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MASVS v1 MSTG-CODE-9
MASVS v2 MASVS-CODE-4
Last updated: February 16, 2024

Make Sure That Free Security Features Are Activated

Overview

Static Analysis

You can use radare2 to check the binary security features.

Let's use the Damn Vulnerable iOS App DVIA v1 as an example. Open its main binary with radare2:

r2 DamnVulnerableIOSApp

And run the following commands:

[0x1000180c8]> i~pic,canary
canary   true
pic      true

[0x1000180c8]> is~release,retain
124  0x002951e0 0x1000891e0 LOCAL  FUNC 0        imp.dispatch_release
149  0x00294e80 0x100088e80 LOCAL  FUNC 0        imp.objc_autorelease
150  0x00294e8c 0x100088e8c LOCAL  FUNC 0        imp.objc_autoreleasePoolPop
151  0x00294e98 0x100088e98 LOCAL  FUNC 0        imp.objc_autoreleasePoolPush
152  0x00294ea4 0x100088ea4 LOCAL  FUNC 0        imp.objc_autoreleaseReturnValue
165  0x00294f40 0x100088f40 LOCAL  FUNC 0        imp.objc_release
167  0x00294f58 0x100088f58 LOCAL  FUNC 0        imp.objc_retainAutorelease
168  0x00294f64 0x100088f64 LOCAL  FUNC 0        imp.objc_retainAutoreleaseReturnValue
169  0x00294f70 0x100088f70 LOCAL  FUNC 0        imp.objc_retainAutoreleasedReturnValue

All the features are enabled in these examples:

  • PIE (Position Independent Executable): indicated by the flag pic true.

    • Applies to all apps independently of the language used.
    • Applies only to the main executable (MH_EXECUTE), not to dynamic libraries (MH_DYLIB).

  • Stack Canary: indicated by the flag canary true.

    • Applies to apps containing Objective-C code.
    • Not necessarily required for pure Swift apps (Swift is memory safe by design).
    • Especially important for apps containing C/C++ code, as they provide direct access to memory and pointers, making them more vulnerable to buffer overflows.

  • ARC (Automatic Reference Counting): indicated by symbols such as objc_autorelease or objc_retainAutorelease.

    • Important for binaries containing Objective-C code.
    • For binaries written purely in Swift, ARC is enabled by default.
    • ARC is not relevant for binaries written purely in C/C++, as it's a memory management feature specific to Objective-C and Swift.

Dynamic Analysis

These checks can be performed dynamically using objection. Here's one example:

com.yourcompany.PPClient on (iPhone: 13.2.3) [usb] # ios info binary
Name                  Type     Encrypted    PIE    ARC    Canary    Stack Exec    RootSafe
--------------------  -------  -----------  -----  -----  --------  ------------  ----------
PayPal                execute  True         True   True   True      False         False
CardinalMobile        dylib    False        False  True   True      False         False
FraudForce            dylib    False        False  True   True      False         False
...

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