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attack-surface.md

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Attack Surface Analysis for jverkoey/nimbus

Attack Surface: Malicious Link Handling in NIAttributedLabel

  • Description: Exploitation of custom URL handling within Nimbus's attributed labels to trigger unintended actions.
  • Nimbus Contribution: NIAttributedLabel directly provides the functionality for custom link handling, creating the vulnerability if misused.
  • Example: An attacker crafts a text message with a seemingly harmless link rendered by NIAttributedLabel. The link uses a custom URL scheme (e.g., myapp://exploit?command=deleteData) that, when tapped, triggers a function within the app to delete user data.
  • Impact: Data loss, unauthorized actions, potential for remote code execution (if the link handler interacts with other vulnerable components).
  • Risk Severity: High to Critical (depending on the actions triggered).
  • Mitigation Strategies:
    • Developer:
      • Strict URL Validation: Rigorous validation of all URL components (scheme, host, path, query). Use whitelists for allowed schemes/domains.
      • Safe URL Handling: Never directly execute code based on URL parameters. Use a secure intermediary.
      • System APIs: Prefer SFSafariViewController or ASWebAuthenticationSession for web links to leverage system security.
      • Input Sanitization: Sanitize all input used to construct attributed strings.

Attack Surface: Image Decoding Exploits via NINetworkImageView

  • Description: Exploitation of vulnerabilities in image decoding libraries used by Nimbus to process maliciously crafted images.
  • Nimbus Contribution: NINetworkImageView directly handles image downloading, caching, and display, making it the entry point.
  • Example: An attacker sends a crafted PNG image. NINetworkImageView downloads and decodes it, triggering a buffer overflow in the underlying library, leading to code execution.
  • Impact: Remote code execution, denial of service, application crashes.
  • Risk Severity: Critical.
  • Mitigation Strategies:
    • Developer:
      • Up-to-Date Libraries: Ensure Nimbus and image decoding dependencies are current.
      • System Frameworks: Favor system-provided image decoding (e.g., UIImage, UIImageView) for better maintenance.
      • Sandboxing: Consider sandboxing the image decoding process.
      • Fuzz Testing: Perform fuzz testing on image decoding.
      • Image Validation: Validate basic image properties (dimensions, file type) before decoding.

Attack Surface: Cache Poisoning in NINetworkImageView

  • Description: An attacker injects malicious images into the NINetworkImageView cache via manipulated network responses.
  • Nimbus Contribution: NINetworkImageView's caching mechanism is directly the vulnerable component.
  • Example: Man-in-the-middle attack on HTTP. Attacker replaces a legitimate image with a malicious one. NINetworkImageView caches the malicious image; subsequent requests load the exploit.
  • Impact: Remote code execution (via decoding exploits), display of malicious content, denial of service.
  • Risk Severity: High to Critical (depends on exploitability of the cached image).
  • Mitigation Strategies:
    • Developer:
      • HTTPS Enforcement: Enforce HTTPS for all image downloads.
      • Cache Validation: Implement strong validation (checksums, digital signatures).
      • Isolated Cache: Use a dedicated, isolated cache for network images.
      • Cache Expiration: Use appropriate cache expiration policies.

Attack Surface: JavaScript Bridge Vulnerabilities in NIWebController

  • Description: Exploitation of a weakly secured JavaScript bridge in NIWebController to execute native code from a compromised web context.
  • Nimbus Contribution: NIWebController directly provides the web view and the JavaScript bridge, creating the attack surface.
  • Example: Injected JavaScript in a website loaded in NIWebController calls a poorly validated function exposed via the bridge, accessing sensitive data.
  • Impact: Remote code execution, data theft, privilege escalation, security bypass.
  • Risk Severity: Critical.
  • Mitigation Strategies:
    • Developer:
      • Minimize Bridge: Expose only essential functionality.
      • Strict Input Validation: Validate all input from JavaScript.
      • Secure Coding: Apply secure coding principles to the bridge implementation.
      • WKWebView: Use WKWebView (process isolation) instead of older web components.
      • Content Security Policy (CSP): Implement a strict CSP to restrict JavaScript actions.
      • Sandboxing: Ensure the web view runs in a sandboxed environment.

Attack Surface: Outdated Nimbus Version

  • Description: Using an outdated version of the Nimbus framework that contains known vulnerabilities.
  • Nimbus Contribution: The vulnerability exists within the framework itself.
  • Example: An older version of Nimbus has a known vulnerability in its network image handling. An attacker exploits this vulnerability in an application that hasn't updated Nimbus.
  • Impact: Varies depending on the specific vulnerability, potentially ranging from denial of service to remote code execution.
  • Risk Severity: High to Critical (depending on the vulnerability).
  • Mitigation Strategies:
    • Developer:
      • Regular Updates: Regularly update to the latest stable version of Nimbus.
      • Dependency Management: Use a dependency manager (e.g., CocoaPods, Carthage, Swift Package Manager) to track and update dependencies.
      • Security Advisories: Monitor the Nimbus project (GitHub repository, mailing lists, etc.) for security advisories and promptly apply any necessary patches.