Skip to content

Latest commit

 

History

History
136 lines (105 loc) · 7.99 KB

mitigations.md

File metadata and controls

136 lines (105 loc) · 7.99 KB

Mitigation Strategies Analysis for johnlui/swift-on-ios

Mitigation Strategy: Strict Code Review of the Preloaded Library (.dylib)

  1. Obtain Source Code: Get the complete source code of the .dylib injected by swift-on-ios.
  2. Identify Overridden Functions: List all functions overriding standard C library functions (using dlsym or similar).
  3. Function-by-Function Analysis: For each overridden function:
    • Document the exact reason for the override.
    • Analyze for vulnerabilities:
      • Buffer Overflows: Check strcpy, strcat, sprintf, gets, etc.
      • Format String Vulnerabilities: Check printf, sprintf, fprintf, etc., with user-supplied data.
      • Integer Overflows: Examine arithmetic operations.
      • Logic Errors: Trace execution flow.
      • Input Validation: Ensure proper validation and sanitization.
      • Secure Communication: Verify secure protocols (TLS/SSL) and certificate validation.
    • Document risks and mitigations.
  4. Static Analysis: Use tools like Clang Static Analyzer, SonarQube, Coverity.
  5. Secure Coding Practices: Adhere to C/Objective-C/Swift secure coding guidelines.
  6. Independent Review: Have a different developer conduct a review.

  • Threats Mitigated:

    • Arbitrary Code Execution (Severity: Critical): Memory corruption in the preloaded library could allow arbitrary code execution.
    • Information Disclosure (Severity: High/Critical): Logic errors or insecure data handling could leak sensitive information.
    • Denial of Service (Severity: High): Bugs could cause crashes.
    • Privilege Escalation (Severity: High/Critical): Vulnerabilities could allow gaining application privileges.
    • Bypassing Security Mechanisms (Severity: High/Critical): The library could disable security features.

  • Impact:

    • Arbitrary Code Execution: Reduces risk by fixing memory corruption.
    • Information Disclosure: Reduces risk by ensuring secure data handling.
    • Denial of Service: Reduces risk by fixing crash-causing bugs.
    • Privilege Escalation: Reduces risk by preventing privilege escalation vulnerabilities.
    • Bypassing Security Mechanisms: Reduces risk by preventing new security bypasses.

  • Currently Implemented: (Example - Adapt)

    • Initial code review during development.
    • Clang Static Analyzer in build process.
    • Basic secure coding guidelines.

  • Missing Implementation: (Example - Adapt)

    • Formal, documented function-by-function analysis.
    • Independent security expert review.
    • Documentation of override rationale.
    • Advanced static analysis tools (SonarQube).

Mitigation Strategy: Minimize the Scope of Overrides (within the .dylib)

  1. Identify Essential Overrides: Review the preloaded library and determine the absolute minimum functions that must be overridden.
  2. Remove Unnecessary Overrides: Remove any overrides that are not strictly necessary.
  3. Document Rationale: Clearly document the justification for each remaining override.

  • Threats Mitigated:

    • All threats from Strategy #1 (Severity: Varies): Reduces the attack surface and the likelihood of vulnerabilities. Severity depends on the removed functions.

  • Impact:

    • Reduces overall risk by shrinking the attack surface. Impact is proportional to removed overrides.

  • Currently Implemented: (Example)

    • Some effort to limit overrides during development.

  • Missing Implementation: (Example)

    • Systematic review of all overrides.
    • Formal documentation of rationale.

Mitigation Strategy: Runtime Integrity Checks (Focused on the Preloaded Library)

  1. Hashing:
    • Pre-deployment: Calculate SHA-256 hash of the known good .dylib.
    • Store hash securely in the main application (obfuscated).
    • Runtime (in main app):
      • Attempt to read the .dylib file. This is very difficult due to LD_PRELOAD interception. May require low-level system calls (syscall) – risky and unreliable.
      • If read successfully, calculate SHA-256 hash.
      • Compare to stored hash.
      • If mismatch, take action (error, terminate, report).
  2. Obfuscation: Obfuscate the hash check code.
  3. Anti-Debugging: Implement in both main app and preloaded library.

  • Threats Mitigated:

    • Malicious Library Replacement (Severity: Critical): Detects replacement with a malicious library.
    • Tampering with the Preloaded Library (Severity: Critical): Detects modification of the library.

  • Impact:

    • Limited protection against replacement/tampering. Not foolproof due to LD_PRELOAD interference. Increases attacker difficulty.

  • Currently Implemented: (Example)

    • None specifically targeting the preloaded library.

  • Missing Implementation: (Example)

    • Hashing and runtime verification of the .dylib.
    • Obfuscation of integrity checks.
    • Anti-debugging.

Mitigation Strategy: Avoid Sensitive Operations within the Preloaded Library

  1. Identify Sensitive Operations: List operations with sensitive data/actions (crypto keys, credentials, sensitive network requests, protected resources).
  2. Minimize Preloaded Library Involvement: Design the app so these operations are in the main application code, not the preloaded library.
  3. Secure Communication: If the library must interact with sensitive data, use secure communication (encryption, integrity checks). Be aware of LD_PRELOAD interception.
  4. Data Minimization: Pass only the absolute minimum data to the library.

  • Threats Mitigated:

    • Information Disclosure (Severity: High/Critical): Reduces risk of exposure if the library is compromised.
    • Unauthorized Access (Severity: High/Critical): Reduces risk of unauthorized actions if the library is compromised.

  • Impact:

    • Significantly reduces impact of a compromised library by limiting access to sensitive data/operations.

  • Currently Implemented: (Example)

    • Some effort may exist to keep sensitive operations in the main app.

  • Missing Implementation: (Example)

    • Formal review/documentation of sensitive operations.
    • Systematic minimization of library involvement.
    • Secure communication (if needed).

Mitigation Strategy: Regular Updates and Audits (of the preloaded library)

  1. Establish Update Schedule: Define a regular schedule for reviewing and updating the preloaded library's code.
  2. Code Review: During each update, conduct a thorough code review, focusing on changes and new vulnerabilities.
  3. Security Audits: Periodically conduct a comprehensive security audit of the entire application, especially the preloaded library, by an independent expert.
  4. Vulnerability Monitoring: Stay informed about vulnerabilities related to swift-on-ios, LD_PRELOAD, and related technologies.
  5. Patching: Promptly apply patches/updates for vulnerabilities.

  • Threats Mitigated:

    • All threats from previous strategies (Severity: Varies): Addresses vulnerabilities discovered after deployment.

  • Impact:

    • Maintains security over time by addressing new vulnerabilities.

  • Currently Implemented: (Example)

    • Ad-hoc updates when issues are reported.

  • Missing Implementation: (Example)

    • Formal update schedule.
    • Regular code reviews and independent security audits.
    • Proactive vulnerability monitoring.