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attack-surface.md

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Attack Surface Analysis for puppetlabs/puppet

Attack Surface: Compromised Puppet Master

  • Description: An attacker gains full control of the Puppet Master server, allowing them to distribute malicious configurations to all managed nodes.
    • How Puppet Contributes: The Puppet Master is the central authority; its compromise is the single biggest point of failure in a Puppet infrastructure. Puppet's design inherently centralizes control.
    • Example: An attacker exploits a vulnerability in the Puppet Server software to gain root access, then modifies the site manifest to install a backdoor on all managed nodes.
    • Impact: Complete compromise of all managed nodes; data breaches, system disruption, potential lateral movement within the network.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Regularly update Puppet Server: Apply security patches and updates for Puppet Server, its dependencies (Ruby, web server, etc.), and the underlying operating system promptly. This directly addresses vulnerabilities in Puppet.
      • Harden the Puppet Master server: Follow operating system hardening guidelines, disable unnecessary services, and restrict network access using firewalls (host-based and network-based).
      • Implement strong authentication and authorization: Use strong, unique passwords, multi-factor authentication (MFA) where possible, and configure Role-Based Access Control (RBAC) in Puppet Enterprise to limit user privileges. This directly addresses access control to Puppet.
      • Secure communication: Enforce HTTPS with valid, trusted certificates. Regularly review and update SSL/TLS configurations to use strong ciphers and protocols. This secures Puppet's communication channels.
      • Monitor the Puppet Master: Implement robust logging and monitoring to detect suspicious activity, including failed login attempts, unauthorized configuration changes, and unusual resource usage. This monitors Puppet's activity.
      • Use a dedicated, isolated network segment: Place the Puppet Master on a separate, highly restricted network segment with limited inbound and outbound access.
      • Regularly audit Puppet code and infrastructure: Conduct security audits of the Puppet code, infrastructure configuration, and access controls.
      • Implement a robust change management process: Require code reviews and testing before deploying changes to the Puppet Master.

Attack Surface: Supply Chain Attacks via Puppet Modules

  • Description: An attacker compromises a Puppet module (either on the Puppet Forge or a private repository) and injects malicious code that is then executed on managed nodes.
    • How Puppet Contributes: Puppet's reliance on modules for code reusability, and the use of the public Puppet Forge, creates a direct vector for supply chain attacks through Puppet.
    • Example: An attacker publishes a seemingly legitimate module to the Puppet Forge that contains a hidden script to exfiltrate data. Users download and install the module, unknowingly compromising their systems.
    • Impact: Compromise of managed nodes, data breaches, system disruption, depending on the malicious code.
    • Risk Severity: High
    • Mitigation Strategies:
      • Carefully vet modules: Before using a module from the Puppet Forge, review its source code, check its reputation (downloads, ratings, community feedback), and verify the author's identity. This is a direct mitigation for Puppet module usage.
      • Use a private module repository: For sensitive environments, consider using a private module repository where you can control the modules that are available. This controls the source of Puppet code.
      • Pin module versions: Specify exact versions of modules in your Puppetfile or metadata.json to prevent automatic updates to potentially compromised versions. This directly manages Puppet module dependencies.
      • Implement code signing: Use code signing to verify the integrity and authenticity of modules. This verifies the origin of Puppet code.
      • Regularly scan modules for vulnerabilities: Use vulnerability scanning tools to identify known vulnerabilities in the modules you are using.
      • Contribute back to the community: If you find vulnerabilities or security issues in modules, report them to the module author and the Puppet community.

