attack-surface.md

Attack Surface Analysis for vlucas/phpdotenv

Attack Surface: Exposure of .env File

• Description: Unauthorized access to the .env file, which is the primary configuration source for phpdotenv and typically contains sensitive application secrets.
• How phpdotenv Contributes to Attack Surface: phpdotenv's core function is to load configuration from the .env file. This makes the .env file a critical target. If exposed, the secrets intended to be managed by .env and loaded by phpdotenv are directly compromised.
• Example: A web server misconfiguration allows direct access to files. An attacker requests https://example.com/.env and downloads the file, revealing secrets that phpdotenv was intended to load and protect.
• Impact: Critical. Full compromise of application secrets loaded by phpdotenv. This can lead to data breaches, account takeovers, and denial of service.
• Risk Severity: Critical
• Mitigation Strategies:
  • Web Server Configuration: Configure web servers to explicitly deny access to .env files, preventing direct download via web requests.
  • .env File Location: Place the .env file outside the web root, ensuring it's not directly accessible via the web server.
  • File Permissions: Restrict file permissions on the .env file to allow only the application user to read it, preventing unauthorized access.
  • Version Control Exclusion: Exclude .env from version control using .gitignore to prevent accidental exposure in repositories.

Attack Surface: Injection via .env File Modification

• Description: An attacker gains write access to the .env file and modifies its contents to inject malicious configuration values that phpdotenv will load and make available to the application.
• How phpdotenv Contributes to Attack Surface: phpdotenv loads and processes the contents of the .env file without inherent validation. If an attacker can modify this file, phpdotenv will faithfully load and expose the attacker's injected configuration to the application.
• Example: In a development environment with weak permissions, an attacker gains write access and modifies .env to change database credentials to a malicious server. The application, using phpdotenv, loads this modified configuration and connects to the attacker's database.
• Impact: High. Attackers can manipulate application configuration loaded by phpdotenv, potentially leading to configuration manipulation, indirect code injection (if variables are used insecurely), data manipulation, or denial of service.
• Risk Severity: High
• Mitigation Strategies:
  • Restrict File Permissions: Implement strict file permissions to prevent unauthorized write access to the .env file, especially in production environments.
  • Immutable Infrastructure (Production): In production, prefer immutable infrastructure where configuration is baked in, reducing reliance on writable files at runtime.
  • Environment Variable Overrides (Production): In production, prioritize setting environment variables directly via the hosting environment or container orchestration, making .env modification less relevant and impactful.
  • Regular Security Audits: Monitor file system changes and access logs for suspicious modifications to configuration files like .env.

Attack Surface: Misuse of .env Files in Production Environments

• Description: Using .env files directly in production environments, which increases the risk of exposure compared to using more secure environment variable management methods, and is directly related to the common usage pattern encouraged by phpdotenv in development.
• How phpdotenv Contributes to Attack Surface: phpdotenv's ease of use can lead to developers relying on .env files even in production, where they become a persistent and potentially vulnerable point of configuration if not properly secured.
• Example: An application is deployed to production, and developers continue to use a .env file within the application directory. This reliance on a file-based configuration in production increases the attack surface for .env file exposure, a risk directly associated with phpdotenv's usage pattern.
• Impact: High. Increased probability of .env file exposure in production, leading to critical impacts like data breaches and system compromise.
• Risk Severity: High
• Mitigation Strategies:
  • Avoid .env in Production: Do not rely on .env files in production environments.
  • Use Environment Variables Directly (Production): Utilize environment variable mechanisms provided by the production hosting environment, container orchestration, or server configuration for secure secret management.
  • Secret Management Tools (Production): For complex environments, use dedicated secret management tools to securely store and inject secrets, instead of relying on file-based configuration in production.
  • Educate Developers: Train developers on secure secret management practices and the risks of using .env files directly in production, emphasizing environment-specific configuration methods.