attack-surface.md

Attack Surface Analysis for bkeepers/dotenv

Attack Surface: Exposure of .env File in Version Control Systems

• Description: Accidental or intentional committing of the .env file, containing sensitive environment variables, to version control repositories like Git. This makes secrets publicly or internally accessible through the repository history.
• How dotenv Contributes: dotenv promotes the use of a .env file as the primary method for managing environment variables, making it a central file that developers might mistakenly include in version control. The library's documentation and common usage patterns often lead developers to create and manage this specific file.
• Example: A developer initializes a new project and uses dotenv. They forget to add .env to .gitignore and commit the file containing production database credentials and API keys to a public GitHub repository. Attackers scanning public repositories for secrets discover the commit and gain access to sensitive resources.
• Impact: Critical Information disclosure of highly sensitive credentials (database passwords, API keys, secret keys). This can lead to immediate and widespread unauthorized access to critical systems, data breaches, financial loss, severe reputational damage, and potential legal repercussions.
• Risk Severity: Critical
• Mitigation Strategies:
  • Strictly exclude .env from version control: Always add .env to .gitignore and rigorously enforce this practice.
  • Automated pre-commit checks: Implement pre-commit hooks that automatically prevent commits containing .env files.
  • Repository scanning for secrets: Utilize tools that scan repositories for accidentally committed secrets and alert developers.
  • Developer training and awareness: Educate developers on the extreme risks of committing .env files and best practices for secret management.

Attack Surface: Insecure Storage of .env File on Server

• Description: Storing the .env file on the server in a location accessible to unauthorized users or processes, or with overly permissive file permissions. This allows attackers with server access to easily retrieve sensitive configuration.
• How dotenv Contributes: dotenv relies on reading a file from the file system to load environment variables. If the server environment is not properly secured, this file becomes a high-value target for attackers. The library's design necessitates the presence of this file on the server, increasing the risk if server security is weak.
• Example: A .env file containing database credentials is placed in the web server's document root with overly permissive file permissions (e.g., world-readable). An attacker exploits a local file inclusion (LFI) vulnerability in the web application or gains shell access through other means and directly reads the .env file, obtaining sensitive credentials.
• Impact: Critical Information disclosure of sensitive credentials, granting attackers unauthorized access to backend systems, databases, and external services. This can lead to data breaches, data manipulation, and complete system compromise.
• Risk Severity: Critical
• Mitigation Strategies:
  • Restrict file permissions: Set file permissions on the .env file to be readable only by the application's user and necessary system processes (e.g., 600 or 640).
  • Secure storage location: Store the .env file outside the web server's document root and in a protected directory inaccessible via web requests.
  • Principle of least privilege: Run the application process with the minimum necessary permissions to limit the impact if the application or server is compromised.
  • Server hardening: Implement robust server security measures to prevent unauthorized access to the file system in the first place.

Attack Surface: Environment Variable Injection via .env Manipulation

• Description: An attacker gains write access to the server's file system and modifies the .env file to inject malicious or altered environment variables. This allows them to control application behavior by manipulating its configuration.
• How dotenv Contributes: dotenv directly reads and applies the contents of the .env file to the application's environment. If an attacker can modify this file, they can directly influence the application's configuration loaded by dotenv. The library's trust in the .env file content makes it a potent attack vector if write access is compromised.
• Example: An attacker exploits a vulnerability (e.g., file upload vulnerability, remote code execution) and gains write access to the server. They modify the .env file to change the database connection string to point to a malicious database server under their control. When the application restarts or reloads configuration, it connects to the attacker's database, potentially leaking sensitive data or executing malicious queries.
• Impact: High to Critical Configuration tampering leading to data manipulation, redirection to malicious resources, privilege escalation (if environment variables control access), and potentially denial of service or further exploitation depending on how the application uses environment variables. In severe cases, it could lead to arbitrary code execution if environment variables are used in unsafe ways within the application.
• Risk Severity: High to Critical
• Mitigation Strategies:
  • Strictly restrict write access: Ensure that the .env file and its directory are not writable by the web server process or any potentially compromised accounts. Implement strong access controls.
  • File integrity monitoring: Implement file integrity monitoring systems to detect unauthorized modifications to the .env file and trigger alerts.
  • Immutable infrastructure (preferred for production): In production environments, consider moving away from file-based configuration and towards immutable infrastructure where configuration is baked into deployment images, eliminating the runtime modifiable .env file.
  • Input validation and sanitization (application level): While less effective against direct .env manipulation, validate and sanitize environment variables within the application before using them, especially for critical operations, as a defense-in-depth measure.

Attack Surface: Parsing Vulnerabilities in dotenv Library

• Description: Vulnerabilities within the dotenv library's parsing logic itself could potentially be exploited. While less frequent in mature libraries, parsing bugs can lead to unexpected behavior or security flaws if specially crafted .env files are processed.
• How dotenv Contributes: The application's security becomes dependent on the security of its dependencies, including dotenv. If dotenv has a parsing vulnerability, it can be indirectly exploited when processing .env files. The library's core function is parsing this file, making parsing vulnerabilities a direct concern.
• Example: A hypothetical vulnerability in dotenv's parsing logic allows for command injection if a specially crafted .env file with malicious syntax is processed. If an attacker can somehow influence the content of the .env file (e.g., in development environments or through less secure deployment practices), they could exploit this vulnerability to execute arbitrary commands on the server when the application loads the configuration.
• Impact: High to Critical Depending on the nature of the parsing vulnerability, impacts could range from denial of service and configuration manipulation to, in more severe cases, arbitrary code execution on the server.
• Risk Severity: High (potentially Critical if RCE is possible)
• Mitigation Strategies:
  • Regularly update dependencies: Keep the dotenv library and all other dependencies updated to the latest versions to benefit from bug fixes and security patches.
  • Dependency scanning and vulnerability monitoring: Use dependency scanning tools to identify known vulnerabilities in project dependencies, including dotenv, and monitor for new vulnerabilities.
  • Security audits and code reviews: Include dependency security reviews in regular security audits and code reviews of the application to assess potential risks from libraries like dotenv.
  • Consider alternative configuration methods (for highly sensitive applications): For applications with extreme security requirements, evaluate if relying on a file-based configuration library like dotenv is the most secure approach, or if more robust and less parsing-dependent alternatives are available for production.