mitigations.md

Mitigation Strategies Analysis for filosottile/mkcert

Mitigation Strategy: Restrict Access to the Root CA Private Key

• Description:
  1. Identify the Root CA Key Location: Determine the default location where mkcert stores the Root CA and private key (typically within the user's home directory, e.g., ~/.local/share/mkcert on Linux, ~/Library/Application Support/mkcert on macOS, %LOCALAPPDATA%\mkcert on Windows).
  2. Apply File System Permissions: Use operating system-level file permissions to restrict read and write access to the Root CA directory and its contents.
     • On Linux/macOS: Use chmod 700 ~/.local/share/mkcert (or equivalent path) to grant read, write, and execute permissions only to the owner (the developer user).
     • On Windows: Use NTFS permissions to grant "Full Control" only to the developer user account and remove permissions for other users and groups.
  3. Avoid Sharing the Key: Explicitly instruct developers to never share the Root CA private key through any means (email, chat, version control, shared drives, etc.).
• List of Threats Mitigated:
  • Threat: Root CA Private Key Compromise (High Severity) - If the private key is compromised, attackers can issue trusted certificates for any domain, enabling man-in-the-middle attacks, phishing, and code signing attacks.
• Impact: High Risk Reduction - Significantly reduces the risk of unauthorized access and misuse of the Root CA private key.
• Currently Implemented: Partially Implemented - File system permissions are generally left at default by developers, but awareness is raised during onboarding.
• Missing Implementation: Enforce file system permission checks via automated scripts during developer environment setup. Lack of automated checks to detect accidental sharing of the key.

Mitigation Strategy: Principle of Least Privilege for Certificate Generation

• Description:
  1. Identify Developers Requiring mkcert: Determine which developers genuinely need to generate local HTTPS certificates for their development tasks.
  2. Restrict mkcert Installation: Only install mkcert on the machines of developers who have a documented need for it. Avoid a blanket installation across all development machines.
  3. Control Installation Process: Implement a controlled process for mkcert installation, potentially requiring approval or using a centralized software deployment system.
  4. Regularly Review Access: Periodically review the list of developers with mkcert installed and revoke access for those who no longer require it (e.g., developers changing roles or projects).
• List of Threats Mitigated:
  • Threat: Increased Attack Surface (Medium Severity) - Wider distribution of mkcert increases the number of potential endpoints where the Root CA private key could be vulnerable if a developer machine is compromised.
  • Threat: Accidental Misuse (Low Severity) - Reduces the chance of developers unintentionally using mkcert for purposes outside of local development if they don't have it installed.
• Impact: Medium Risk Reduction - Reduces the overall attack surface and potential for misuse by limiting the distribution of mkcert.
• Currently Implemented: Partially Implemented - Onboarding documentation recommends installing mkcert only when needed, but no strict enforcement.
• Missing Implementation: Implement a software inventory system to track mkcert installations and enforce an approval process for new installations.

Mitigation Strategy: Short Certificate Validity Periods

• Description:
  1. Script Certificate Generation: Create scripts or wrappers around mkcert to automate certificate generation.
  2. Implement Validity Period Logic: Modify these scripts to generate certificates with shorter validity periods than the default (e.g., 30 days, 90 days). While mkcert doesn't directly support validity period flags, you can achieve this by scripting certificate regeneration.
  3. Automate Certificate Renewal Reminders: Implement reminders or automated processes to prompt developers to regenerate certificates before they expire.
  4. Document Renewal Process: Clearly document the certificate renewal process for developers.
• List of Threats Mitigated:
  • Threat: Prolonged Exposure of Compromised Certificate (Medium Severity) - If a certificate is compromised (e.g., through a developer machine compromise), shorter validity periods limit the time window during which the compromised certificate can be misused.
• Impact: Medium Risk Reduction - Reduces the impact of a certificate compromise by limiting its lifespan.
• Currently Implemented: No Implementation - Certificates are generated with default long validity periods.
• Missing Implementation: Develop and deploy scripts for certificate generation with shorter validity periods. Implement automated renewal reminders.

