity): Unnecessary CoreDNS plugins in the Corefile increase the attack surface and potential for plugin-specific vulnerabilities within CoreDNS.

• Impact:

  • CoreDNS Misconfiguration Exploitation: Medium Risk Reduction
  • CoreDNS Plugin-Specific Vulnerabilities: Medium Risk Reduction

• Currently Implemented: Partially Implemented

  • We use a custom Corefile, but a recent security-focused review for CoreDNS hardening is missing. Plugin selection in the Corefile was based on initial requirements, not a recent security audit.

• Missing Implementation:

  • Conduct a dedicated security audit of the Corefile, focusing on disabling unnecessary CoreDNS plugins and hardening configurations of enabled plugins within the Corefile. Document the security rationale behind each plugin and configuration setting in the Corefile.

Mitigation Strategy: Implement CoreDNS Rate Limiting and Resource Quotas

• Description:

  1. Choose CoreDNS Rate Limiting Plugin: Select a suitable CoreDNS rate limiting plugin for the Corefile, such as the built-in limit plugin. Evaluate if external solutions are needed for more advanced CoreDNS rate limiting features.
  2. Configure CoreDNS Rate Limits in Corefile: Define appropriate rate limits within the Corefile based on expected legitimate DNS traffic patterns and CoreDNS resource capacity. Start with conservative limits in the Corefile and adjust based on monitoring and testing of CoreDNS performance. Configure limits per client IP, query type, or other relevant criteria within the Corefile.
  3. Set CoreDNS Resource Quotas (if applicable): If running CoreDNS in containers, define resource requests and limits (CPU, memory) specifically for the CoreDNS container to prevent resource exhaustion of the CoreDNS service.
  4. Monitor CoreDNS Rate Limiting Effectiveness: Monitor CoreDNS logs and metrics to ensure rate limiting configured in the Corefile is functioning as expected and effectively mitigating DoS attempts against CoreDNS without impacting legitimate DNS traffic.

• Threats Mitigated:

  • Denial of Service (DoS) Attacks Targeting CoreDNS (High Severity): Uncontrolled request rates can overwhelm CoreDNS, leading to CoreDNS service unavailability.

• Impact:

  • Denial of Service (DoS) Attacks Targeting CoreDNS: High Risk Reduction

• Currently Implemented: Not Implemented

  • We do not currently have any rate limiting configured within CoreDNS or resource quotas specifically for CoreDNS.

• Missing Implementation:

  • Implement rate limiting using the limit plugin in the Corefile. Define appropriate rate limits in the Corefile based on traffic analysis and CoreDNS performance testing. Configure resource quotas in our container orchestration system specifically for CoreDNS deployments.

Mitigation Strategy: Enable and Properly Configure CoreDNS DNSSEC

• Description:

  1. Determine CoreDNS DNSSEC Requirement: Assess if your application relies on authoritative DNS zones served by CoreDNS and if DNSSEC within CoreDNS is necessary for ensuring data integrity and authenticity of DNS responses from CoreDNS.
  2. Enable CoreDNS DNSSEC Plugin in Corefile: Enable the dnssec plugin in the Corefile to activate DNSSEC functionality within CoreDNS.
  3. Configure CoreDNS DNSSEC Signing: Configure DNSSEC signing parameters within CoreDNS, including key generation, key management, and signing policies. This typically involves integrating CoreDNS with a key management system or using secure key storage for CoreDNS DNSSEC keys.
  4. Publish CoreDNS DNSSEC Records: Ensure the necessary DNSSEC records (e.g., DS, DNSKEY) generated by CoreDNS are published in the parent zone to establish the chain of trust for DNSSEC validation of CoreDNS responses.
  5. Validate CoreDNS DNSSEC Configuration: Use DNSSEC validation tools to verify that DNSSEC is correctly configured within CoreDNS and that DNS responses from CoreDNS are being signed and validated properly.
  6. Monitor CoreDNS DNSSEC Health: Regularly monitor the health of CoreDNS DNSSEC signing and validation processes, checking for errors or failures in CoreDNS DNSSEC operations.

• Threats Mitigated:

  • DNS Spoofing/Cache Poisoning of CoreDNS Responses (High Severity): Attackers can manipulate DNS responses from CoreDNS to redirect traffic or intercept data. CoreDNS DNSSEC prevents this by ensuring DNS data integrity from CoreDNS.

• Impact:

  • DNS Spoofing/Cache Poisoning of CoreDNS Responses: High Risk Reduction (for authoritative zones served by CoreDNS)

• Currently Implemented: Not Implemented

  • We are not currently using DNSSEC for our authoritative zones served by CoreDNS.

• Missing Implementation:

  • Implement DNSSEC for our authoritative zones served by CoreDNS. This involves key generation for CoreDNS DNSSEC, configuration of the dnssec plugin in the Corefile, and publishing DNSSEC records in the parent zone for CoreDNS. Requires careful planning and execution specific to CoreDNS DNSSEC setup.

Mitigation Strategy: Sanitize and Secure CoreDNS Logs

• Description:

  1. Review CoreDNS Logging Configuration: Examine the CoreDNS logging configuration in the Corefile (e.g., using the log plugin). Identify any potentially sensitive information being logged by CoreDNS (e.g., full query parameters, client IPs if not necessary in CoreDNS logs).
  2. Minimize Sensitive CoreDNS Logging: Adjust CoreDNS logging levels and formats in the Corefile to avoid logging sensitive data unnecessarily in CoreDNS logs. Consider anonymizing or masking sensitive information if logging is required in CoreDNS logs.
  3. Implement CoreDNS Log Rotation and Retention: Configure log rotation specifically for CoreDNS logs to prevent them from consuming excessive disk space. Implement a log retention policy for CoreDNS logs based on security and compliance requirements.
  4. Secure CoreDNS Log Storage and Access: Store CoreDNS logs in a secure location with restricted access. Use appropriate access control mechanisms to ensure only authorized personnel can access CoreDNS logs. Consider using centralized logging solutions with security features for CoreDNS logs.

