Overview

This test case checks if [ARC (Automatic Reference Counting)](../../../Document/0x04h-Testing-Code-Quality.md#automatic-reference-counting) is enabled in iOS apps. ARC is a compiler feature in Objective-C and Swift that automates memory management, reducing the likelihood of memory leaks and other related issues. Enabling ARC is crucial for maintaining the security and stability of iOS applications.

When ARC is enabled, binaries will include symbols such as objc_autorelease or objc_retainAutorelease.

Steps

  1. Use MASTG-TECH-0082 to identify all bundled libraries.
  2. Use MASTG-TECH-0118 on the main binary and each shared library to obtain all relevant artifacts related to the compiler-provided security features.

Observation

The output should contain a list of symbols of the main binary and each shared library.

Evaluation

The test case fails if any binary or library containing Objective-C or Swift code is missing ARC-related symbols. The presence of symbols such as _objc_msgSend (Objective-C) or _swift_allocObject (Swift) without corresponding ARC symbols indicates that ARC may not be enabled.

Note

Checking for these symbols only indicates that ARC is enabled somewhere in the app. While ARC is typically enabled or disabled for the entire binary, there can be corner cases where only parts of the application or libraries are protected. For example, if the app developer statically links a library that has ARC enabled, but disables it for the entire application.

If you want to be sure that specific security-critical methods are adequately protected, you need to reverse-engineer each of them and manually check for ARC, or request the source code from the developer.