#MacOS

  1. VPNStatus, a replacement for macOS builtin VPN Status

    In this post I present VPNStatus, an application that replicates some functionalities of macOS built-in VPN status menu: list the VPN services and their status connect to a VPN service disconnect from a VPN service possibility to auto connect to a VPN service if the application is running This application also allows to auto connect to an IKEv2 VPN service, something that is currently not possible on macOS.
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  2. macOS VPN architecture from System Preferences down to nesessionmanager

    macOS 10.13 contains a built-in VPN client that natively supports L2TP over IPSec as well as IKEv2. In this post I describe some parts of the internal architecture of the macOS VPN client. This information will be used in a following article to build an application that replicates some functionalities of the VPN status in the menu bar. This application will also allow to auto connect to an IKEv2 VPN service, something that is currently not possible on macOS.
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  3. Apple’s use of Swift in iOS 11.1 and macOS 10.13.1

    A year ago I analyzed how many built-in apps in iOS 10.1 and macOS 10.12 were using Swift: Apple’s use of Swift in iOS 10.1 and macOS 10.12. How many built-in apps are using Swift in iOS 11.1 and macOS 10.13.1? Let’s find it out! Tool to detect binaries using Swift Last year I explained how to write a script that loops through all the files of a folder and print the paths of binaries using Swift.
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  4. Swift: Banning force unwrapping optionals

    Swift Optionals and force unwrapping The Swift programming language supports optional types, which handle the absence of a value. An optional represents two possibilities: Either there is a value and you can unwrap the optional to access that value, or there isn’t a value at all. Here is how you can declare an optional variable in Swift: var myOptionalString: String? The myOptionalString variable can contain a string value or nil.
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  5. Testing if an arbitrary pointer is a valid Objective-C object

    Let’s say you pick a random pointer. Can we know if it points to a valid Objective-C object? Of course without crashing… Well there is no simple solution. In this post I give a solution for 64-bit architectures. The code provided has only been tested on macOS 10.12.1 and iOS 10.1.1 with the modern Objective-C runtime. There is not much documentation available on this subject. There is one article written in 2010 by Matt Gallagher but the content is outdated and not working properly anymore.
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  6. Apple’s use of Swift in iOS 10.1 and macOS 10.12

    Swift has been announced at the WWDC 2014, more than 2 years ago. Most of the sample code projects from Apple are now written in Swift. But does Apple use Swift in iOS 10.1 and macOS 10.12.1? How to detect if a binary is using Swift? A naïve approach would be to check if an app contains the Swift libraries in its Frameworks folder: libswiftCore.dylib, libswiftFoundation.dylib, … Here is the content of the Frameworks folder of the MRT.
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  7. Dump decrypted mach-o apps

    In a previous post CryptedHelloWorld: App with encrypted mach-o sections, I created a simple macOS app CryptedHelloWorld with its (__TEXT, __text) section encrypted. The section is decrypted by a constructor function. This post explains how to dump the decrypted app. A common way is to attach the app with a debugger (GDB, LLDB) and manually dump the decrypted memory to disk. However I will use a different solution by using 2 techniques already presented in previous posts: a destructor function and code injection.
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  8. Mail.app plugin compatibility for macOS Sierra (10.12)

    Mail.app in macOS 10.11 and earlier used to check the plugins compatibility using the SupportedPluginCompatibilityUUIDs key in the plugin’s Info.plist. For example a Mail plugin would only be compatible with macOS 10.11.6 if its Info.plist contained the following: <key>SupportedPluginCompatibilityUUIDs</key> <array> <string>71562B89-0D90-4588-8E94-A75B701D6443</string> </array> Mail.app version 10.0 in macOS Sierra (10.12) now uses a different key to check the plugins compatibility. It now requires a key with the format Supported%ld.%ldPluginCompatibilityUUIDs where %ld.
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  9. CryptedHelloWorld: App with encrypted mach-o sections

    In a previous post ( constructor and destructor attributes ), I described the constructor attribute and mentioned software protection as a possible use case: A constructor attribute could be used to implement a software protection. You could encrypt your executable with a custom encryption and use a constructor function to decrypt the binary just before it is loaded. In this post I describe such a protection with an example.
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  10. constructor and destructor attributes

    GCC (and Clang) supports constructor and destructor attributes: __attribute__((constructor)) __attribute__((destructor)) Description A function marked with the __attribute__((constructor)) attribute will be called automatically before your main() function is called. Similarly a function marked with the __attribute__((destructor)) attribute will be called automatically after your main() function returns. You can find the GCC documentation here: constructor destructor The constructor attribute causes the function to be called automatically before execution enters main ().
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