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Threat Model Analysis for onevcat/kingfisher

Threat: Malicious Image Source Spoofing

  • Threat: Malicious Image Source Spoofing

    • Description: An attacker crafts a malicious URL or manipulates a legitimate URL to point to a server they control. They then trick the application into passing this URL to Kingfisher, causing it to download and display a malicious image instead of the intended one. This could be done through input fields that influence image URLs, compromised external services that provide image URLs, or DNS spoofing.
    • Impact: Display of inappropriate or offensive content, phishing attacks (displaying a fake login screen), potential exploitation of vulnerabilities in image parsing libraries (though less likely, this is still a potential consequence of displaying a malicious image).
    • Affected Kingfisher Component: ImageDownloader, KingfisherManager.shared.retrieveImage(...), any function that takes a URL as input.
    • Risk Severity: High
    • Mitigation Strategies:
      • Strict URL Validation: Before passing any URL to Kingfisher, rigorously validate it. Use allowlists of trusted domains, validate the URL scheme (HTTPS only), and reject URLs with suspicious characters.
      • HTTPS Enforcement: Ensure Kingfisher only downloads images over HTTPS. Do not disable the default HTTPS preference.
      • Certificate Pinning (Optional): For high-security applications, consider certificate pinning for the image servers.
      • Secure URL Source: If image URLs come from an external service, ensure that service is secure and uses strong authentication/authorization.

Threat: Sensitive Information in Cache Keys

  • Threat: Sensitive Information in Cache Keys

    • Description: The application uses image URLs that contain sensitive information (e.g., session tokens, user IDs) as part of the URL. Kingfisher, by default, uses the URL as the cache key. This sensitive information is then stored in plain text within the cache.
    • Impact: Leakage of sensitive information if an attacker gains access to the cache (e.g., through device theft or a separate vulnerability).
    • Affected Kingfisher Component: ImageCache, specifically the key generation logic.
    • Risk Severity: High
    • Mitigation Strategies:
      • Cache Key Sanitization: Never use raw URLs containing sensitive data as cache keys. Use a CacheKeyFilter or manually create a sanitized version of the URL (e.g., by removing sensitive parameters) or a hash of the URL. Kingfisher provides mechanisms for customizing the cache key.
      • Avoid Sensitive Data in URLs: Ideally, avoid including sensitive information in image URLs altogether. Use alternative methods for authentication and authorization (e.g., HTTP headers).

Threat: Cache Poisoning (via URL Manipulation)

  • Threat: Cache Poisoning (via URL Manipulation)

    • Description: Similar to "Malicious Image Source Spoofing," but with a focus on long-term impact. An attacker injects a malicious URL, and Kingfisher caches the malicious image. Subsequent requests for the intended image will retrieve the malicious version from the cache, even if the original vulnerability (e.g., the input field) is fixed.
    • Impact: Persistent display of malicious content, even after the initial attack vector is closed.
    • Affected Kingfisher Component: ImageDownloader, ImageCache.
    • Risk Severity: High
    • Mitigation Strategies:
      • All Mitigations from "Malicious Image Source Spoofing": Strict URL validation, HTTPS enforcement, etc., are crucial.
      • Short Cache Expiration: Use relatively short cache expiration times to limit the duration of any successful cache poisoning attack.
      • Cache Clearing (Reactive): If cache poisoning is suspected, provide a mechanism for users or administrators to clear the Kingfisher cache.

Threat: Exploitation of Image Parsing Vulnerabilities

  • Threat: Exploitation of Image Parsing Vulnerabilities

    • Description: An attacker crafts a malicious image that exploits a vulnerability in the underlying image decoding libraries used by the operating system (e.g., ImageIO on iOS/macOS). Kingfisher downloads this image, and the system's image parsing routines are triggered, leading to potential code execution.
    • Impact: Potential code execution with the privileges of the application, leading to data theft, system compromise, or other malicious actions.
    • Affected Kingfisher Component: Indirectly, ImageDownloader (as it fetches the image), but the vulnerability is in the system's image parsing libraries, not Kingfisher itself.
    • Risk Severity: Critical (but depends on the severity of the underlying vulnerability)
    • Mitigation Strategies:
      • Keep System Updated: This is the primary mitigation. Ensure the operating system and its image parsing libraries are up-to-date with the latest security patches. This is outside Kingfisher's control.
      • Sandboxing: Rely on the application sandbox to limit the impact of any successful exploit.
      • Least Privilege: Run the application with the least necessary privileges.