Attack Surface: Man-in-the-Middle (MitM) Attacks on Agent-Master Communication

  • Description: An attacker intercepts and modifies the communication between Puppet agents and the master, injecting malicious configurations or stealing data.
    • How Puppet Contributes: Puppet's agent-master communication model, as implemented by Puppet, is susceptible to MitM attacks if not properly secured using Puppet's built-in mechanisms.
    • Example: An attacker on the same network as a Puppet agent uses ARP spoofing to intercept traffic between the agent and the master. The attacker then modifies the catalog sent to the agent to install malware.
    • Impact: Compromise of the targeted agent, potential data breaches, system disruption.
    • Risk Severity: High
    • Mitigation Strategies:
      • Enforce HTTPS with valid, trusted certificates: Ensure that all communication between agents and the master uses HTTPS with properly configured certificates. Do not disable certificate verification. This is a direct configuration of Puppet's communication.
      • Use a trusted Certificate Authority (CA): Use a reputable CA to issue certificates for Puppet agents and the master. Avoid self-signed certificates in production. This leverages Puppet's certificate infrastructure.
      • Regularly rotate certificates: Implement a process for regularly rotating certificates to minimize the impact of a compromised certificate. This is part of Puppet's certificate management.
      • Network segmentation: Isolate Puppet agents and the master on separate network segments to limit the exposure to MitM attacks.
      • Monitor network traffic: Monitor network traffic for suspicious activity, such as unexpected connections or unusual data transfers.

Attack Surface: Insecure Handling of Secrets in Puppet Code

  • Description: Sensitive information (passwords, API keys, etc.) is stored directly in Puppet code or manifests, making it vulnerable to exposure.
    • How Puppet Contributes: Puppet code often needs to manage secrets, and how this is done within the Puppet code itself is the direct source of the risk.
    • Example: A developer hardcodes a database password in a Puppet manifest. If the Puppet code is compromised (e.g., through a compromised VCS), the password is exposed.
    • Impact: Exposure of sensitive information, leading to potential data breaches, unauthorized access to systems, and other security incidents.
    • Risk Severity: High
    • Mitigation Strategies:
      • Use a dedicated secret management solution: Integrate Puppet with a secret management solution like HashiCorp Vault, AWS Secrets Manager, Azure Key Vault, or CyberArk Conjur. This is about how Puppet interacts with secrets.
      • Use Hiera-eyaml: If using Hiera (Puppet's data lookup system), use Hiera-eyaml to encrypt sensitive data within Hiera data files. Ensure the encryption keys are securely managed. This is a direct Puppet-specific solution.
      • Avoid storing secrets in version control: Never commit secrets to your version control system (e.g., Git).
      • Use environment variables (with caution): In some cases, environment variables can be used to pass secrets to Puppet, but this should be done with caution and only when other solutions are not feasible. Ensure the environment variables are properly secured.
      • Educate developers: Train developers on secure coding practices and the importance of proper secret management.

Attack Surface: Overly Permissive exec Resources

  • Description: exec resources in Puppet are used to execute arbitrary commands. Poorly configured exec resources can be exploited for command injection.
    • How Puppet Contributes: The exec resource is a built-in and potentially dangerous feature of Puppet itself. Its misuse is a direct Puppet-related risk.
    • Example: An exec resource is used to run a script that takes user input as an argument. If the input is not properly sanitized, an attacker could inject malicious commands. exec { 'dangerous_command': command => "/bin/sh -c \"myscript.sh ${user_input}\"", }
    • Impact: Command injection, potentially leading to arbitrary code execution, system compromise, and data breaches.
    • Risk Severity: High
    • Mitigation Strategies:
      • Avoid exec resources whenever possible: Use built-in Puppet resource types or custom types/providers instead of exec whenever possible. This is a direct recommendation about Puppet code.
      • Use the onlyif, unless, creates parameters: These parameters, part of the exec resource definition in Puppet, can help prevent unnecessary execution and limit impact.
      • Sanitize input: If you must use exec with user-supplied input, carefully sanitize the input to prevent command injection. Use whitelisting instead of blacklisting whenever possible.
      • Use fully qualified paths: Specify the full path to the command being executed to prevent attackers from substituting malicious commands.
      • Limit the privileges of the user running the command: If possible, run the exec resource as a non-privileged user. This can be configured within the Puppet exec resource.
      • Log the output of exec resources: Log the output of exec resources to help with debugging and auditing.