Threat: DNS Cache Poisoning
Description: An attacker exploits vulnerabilities in DNS protocol handling or CoreDNS's caching mechanism to inject malicious DNS records into the cache. This can be done by sending crafted DNS responses to CoreDNS that are accepted and cached, overwriting legitimate entries.
Impact: Clients querying CoreDNS are directed to attacker-controlled resources instead of legitimate services. This can lead to phishing attacks, malware distribution, or service disruption.
Affected CoreDNS Component: cache plugin, DNS protocol handling within CoreDNS core.
Risk Severity: High
Mitigation Strategies:
* Enable DNSSEC validation in CoreDNS to verify the authenticity of DNS responses.
* Keep CoreDNS updated to the latest version to patch known caching and DNS protocol vulnerabilities.
* Configure reasonable and short TTL values for cached records to minimize the duration of poisoning.
* Implement monitoring for unusual DNS resolution patterns that might indicate cache poisoning attempts.
Threat: Corefile Configuration Tampering
Description: An attacker gains unauthorized access to the server hosting CoreDNS and modifies the Corefile. They can alter DNS behavior, redirect traffic, disable security plugins, or introduce malicious plugins by editing the configuration file. Impact: Complete control over DNS resolution managed by CoreDNS. Attackers can redirect traffic, cause denial of service, expose internal network information, or introduce backdoors through malicious plugins. Affected CoreDNS Component: Corefile parsing and configuration loading, potentially all plugins depending on the changes. Risk Severity: Critical Mitigation Strategies: * Implement strong access control mechanisms (e.g., file system permissions, RBAC) to restrict who can access and modify the Corefile. * Regularly audit and monitor changes to the Corefile. * Use configuration management tools to enforce configuration integrity and detect unauthorized modifications. * Consider storing the Corefile in a secure location with restricted access.
Description: An attacker introduces malicious CoreDNS plugins or exploits vulnerabilities in existing plugins (especially third-party or custom plugins). Malicious plugins can be designed to alter DNS responses, log sensitive data, or even execute arbitrary code on the server. Vulnerable plugins can be exploited to achieve similar outcomes. Impact: Wide range of impacts depending on the plugin's functionality and the nature of the exploit. This can include data breaches, denial of service, redirection of traffic, or full system compromise if plugin vulnerabilities allow for privilege escalation. Affected CoreDNS Component: Plugin architecture, specific plugins (especially third-party or custom ones). Risk Severity: High (can be Critical depending on plugin and vulnerability) Mitigation Strategies: * Thoroughly vet and audit all plugins before deployment, especially third-party or custom plugins. * Only use plugins from trusted sources and preferably officially maintained plugins. * Keep all plugins and their dependencies updated to the latest versions to patch known vulnerabilities. * Implement security scanning and vulnerability assessments for plugins. * Consider using a minimal set of plugins and disabling unnecessary ones to reduce the attack surface.
Description: An attacker replaces the legitimate CoreDNS binary with a malicious version on the server. This malicious binary can be designed to perform any action, including altering DNS responses, logging data, or providing backdoor access to the system. Impact: Complete compromise of the DNS server. Attackers gain full control over DNS resolution and potentially the entire server, leading to data breaches, denial of service, and further system compromise. Affected CoreDNS Component: CoreDNS executable binary. Risk Severity: Critical Mitigation Strategies: * Implement integrity checks for the CoreDNS binary using checksums or digital signatures to detect unauthorized modifications. * Use secure software distribution channels and verify the integrity of downloaded binaries before deployment. * Restrict access to the server and the directory containing the CoreDNS binary to prevent unauthorized replacement. * Implement file system monitoring to detect unauthorized changes to the CoreDNS binary.
Description: An attacker floods CoreDNS with a massive volume of DNS queries, overwhelming its resources (CPU, memory, network bandwidth). This can be achieved using botnets or by exploiting open resolvers. Impact: DNS resolution becomes slow or unavailable for legitimate clients, disrupting application functionality and potentially impacting dependent services. Affected CoreDNS Component: CoreDNS core, network input/output handling. Risk Severity: High Mitigation Strategies: * Implement rate limiting and request throttling in CoreDNS or using external firewalls/load balancers to limit the number of queries processed from a single source or in total. * Configure resource limits for CoreDNS (e.g., CPU and memory limits in containerized environments) to prevent excessive resource consumption. * Deploy CoreDNS behind load balancers and firewalls to distribute traffic and filter malicious requests. * Monitor CoreDNS resource usage and performance to detect and respond to potential DoS attacks.
Description: Vulnerabilities in CoreDNS plugins, especially those interacting with the operating system or external services, can be exploited to gain elevated privileges on the server running CoreDNS. This could involve code injection, command injection, or other vulnerabilities that allow an attacker to execute arbitrary code with higher privileges. Impact: Full system compromise. An attacker can gain root or administrator privileges on the server, allowing them to access sensitive data, install malware, or perform any other malicious actions. Affected CoreDNS Component: Vulnerable plugins, plugin interaction with the operating system. Risk Severity: Critical Mitigation Strategies: * Apply all plugin security mitigations mentioned previously (vetting, updates, minimal plugins, security scanning). * Run CoreDNS with the least privileges necessary (non-root user, restricted capabilities). * Implement security hardening measures on the server running CoreDNS (e.g., SELinux, AppArmor, kernel hardening) to limit the impact of potential privilege escalation. * Use security sandboxing or containerization to isolate CoreDNS and limit the potential impact of plugin vulnerabilities on the host system.