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Threat Model Analysis for dart-lang/http

Threat: URL Redirection/SSRF (Server-Side Request Forgery)

  • 1. Threat: URL Redirection/SSRF (Server-Side Request Forgery)

    • Description: An attacker crafts malicious input that, when used to construct the URL for an http request, redirects the request to an unintended destination. The attacker might target internal services, cloud metadata endpoints (e.g., 169.254.169.254 on AWS, GCP, Azure), or other servers the application server can reach but the attacker cannot directly access. They might use schemes like file:// or gopher:// to interact with local services. The http package's functions are directly used to make the manipulated request.
    • Impact: Unauthorized access to internal resources, data exfiltration, potential remote code execution on internal systems, denial of service against internal or external targets.
    • Affected Component: http.get(), http.post(), http.put(), http.delete(), http.head(), http.patch(), and any other functions that accept a URL as input (directly or indirectly through a Request object). The Uri class is also directly involved, as it's used to construct URLs.
    • Risk Severity: High to Critical (depending on the network environment and accessible resources).
    • Mitigation Strategies:
      • Strict Input Validation: Validate all user-supplied input used in URL construction using a whitelist approach. Allow only specific, expected characters and patterns. Reject any input containing suspicious characters or schemes.
      • Use Uri Class Correctly: Always use the Uri class's named constructors (e.g., Uri.https(), Uri.http()) to build URLs. Avoid string concatenation. Use the queryParameters argument for query parameters, rather than manually encoding them.
      • URL Allowlist: If possible, maintain a list of allowed URLs or URL prefixes. Reject any request that doesn't match the allowlist.
      • Network Segmentation: Limit the network access of the application server to reduce the impact of successful SSRF attacks.
      • Avoid Relative URLs with Untrusted Base URLs: If using relative URLs, ensure the base URL is a trusted, hardcoded value, not derived from user input.

Threat: Insecure TLS Configuration

  • 2. Threat: Insecure TLS Configuration

    • Description: The attacker exploits a misconfigured TLS setup within the http package usage. This could involve the application accepting invalid or self-signed certificates without proper verification, or using weak cipher suites. This is most likely to occur when developers override the default TLS behavior using IOClient and a custom SecurityContext, or by misusing badCertificateCallback. The vulnerability is directly tied to how TLS is handled within the http client's configuration.
    • Impact: Man-in-the-middle (MITM) attacks, allowing the attacker to intercept and modify communication between the client and server, leading to data breaches and potential compromise of credentials.
    • Affected Component: IOClient (when used with a custom SecurityContext), badCertificateCallback (if improperly implemented).
    • Risk Severity: Critical.
    • Mitigation Strategies:
      • Never Disable Certificate Verification in Production: Use the default http client behavior, which relies on the system's trusted certificate store.
      • Use SecurityContext.defaultContext: If you need a custom SecurityContext, start with SecurityContext.defaultContext and modify it carefully.
      • Certificate Pinning: Implement certificate pinning to verify that the server's certificate matches a known, trusted certificate.
      • Strong Cipher Suites: Ensure that the application and server are configured to use strong, modern cipher suites.
      • Regularly Update CA Certificates: Keep the system's trusted CA certificates up to date.
      • Avoid badCertificateCallback Unless Absolutely Necessary: If you must use badCertificateCallback (e.g., for testing), ensure it's implemented securely and only used in controlled environments. Never blindly return true.

Threat: Header Injection (Focus on Client-Side)

  • 3. Threat: Header Injection (Focus on Client-Side)
    • Description: While header injection is often a server-side concern, misuse of the http package can enable it. If an attacker can control the values passed to the headers parameter of http methods (or the Request object), they might be able to inject headers that, while not directly exploitable on the client, could be used to exploit vulnerabilities on the server. This is a subtle but important distinction. The http package is the conduit for the injected headers. The focus here is on the client-side creation of the malicious request.
    • Impact: Potentially bypassing security controls on the server, cache poisoning, request smuggling (though less likely), influencing application logic on the server-side. The impact is realized on the server, but the vulnerability originates in the client's use of http.
    • Affected Component: The headers parameter of http.get(), http.post(), etc., and the headers property of the Request object.
    • Risk Severity: High (because the impact is on the server, and could be severe).
    • Mitigation Strategies:
      • Input Validation: Rigorously validate any user-supplied data used to construct headers. Avoid directly using user input as header values without sanitization.
      • Whitelist Allowed Headers: If possible, restrict the set of headers that the application is allowed to set.
      • Use a Dedicated Header Management Function: Create a function or class that handles setting headers, ensuring consistent and secure header construction, and preventing the injection of arbitrary headers.
      • Avoid CRLF Sequences: Ensure that user input cannot inject carriage return/line feed (CRLF) characters ( ) into headers. While the http package and Uri class should handle this correctly if used properly, it's crucial to be aware of this potential issue and validate input accordingly.