threat-modeling.md

Threat Model Analysis for psf/requests

Threat: Man-in-the-Middle Attack via Disabled Certificate Verification

• Description: An attacker positions themselves between the application and the server (e.g., on a compromised network). The application explicitly disables SSL/TLS certificate verification in the requests call, allowing the attacker to present a fake certificate and intercept/modify the communication without detection.
• Impact: Complete compromise of communication confidentiality and integrity. The attacker can steal credentials, inject malicious data, or impersonate the server, leading to data breaches, account takeovers, and other severe consequences.
• Affected Component: Any requests function that makes HTTPS requests (e.g., requests.get(), requests.post(), etc.) when used with verify=False.
• Risk Severity: Critical
• Mitigation Strategies:
  • Never disable certificate verification in production: Always use verify=True (the default). This is the most crucial mitigation.
  • Use trusted CAs: Ensure the certifi package (used by requests) is up-to-date, providing a reliable set of root certificates.
  • Careful testing with self-signed certs: If using self-signed certificates during development only, use a dedicated configuration setting that is absolutely never enabled in production. Ideally, set up a temporary, trusted CA for development purposes.

Threat: Denial of Service via Missing Timeouts

• Description: An attacker crafts requests to a slow or unresponsive server, or the target server becomes unresponsive for legitimate reasons. The application does not set timeouts on requests calls. The application will wait indefinitely for a response, consuming resources (threads, memory) and eventually becoming unresponsive itself, leading to a denial-of-service.
• Impact: Application unavailability, resource exhaustion (potentially affecting other applications or the entire system if resources are shared), and potential for complete system failure in extreme cases.
• Affected Component: requests.get(), requests.post(), requests.put(), requests.delete(), requests.head(), requests.options(), requests.patch(), and any requests.Session methods that make network requests, when used without the timeout parameter.
• Risk Severity: High
• Mitigation Strategies:
  • Always set timeouts: Use the timeout parameter in all requests calls (e.g., requests.get(url, timeout=5)). This is the primary mitigation.
  • Choose appropriate timeouts: Base timeout values on the expected response time of the target service, considering network latency and potential delays. Start with relatively short timeouts and adjust as needed.
  • Implement retries with backoff (with a maximum timeout): Use a retry mechanism with exponential backoff to handle transient network issues, but always enforce a maximum overall timeout to prevent indefinite waiting.

Threat: Sending Sensitive Data to Incorrect Endpoint

• Description: Due to a coding error (e.g., incorrect variable usage, typo in a hardcoded URL, flawed logic in URL construction), sensitive data (credentials, API keys, PII) intended for a secure, trusted endpoint is accidentally sent to an external, untrusted, or even malicious endpoint controlled by an attacker.
• Impact: Exposure of sensitive data to unauthorized parties, leading to potential data breaches, account compromise, financial loss, and reputational damage. The attacker gains access to information they should not have.
• Affected Component: Any requests function used to send data (e.g., requests.get(), requests.post(), requests.put(), requests.request(), etc.), where the URL argument is constructed or obtained incorrectly. This is a direct misuse of the destination to which requests sends data.
• Risk Severity: High
• Mitigation Strategies:
  • Code Review: Thoroughly review code that constructs or handles URLs, paying close attention to variable assignments, string formatting, and any logic that determines the target endpoint.
  • Input Validation: If URLs are derived from user input or external sources, rigorously validate them to ensure they conform to expected patterns and point to trusted endpoints. Use allow-lists rather than deny-lists.
  • Environment Variables: Use environment variables to manage endpoint URLs, making it easier to distinguish between internal/external and development/production environments, and reducing the risk of hardcoding errors.
  • Testing: Implement comprehensive tests, including unit tests and integration tests, to verify that requests are sent to the correct endpoints, especially when dealing with sensitive data.
  • Service Discovery: Consider using a service discovery mechanism to dynamically resolve endpoint URLs, reducing the reliance on hardcoded values and minimizing the risk of errors.

Threat: Denial of Service via Large Response Handling

• Description: An attacker crafts a request that results in a very large response (e.g., a large file download or an unexpectedly large JSON payload). The application does not use streaming and attempts to load the entire response into memory at once.
• Impact: Memory exhaustion, application crashes, denial of service. The application becomes unresponsive or terminates unexpectedly.
• Affected Component: Any requests function that receives a response, when used without stream=True and without proper handling of large responses (chunking). This directly relates to how requests handles the response body.
• Risk Severity: High
• Mitigation Strategies:
  • Use streaming: Set stream=True in requests calls when expecting potentially large responses. This is the primary mitigation.
  • Process in chunks: Use response.iter_content() or response.iter_lines() to process the response body in manageable chunks, avoiding loading the entire response into memory at once.
  • Set size limits: Implement a maximum response size limit and abort the request if the Content-Length header (if present and reliable) indicates that the response will exceed this limit. Even with streaming, consider a timeout to prevent excessively long downloads.