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Threat Model Analysis for stripe/stripe-python

Threat: Forged Webhook Events

  • Threat: Forged Webhook Events
    • Description: An attacker sends crafted HTTP requests to the application's Stripe webhook endpoint, mimicking legitimate webhook events from Stripe. If the application doesn't verify the webhook signature, the attacker can trigger unauthorized actions (e.g., marking orders as paid, creating fraudulent refunds).
    • Impact:
      • Data corruption (e.g., incorrect order statuses, fraudulent transactions).
      • Financial loss.
      • Potential for further attacks by exploiting the application's webhook handling logic.
    • Affected Component: stripe.Webhook.construct_event (and the application's webhook handling logic in general). The vulnerability exists if this function is not used or is used incorrectly.
    • Risk Severity: High
    • Mitigation Strategies:
      • Always verify webhook signatures using stripe.Webhook.construct_event(payload, sig_header, endpoint_secret). This is the primary defense.
      • Obtain the endpoint_secret from the Stripe Dashboard (Webhook settings).
      • Handle potential exceptions raised by construct_event (e.g., stripe.error.SignatureVerificationError).
      • Implement idempotency checks to prevent duplicate processing of the same webhook event (using the Event object's ID).
      • Secure the webhook endpoint with appropriate network security measures (e.g., firewall rules, IP whitelisting if possible).
      • Log all webhook events (including failed verification attempts) for auditing and debugging.

Threat: Double Charging Customers via Idempotency Key Misuse

  • Threat: Double Charging Customers via Idempotency Key Misuse
    • Description: The application attempts to charge a customer but encounters a network error or timeout. Without proper idempotency key handling, a retry of the same charge request might result in the customer being charged twice. Alternatively, the application might incorrectly reuse the same idempotency key for different charges.
    • Impact:
      • Customer dissatisfaction and chargebacks.
      • Financial loss (due to refunds and fees).
      • Reputational damage.
    • Affected Component: Any stripe-python function that creates charges (e.g., stripe.Charge.create) or performs other idempotent operations. The idempotency_key parameter is the key element.
    • Risk Severity: High
    • Mitigation Strategies:
      • Always use idempotency keys for sensitive operations like creating charges, creating customers, or initiating payouts.
      • Generate a unique idempotency key for each distinct request. A common approach is to use a UUID (Universally Unique Identifier).
      • Store the idempotency key and its associated request details (e.g., in a database) to track the status of the request.
      • If a request fails, check if an idempotency key was used and if a corresponding record exists. If so, you can safely retry the request with the same idempotency key.
      • Do not reuse idempotency keys for different requests.
      • Understand Stripe's idempotency key behavior (keys are valid for 24 hours).

Threat: Using an Outdated stripe-python Version

  • Threat: Using an Outdated stripe-python Version
    • Description: The application uses an old version of the stripe-python library that contains known vulnerabilities or lacks important security updates. An attacker could exploit these vulnerabilities to compromise the application or the Stripe account.
    • Impact:
      • Vulnerability to known exploits.
      • Potential for data breaches or financial loss.
      • Non-compliance with PCI DSS (if handling card data).
    • Affected Component: The entire stripe-python library.
    • Risk Severity: High
    • Mitigation Strategies:
      • Regularly update the stripe-python library to the latest version using pip install --upgrade stripe.
      • Monitor Stripe's security advisories and release notes for any vulnerabilities.
      • Use dependency management tools (e.g., pip, poetry, requirements.txt) to track and manage library versions.
      • Automate dependency updates as part of the CI/CD pipeline (e.g., using Dependabot or similar tools).
      • Test the application thoroughly after updating dependencies.