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Attack Tree Analysis for onevcat/kingfisher

Objective: To gain unauthorized access to sensitive data, manipulate application behavior, or cause a denial-of-service (DoS) by exploiting vulnerabilities or misconfigurations in the Kingfisher image loading and caching library.

Attack Tree Visualization

                                      Compromise Application via Kingfisher [CRITICAL]
                                                  |
        -------------------------------------------------------------------------
        |																										 |
  1. Data Exposure/Leakage																						  1. Data Exposure/Leakage
        |																										 |
  -------------																						  -------------
  |																										 |
1.2  Image																												1.1 Cache
Source																												Poisoning
Manipulation
  |																												|
1.2.1 [CRITICAL]																										1.1.1
-> HIGH RISK ->																										Shared
Replace																											Cache
Legitimate																										Exploit
Image URL
-> HIGH RISK ->
with
Malicious
URL

Attack Tree Path: 1. Data Exposure/Leakage (via Image Source Manipulation)

  • 1.2.1 Replace Legitimate Image URL with Malicious URL [CRITICAL]:
    • Description: The attacker provides a malicious URL instead of a legitimate image URL to the application. This malicious URL could point to a server controlled by the attacker, allowing them to return arbitrary content disguised as an image.
    • How it works: The application, lacking proper input validation, passes the attacker-supplied URL directly to Kingfisher. Kingfisher then fetches the content from the malicious URL. The attacker's server can then return:
      • A seemingly valid image containing hidden data (steganography).
      • An image designed to exploit vulnerabilities in the image display component (not Kingfisher itself, but the component rendering the image, e.g., a UIImageView).
      • An image that redirects to a phishing site or triggers other malicious actions when displayed.
    • Likelihood: High (If user input directly influences the image URL without proper validation.)
    • Impact: High (Potential for data exfiltration, phishing, or exploitation of image display vulnerabilities.)
    • Effort: Low (Simply providing a malicious URL.)
    • Skill Level: Novice (Basic understanding of URLs.)
    • Detection Difficulty: Easy (If proper input validation and logging are in place. Malicious URLs can be identified.)
    • Mitigation:
      • Strict URL Validation and Whitelisting: Do not allow arbitrary URLs. Validate URLs against a strict whitelist of allowed domains and paths. Use a robust URL parsing library.
      • Sanitize User Input: Thoroughly sanitize any user-provided data that contributes to the image URL.
      • Proxy/Intermediary: Fetch images through a trusted proxy that performs validation and sanitization.

Attack Tree Path: 2. Data Exposure/Leakage (via Cache Poisoning)

  • 1.1.1 Shared Cache Exploit: * Description: The attacker exploits a shared caching environment (e.g., a CDN or proxy) where Kingfisher's cache is not properly isolated between different users or applications. The attacker replaces a legitimate cached image with a malicious one. * How it works:
    • The attacker identifies a shared cache used by Kingfisher.
    • The attacker requests a specific image URL with manipulated parameters (or uses other cache poisoning techniques) to cause the cache to store their malicious image under a key that will be used by legitimate users.
    • Subsequent users requesting the same image (using the same cache key) will receive the attacker's malicious image from the cache. * Likelihood: Medium (Depends heavily on the deployment environment. Lower if proper cache isolation is used.) * Impact: High (Exposure of sensitive images or potential for XSS if image display is vulnerable. Can affect multiple users.) * Effort: Low (If a shared cache is vulnerable, injecting a malicious image is relatively easy.) * Skill Level: Intermediate (Understanding of caching mechanisms and potential injection techniques.) * Detection Difficulty: Medium (Requires monitoring cache contents and network traffic. Might be difficult to distinguish from legitimate cache updates.) * Mitigation:
    • Ensure Proper Cache Isolation: Use separate cache instances or namespaces for different users/applications. If using a shared CDN, ensure strong tenant isolation.
    • Implement Cache Key Validation: Verify that the cache key corresponds to the expected image URL and parameters. Use Kingfisher's cacheKey and originalCacheKey.
    • Strong Cache Control Headers: Set appropriate Cache-Control and Expires headers.
    • Subresource Integrity (SRI): Consider using SRI for the final image display (implemented in the application, not Kingfisher itself).