Mitigation Strategy: Clearly Define Certificate Scope and Purpose

• Description:
  1. Document Approved Usage: Create clear and concise documentation that explicitly states that mkcert certificates are ONLY for local development and testing.
  2. Prohibit Production Usage: Explicitly state that mkcert certificates MUST NOT be used in production, staging, or any publicly accessible environments.
  3. Onboarding and Training: Incorporate this scope definition into developer onboarding materials.
  4. Code Comments and Reminders: Include comments in relevant code sections (e.g., configuration files, deployment scripts) reminding developers about the restricted scope of mkcert certificates.
• List of Threats Mitigated:
  • Threat: Accidental Production Usage (High Severity) - Prevents developers from mistakenly deploying mkcert certificates to production, which would lead to browser trust issues and potential security warnings for users.
  • Threat: Misunderstanding of mkcert's Role (Low Severity) - Clarifies the intended use of mkcert and prevents developers from misusing it as a general-purpose certificate authority.
• Impact: Medium Risk Reduction - Primarily reduces the risk of accidental misconfiguration and misuse due to lack of clarity.
• Currently Implemented: Partially Implemented - Scope is mentioned in onboarding documentation, but not consistently reinforced in code or automated checks.
• Missing Implementation: Add explicit warnings in code templates and deployment scripts. Implement automated checks to detect mkcert certificate usage in non-development environments.

Mitigation Strategy: Automated Checks to Prevent Production Usage

• Description:
  1. Identify mkcert Certificate Characteristics: Determine unique characteristics of mkcert-generated certificates (e.g., issuer name in the certificate, file path conventions).
  2. Implement Pipeline Checks: Integrate automated checks into the CI/CD pipeline and deployment processes.
  3. Certificate File Path Checks: In deployment scripts, verify that certificate file paths are configured to point to trusted CA certificates and not local mkcert paths.
  4. Certificate Content Inspection: Implement scripts to inspect certificate files being deployed and check for mkcert issuer names or other identifying characteristics.
  5. Fail Deployment on Detection: Configure the automated checks to fail the deployment process if mkcert-like certificates are detected in production configurations.
• List of Threats Mitigated:
  • Threat: Accidental Production Usage (High Severity) - Provides a strong technical control to prevent the deployment of mkcert certificates to production environments.
• Impact: High Risk Reduction - Significantly reduces the risk of accidental production deployment of inappropriate certificates.
• Currently Implemented: No Implementation - No automated checks are currently in place to prevent production usage of mkcert certificates.
• Missing Implementation: Develop and integrate automated checks into the CI/CD pipeline and deployment scripts.

Mitigation Strategy: Clear Documentation and Guidelines

• Description:
  1. Create Dedicated Documentation: Develop a specific document or section in the development guidelines dedicated to mkcert usage.
  2. Document Best Practices: Clearly document all the recommended mitigation strategies and best practices for using mkcert securely.
  3. Provide Step-by-Step Instructions: Include step-by-step instructions for generating, using, and managing mkcert certificates.
  4. Include Warnings and Prohibitions: Explicitly include warnings against production usage and emphasize the importance of securing the Root CA private key.
  5. Removal Instructions: Provide clear instructions on how to remove the mkcert Root CA from the system trust store when it's no longer needed.
• List of Threats Mitigated:
  • Threat: Misconfiguration due to Lack of Knowledge (Medium Severity) - Provides developers with the necessary information to use mkcert correctly and securely, reducing misconfigurations.
  • Threat: Inconsistent Practices (Low Severity) - Ensures consistent and standardized usage of mkcert across the development team.
• Impact: Medium Risk Reduction - Improves consistency and reduces errors due to lack of information and clear guidelines.
• Currently Implemented: Partially Implemented - Some documentation exists, but it's not comprehensive and lacks detailed guidelines on all mitigation strategies.
• Missing Implementation: Create a dedicated and comprehensive mkcert usage guide, incorporating all best practices and mitigation strategies.