• Threats Mitigated:

  • Information Disclosure via CoreDNS Logs (Medium Severity): CoreDNS logs can inadvertently expose sensitive information if not properly sanitized.
  • CoreDNS Log Tampering/Manipulation (Medium Severity): If CoreDNS logs are not securely stored and accessed, attackers could tamper with CoreDNS logs to cover their tracks or manipulate evidence related to CoreDNS activity.

• Impact:

  • Information Disclosure via CoreDNS Logs: Medium Risk Reduction
  • CoreDNS Log Tampering/Manipulation: Medium Risk Reduction

• Currently Implemented: Partially Implemented

  • We have basic CoreDNS logging enabled, but haven't reviewed it for sensitive data exposure or implemented robust log security measures specifically for CoreDNS logs.

• Missing Implementation:

  • Review and sanitize the CoreDNS logging configuration in the Corefile. Implement log rotation, retention policies, and secure log storage with access controls specifically for CoreDNS logs.

Mitigation Strategy: Carefully Vet and Secure CoreDNS Plugins

• Description:

  1. CoreDNS Plugin Inventory: Create an inventory of all CoreDNS plugins currently in use in the Corefile.
  2. CoreDNS Plugin Source Verification: For each CoreDNS plugin, verify its source. Prefer plugins from the official CoreDNS repository or reputable and well-maintained sources for CoreDNS plugins.
  3. Security Audits of CoreDNS Plugins: If using third-party or custom CoreDNS plugins, conduct security audits or code reviews to identify potential vulnerabilities within these CoreDNS plugins.
  4. CoreDNS Plugin Updates: Keep all CoreDNS plugins updated to their latest versions to patch any known vulnerabilities in CoreDNS plugins. Subscribe to plugin-specific security advisories if available for CoreDNS plugins.
  5. Minimize CoreDNS Plugin Usage: Adhere to the principle of least privilege and only use CoreDNS plugins that are strictly necessary for your application's DNS resolution needs as configured in the Corefile.

• Threats Mitigated:

  • CoreDNS Plugin Vulnerabilities (Medium to High Severity): Vulnerabilities in CoreDNS plugins can be exploited to compromise CoreDNS or the underlying system.
  • CoreDNS Plugin Supply Chain Risks (Medium Severity): Using CoreDNS plugins from untrusted sources introduces supply chain risks specifically related to CoreDNS.

• Impact:

  • CoreDNS Plugin Vulnerabilities: Medium to High Risk Reduction
  • CoreDNS Plugin Supply Chain Risks: Medium Risk Reduction

• Currently Implemented: Partially Implemented

  • We primarily use plugins from the official CoreDNS repository, but haven't formally vetted them for security vulnerabilities or established a dedicated plugin update process for CoreDNS plugins.

• Missing Implementation:

  • Formally vet all used CoreDNS plugins for security. Establish a process for tracking CoreDNS plugin versions and applying updates. Document the source and rationale for each CoreDNS plugin used in the Corefile.

Mitigation Strategy: Implement Monitoring and Alerting for CoreDNS

• Description:

  1. Define Key CoreDNS Metrics: Identify key metrics to monitor specifically for CoreDNS, such as CoreDNS query rate, CoreDNS error rate, CoreDNS latency, CoreDNS CPU/memory utilization, and CoreDNS DNSSEC validation failures.
  2. Set up CoreDNS Monitoring Tools: Integrate CoreDNS with monitoring tools (e.g., Prometheus, Grafana, ELK stack) to collect and visualize CoreDNS metrics and logs. Ensure monitoring is specifically configured to capture CoreDNS data.
  3. Configure CoreDNS Alerts: Define alerts for abnormal CoreDNS behavior or security-related events specific to CoreDNS, such as high CoreDNS error rates, sudden changes in CoreDNS query patterns, CoreDNS resource exhaustion, or security-related log messages from CoreDNS.
  4. Establish CoreDNS Alert Response Procedures: Define procedures for responding to CoreDNS-specific alerts, including investigation steps, escalation paths, and mitigation actions for CoreDNS issues.
  5. Regularly Review CoreDNS Monitoring and Alerting: Periodically review CoreDNS monitoring dashboards and alerting rules to ensure they are effective and aligned with current security and operational needs for CoreDNS.

• Threats Mitigated:

  • Delayed CoreDNS Incident Detection (Medium to High Severity): Without dedicated CoreDNS monitoring and alerting, security incidents or performance issues within CoreDNS may go undetected for extended periods.
  • CoreDNS Service Disruption (Medium to High Severity): Monitoring helps detect and prevent service disruptions specifically related to CoreDNS caused by attacks or misconfigurations affecting CoreDNS.

• Impact:

  • Delayed CoreDNS Incident Detection: High Risk Reduction
  • CoreDNS Service Disruption: Medium Risk Reduction

• Currently Implemented: Partially Implemented

  • We have basic monitoring of CoreDNS resource utilization, but lack detailed DNS-specific metrics and security-related alerts specifically for CoreDNS.

• Missing Implementation:

  • Implement comprehensive monitoring specifically for CoreDNS, including DNS-specific metrics and security-related events from CoreDNS. Configure alerts for anomalies and security incidents related to CoreDNS and establish incident response procedures for CoreDNS issues.