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attack-surface.md

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Attack Surface Analysis for nst/ios-runtime-headers

Attack Surface: 1. Undocumented API Exploitation

  • Description: Attackers leverage knowledge of private APIs to exploit vulnerabilities within those undocumented functions.
    • How ios-runtime-headers Contributes: Provides the header files, revealing function signatures, class structures, and method names, making reverse engineering and vulnerability discovery significantly easier. This is the direct contribution.
    • Example: A private API in CoreTelephony (revealed by the headers) might have an unchecked buffer when processing a specific type of SMS message. An attacker could craft a malicious SMS to trigger a buffer overflow, potentially gaining code execution.
    • Impact: Code execution, privilege escalation, data exfiltration, denial of service.
    • Risk Severity: Critical
    • Mitigation Strategies:
      • Developer: Avoid using private APIs. If unavoidable, perform extensive fuzzing and security testing of the specific API calls. Implement robust input validation and error handling. Dynamic analysis is crucial.
      • User: No direct mitigation; relies on developer actions.

Attack Surface: 2. API Instability and Breakage

  • Description: Private APIs can change or be removed without notice in iOS updates, leading to application crashes, unexpected behavior, or security vulnerabilities.
    • How ios-runtime-headers Contributes: Encourages the use of APIs that are not guaranteed to be stable across iOS versions, making the application reliant on undocumented behavior.
    • Example: An app uses a private API to access a specific system setting. An iOS update changes the format of that setting or removes the API entirely. If error handling is poor, this could lead to a denial-of-service or, if the setting controlled a security feature, a vulnerability.
    • Impact: Application instability, data corruption, denial of service, potential security vulnerabilities due to unexpected behavior or failed security checks.
    • Risk Severity: High
    • Mitigation Strategies:
      • Developer: Avoid private APIs. If unavoidable, use runtime checks (respondsToSelector:, instancesRespondToSelector:, class_respondsToSelector:) to verify API availability before calling it. Implement fallback mechanisms to use alternative (public) APIs or gracefully degrade functionality. Thoroughly test on all supported iOS versions and immediately after each iOS update. Consider how changes to the API could impact security.
      • User: No direct mitigation; relies on developer actions.

Attack Surface: 3. Security Mechanism Bypass

  • Description: Private APIs might offer ways to circumvent security restrictions imposed by the public SDK (e.g., sandbox restrictions, permission checks).
    • How ios-runtime-headers Contributes: Exposes APIs that might not be subject to the same security scrutiny as public APIs, potentially providing unintended access to resources or capabilities. The headers are the direct enabler.
    • Example: A private API in a framework related to file system access might allow writing to a directory outside the application's sandbox, bypassing standard iOS security controls.
    • Impact: Data exfiltration, unauthorized access to system resources, privilege escalation.
    • Risk Severity: High
    • Mitigation Strategies:
      • Developer: Avoid private APIs. If unavoidable, carefully analyze the security implications of each API call. Implement additional security checks (e.g., validating file paths, checking permissions) even if the private API appears to grant access. Assume the private API does not perform the same security checks as a public API.
      • User: No direct mitigation; relies on developer actions.