Threat: Exposed Caddy Admin API
Description: An attacker gains unauthorized access to the Caddy Admin API (if enabled and not properly secured). This allows them to modify Caddy's configuration, restart the server, deploy malicious configurations, or potentially exploit vulnerabilities within the API itself to gain further control. Impact: Full server compromise, complete service disruption, data manipulation, information disclosure, potential for lateral movement within the network if Caddy has access to other systems. Caddy Component Affected: Admin API Module, HTTP Handler, Core Configuration Loading. Risk Severity: Critical Mitigation Strategies: * Disable the Admin API in production environments unless absolutely necessary. * If required, implement strong authentication and authorization for the Admin API (e.g., API keys, mutual TLS). * Restrict access to the Admin API to trusted networks or IP addresses using firewall rules or access control lists.
Description: An attacker gains unauthorized read or write access to Caddy's configuration files (Caddyfile, JSON configuration, TLS certificates) due to weak file permissions on the server. This allows them to modify the Caddy configuration to inject backdoors, redirect traffic, steal TLS private keys, or cause denial of service. Impact: Server compromise, information disclosure (TLS private keys, configuration details), service disruption, manipulation of served content, potential for man-in-the-middle attacks if TLS keys are stolen. Caddy Component Affected: File System Access, Configuration Loading, TLS Certificate Management. Risk Severity: High Mitigation Strategies: * Ensure strict file permissions on all Caddy configuration files and TLS certificate storage directories. * The Caddy process user should be the only user with read and write access to these files. * Administrators should have read access only when necessary for maintenance. * Regularly audit file permissions to ensure they remain secure.
Description: An attacker exploits known security vulnerabilities present in the Go standard library or third-party libraries that Caddy depends upon. These vulnerabilities could range from memory corruption issues to remote code execution flaws, potentially allowing an attacker to compromise the Caddy process and the underlying server. Impact: Potentially critical vulnerabilities like remote code execution, privilege escalation, denial of service, information disclosure, depending on the specific vulnerability in the dependency. Caddy Component Affected: Core Caddy Binary, Go Standard Library, Third-party Libraries used by Caddy. Risk Severity: High to Critical (depending on the specific vulnerability) Mitigation Strategies: * Keep Caddy updated to the latest version. Caddy updates often include updates to its dependencies, patching known vulnerabilities. * Monitor security advisories for Go and the libraries Caddy uses. * Consider using vulnerability scanning tools to identify known vulnerabilities in Caddy's dependencies.
Threat: Plugin Vulnerabilities
Description: An attacker exploits security vulnerabilities within Caddy plugins, especially those from third-party or community sources. These vulnerabilities could be in the plugin's code itself or in its dependencies, potentially leading to remote code execution, denial of service, or information disclosure within the context of Caddy. Impact: Varies depending on the plugin and vulnerability, but can include remote code execution within the Caddy process, denial of service, information disclosure, or privilege escalation within the Caddy context, potentially impacting other plugins or core Caddy functionality. Caddy Component Affected: Caddy Plugin Architecture, Specific Plugin Modules, Plugin Dependencies. Risk Severity: High to Critical (depending on the plugin and vulnerability) Mitigation Strategies: * Exercise caution when using third-party plugins. Only use plugins from trusted and reputable sources. * If possible, review the source code of plugins before installation, especially for community-developed plugins. * Keep all plugins updated to their latest versions. * Monitor security advisories related to Caddy plugins. * Apply the principle of least privilege to plugin permissions and capabilities.
Description: An attacker compromises the Caddy build or distribution pipeline, or plugin repositories, injecting malicious code into Caddy binaries or plugins offered for download. Users downloading these compromised components unknowingly install malware or backdoors, leading to server compromise. Impact: Full server compromise, data breach, malware distribution, backdoors allowing persistent access, depending on the nature of the malicious code injected. This can have widespread impact if many users download compromised versions. Caddy Component Affected: Caddy Distribution Channels (official website, GitHub releases), Plugin Repositories, Build Process, Update Mechanisms. Risk Severity: Critical Mitigation Strategies: * Always download Caddy binaries and plugins from official and trusted sources only (e.g., official Caddy website, official GitHub releases). * Verify the integrity of downloaded binaries using checksums (SHA256) or digital signatures provided by the Caddy project. * Implement software supply chain security best practices within your own infrastructure to prevent internal compromise that could lead to serving malicious versions.
Description: An attacker exploits dependency confusion in the context of Caddy plugins. If plugins rely on dependencies that are not explicitly specified as private or internal, an attacker could upload malicious packages with the same names to public package repositories (like Go modules proxy). When Caddy or plugin installation processes attempt to resolve dependencies, they might inadvertently download and use the attacker's malicious packages instead of the intended legitimate ones. Impact: Potentially remote code execution during plugin installation or runtime, supply chain compromise affecting specific plugins, depending on the malicious package's payload. This can lead to server compromise or malicious plugin functionality. Caddy Component Affected: Plugin Installation Mechanisms, Dependency Management within Plugins, Build Process for Plugins. Risk Severity: High Mitigation Strategies: * When developing or using Caddy plugins, ensure proper dependency management practices are in place. * Use private Go module proxies or vendoring to isolate plugin dependencies and prevent reliance on public repositories for internal dependencies. * Carefully review and verify all plugin dependencies and their sources. * Implement security scanning of plugin dependencies to detect known vulnerabilities or suspicious packages.