attack-surface.md

Attack Surface Analysis for stripe/stripe-python

Attack Surface: Stripe API Key Exposure

• Description: Accidental or intentional disclosure of Stripe API keys, particularly secret keys, which grant broad access to your Stripe account. This is a critical vulnerability when using stripe-python as it relies on these keys for authentication.
• Stripe-Python Contribution: stripe-python requires API keys to be configured for authentication to interact with the Stripe API. While the library itself doesn't expose keys, its fundamental requirement for API keys makes insecure key management a direct attack surface when using stripe-python.
• Example:
  • A developer using stripe-python hardcodes the Stripe secret key directly into a Python file, which is then exposed.
  • When configuring stripe-python, the secret key is stored in an insecure environment variable accessible to unauthorized users.
• Impact: Full compromise of your Stripe account, potentially leading to:
  • Unauthorized access to sensitive customer and financial data managed through Stripe.
  • Fraudulent transactions and significant financial losses processed via Stripe.
  • Reputational damage and legal liabilities due to data breaches and financial fraud related to Stripe operations.
• Risk Severity: Critical
• Mitigation Strategies:
  • Never hardcode API keys in code used with stripe-python.
  • Utilize secure secrets management systems (e.g., HashiCorp Vault, AWS Secrets Manager, cloud provider secret services) to store and manage API keys used by stripe-python.
  • Restrict access to environments and systems where API keys for stripe-python are stored.
  • Employ restricted API keys with the principle of least privilege when configuring stripe-python.
  • Implement regular API key rotation for keys used with stripe-python.
  • Scan code and configuration files for accidentally exposed API keys before committing changes when working with stripe-python integrations.
  • Never expose secret keys in client-side code when using stripe-python in backend systems.

Attack Surface: Insufficient Key Scoping/Permissions

• Description: Using overly permissive Stripe API keys (like secret keys) with stripe-python when restricted keys with narrower permissions would be more secure. This increases the potential damage if a key used by stripe-python is compromised.
• Stripe-Python Contribution: stripe-python can be configured with any type of Stripe API key. The library itself does not enforce key scoping. The risk arises directly from the application's choice of API key used in conjunction with stripe-python.
• Example:
  • An application uses the secret key for all stripe-python operations, even for tasks that could be performed with a restricted key (e.g., creating charges only).
  • If this secret key, used throughout the stripe-python integration, is compromised, the impact is far greater than if a restricted key with limited permissions had been used.
• Impact: If an API key used by stripe-python is compromised, the attacker gains broader access and can perform more actions than necessary within your Stripe account, potentially leading to greater damage, including unauthorized data access and wider fraudulent activities.
• Risk Severity: High
• Mitigation Strategies:
  • Principle of Least Privilege: Always configure stripe-python with the most restricted API key possible for each specific task.
  • Utilize Stripe's restricted keys feature to create keys with granular permissions (e.g., read-only access, create charges only, etc.) and use these with stripe-python where appropriate.
  • Carefully review the required permissions for each part of your application's Stripe integration that uses stripe-python and choose the most restrictive suitable key type.
  • Regularly audit API key usage in your stripe-python integrations to ensure keys are scoped correctly and not overly permissive.

Attack Surface: Information Disclosure through Stripe API Interactions

• Description: Unintentionally exposing sensitive information obtained from the Stripe API when using stripe-python, due to insecure handling of API responses or excessive data retrieval.
• Stripe-Python Contribution: stripe-python is the mechanism used to interact with the Stripe API and retrieve data. If the application using stripe-python doesn't handle this retrieved data securely, information disclosure vulnerabilities arise directly from the data accessed via stripe-python.
• Example:
  • An application using stripe-python retrieves full customer objects from Stripe when only the customer ID is needed. The full object, containing PII and payment details obtained via stripe-python, is then logged insecurely.
  • Error messages from stripe-python or the Stripe API, containing sensitive details from Stripe interactions, are displayed directly to users or logged in an insecure manner.
• Impact: Exposure of sensitive customer data (PII, payment information, transaction history) retrieved via stripe-python, potentially leading to:
  • Privacy violations and regulatory non-compliance (e.g., GDPR, PCI DSS) due to mishandling data accessed through stripe-python.
  • Reputational damage and loss of customer trust stemming from data breaches involving Stripe data accessed via stripe-python.
  • Increased risk of identity theft or fraud against customers whose data was exposed through insecure stripe-python usage.
• Risk Severity: High
• Mitigation Strategies:
  • Principle of Least Privilege (Data Retrieval): When using stripe-python, only retrieve the minimum necessary data from the Stripe API. Use API parameters to filter and limit the data returned by stripe-python.
  • Secure Logging Practices: Avoid logging sensitive data from Stripe API responses obtained via stripe-python. If logging is necessary, redact or mask sensitive fields before logging data retrieved by stripe-python.
  • Sanitize and Filter API Responses: Before displaying or processing data from Stripe API responses obtained via stripe-python, carefully sanitize and filter it to remove any sensitive or unnecessary information.
  • Avoid Direct Exposure of Raw API Responses: Never directly expose raw Stripe API responses obtained through stripe-python to users. Transform and present data in a user-friendly and secure manner.
  • Implement proper error handling: Avoid displaying verbose error messages to users that might reveal sensitive information from Stripe API interactions via stripe-python.

Attack Surface: Webhook Security Issues (If Webhooks are Used)

• Description: Vulnerabilities related to handling Stripe webhooks when using stripe-python, including improper verification and insecure webhook handlers.
• Stripe-Python Contribution: stripe-python provides essential utilities for verifying webhook signatures. The application's responsibility is to correctly use these stripe-python utilities and implement secure webhook handlers. Failure to properly utilize stripe-python's verification features directly leads to this attack surface.
• Example:
  • An application's webhook handler, intended to use stripe-python for verification, fails to correctly implement signature verification, allowing attackers to send forged webhook events.
  • Even with stripe-python's verification, the webhook handler logic itself has vulnerabilities, such as blindly trusting webhook data without validation after (or even before) using stripe-python for signature checks.
• Impact:
  • Application state manipulation and data corruption due to processing forged webhooks that bypass stripe-python's intended security measures or application logic.
  • Bypassing payment processing or other critical business logic if webhook handling, even with stripe-python verification, is flawed.
• Risk Severity: High
• Mitigation Strategies:
  • Always Verify Webhook Signatures: Utilize stripe-python's webhook signature verification utilities correctly and consistently to ensure webhook events are genuinely from Stripe and haven't been tampered with.
  • Secure Webhook Handler Logic: Thoroughly validate and sanitize all data received from webhooks, even after signature verification using stripe-python. Implement robust error handling and security checks within webhook handlers.
  • Secure Webhook Endpoint: Ensure the webhook endpoint is properly secured (e.g., HTTPS, appropriate network security) in conjunction with secure webhook handling using stripe-python.
  • Test Webhook Handling Thoroughly: Rigorous testing of webhook handling logic, including signature verification using stripe-python, error conditions, and malicious webhook payloads, is crucial.