Obfuscate iOS Control Flows & Methods, Anti-Reversing iOS Apps

Last updated November 29, 2023 by Appdome

Learn to Obfuscate code and control flows in iOS apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

What are Code and Control Flows?

Control flow is the order by which function calls, instructions, and statements are executed or evaluated when running a program. The control flow is a significant part of the logic of any computer program, as its implementation means that rather than just running any line of code sequentially, the developer determines what section of code is run in a program at any time. This allows implementing decision making, looping, and branching, so that specific blocks of code are executed only if they meet one or more conditions.

Code flow describes the path your code follows from starting point to a destination (final) point, in order to obtain the requested output. For example: getting a search query from a user, looking up the requested item in a list or a database, and displaying the search results.

Why do I Need to Obfuscate the Code and Control Flows?

Decompilers have reached a maturity level that allows recovering source code back from mobile apps with ease. Obfuscation is an established, widely used preventive measure against static reverse engineering attempts. Obfuscation proved to be an high performing, easy to use solution.

Appdome’s Flow Relocation modifies a mobile app’s compiled code by relocating and obfuscating the app’s code flow and logical control-flow.  In so doing, Appdome makes reverse engineering much harder to perform while preserving the functionality and performance of the original app.

Prerequisites for Using Flow Relocation:

To use Appdome’s mobile app security build system to Obfuscate code and control flows , you’ll need:

Obfuscate code and control flows on iOS apps using Appdome

On Appdome, follow these 3 simple steps to create self-defending iOS Apps that Obfuscate code and control flows without an SDK or gateway:

  1. Upload the Mobile App to Appdome.

    1. Upload an app to Appdome’s Mobile App Security Build System

    2. Upload Method: Appdome Console or DEV-API
    3. iOS Formats: .ipa
    4. Flow Relocation Compatible With: Obj-C, Java, Swift, Flutter, React Native, Unity, Xamarin, Cordova and more
  2. Build the feature: Flow Relocation.

    1. Building Flow Relocation by using Appdome’s DEV-API:

      1. Create and name the Fusion Set (security template) that will contain the Flow Relocation feature as shown below:
      2. fusion set that contains Flow Relocation

        Figure 1: Fusion Set that will contain the Flow Relocation feature
        Note: Naming the Fusion Set to correspond to the protection(s) selected is for illustration purposes only (not required).

      3. Follow the steps in Sections 2.2.1-2.2.2 of this article, Building the Flow Relocation feature via Appdome Console, to add the Flow Relocation feature to this Fusion Set.

      4. Open the Fusion Set Detail Summary by clicking the “...” symbol on the far-right corner of the Fusion Set, as shown in Figure 1 above, and get the Fusion Set ID from the Fusion Set Detail Summary (as shown below): fusion Set Detail Summary image

        Figure 2: Fusion Set Detail Summary
        Note: Annotating the Fusion Set to identify the protection(s) selected is optional only (not mandatory).

      5. Follow the instructions below to use the Fusion Set ID inside any standard mobile DevOps or CI/CD toolkit like Bitrise, App Center, Jenkins, Travis, Team City, Circle CI or other system:
        1. Build an API for the app – for instructions, see the tasks under Appdome API Reference Guide
        2. Look for sample APIs in Appdome’s GitHub Repository
    2. Building the Flow Relocation feature via Appdome Console

      To build the Flow Relocation protection by using Appdome Console, follow the instructions below.

      1. Where: Inside the Appdome Console, go to Build > Security Tab > TOTALCode™ Obfuscation section.
      2. When you select the Flow Relocation you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Flow Relocation

        Fusion Set applied Flow Relocation

        Figure 4: Fusion Set that displays the newly added Flow Relocation protection

      3. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
    Congratulations!  The Flow Relocation protection is now added to the mobile app

Using Threat-Events™ for code and control flows Intelligence and Control in iOS Apps

Appdome Threat-Events™ provides consumable in-app mobile app attack intelligence and defense control when code and control flows are detected. To consume and use Threat-Events™ for code and control flows in iOS Apps, use AddObserverForName in Notification Center, and the code samples for Threat-Events™ for code and control flows shown below.

The specifications and options for Threat-Events™ for code and control flows are:

Threat-Event™ Elements Obfuscate code and control flows Method Detail
Appdome Feature Name Flow Relocation
Threat-Event Mode
OFF, IN-APP DEFENSE Appdome detects, defends and notifies user (standard OS dialog) using customizable messaging.
ON, IN-APP DETECTION Appdome detects the attack or threat and passes the event in a standard format to the app for processing (app chooses how and when to enforce).
ON, IN-APP DEFENSE Uses Appdome Enforce mode for any attack or threat and passes the event in a standard format to the app for processing (gather intel on attacks and threats without losing any protection).
Certified Secure™ Threat Event Check x
Visible in ThreatScope™ x
Developer Parameters for Obfuscating code and control flows Threat-Event™
Threat-Event NAME
Threat-Event DATA reasonData
Threat-Event CODE reasonCode
Threat-Event REF
Threat-Event SCORE
currentThreatEventScore Current Threat-Event score
threatEventsScore Total Threat-events score
Threat-Event Context Keys
message Message displayed for the user on event
externalID The external ID of the event which can be listened via Threat Events
osVersion OS version of the current device
deviceModel Current device model
deviceManufacturer The manufacturer of the current device
fusedAppToken The task ID of the Appdome fusion of the currently running app
kernelInfo Info about the kernel: system name, node name, release, version and machine.
carrierPlmn PLMN of the device
deviceID Current device ID
reasonCode Reason code of the occured event
buildDate Appdome fusion date of the current application
devicePlatform OS name of the current device
carrierName Carrier name of the current device
updatedOSVersion Is the OS version up to date
timeZone Time zone
deviceFaceDown Is the device face down
locationLong Location longitude conditioned by location permission
locationLat Location latitude conditioned by location permission
locationState Location state conditioned by location permission
wifiSsid Wifi SSID
wifiSsidPermissionStatus Wifi SSID permission status

With Threat-Events™ enabled (turned ON), iOS developers can get detailed attack intelligence and granular defense control in iOS applications and create amazing user experiences for all mobile end users when code and control flows are detected.

The following is a code sample for native iOS apps, which uses all values in the specification above for Flow Relocation:

Using Appdome, there are no development or coding prerequisites to build secured iOS Apps by using Flow Relocation. There is no SDK and no library to code or implement in the app and no gateway to deploy in your network. All protections are built into each app and the resulting app is self-defending and self-protecting.

Releasing and Publishing Mobile Apps with Flow Relocation

After successfully securing your app by using Appdome, there are several available options to complete your project, depending on your app lifecycle or workflow. These include:

Related Articles:

How to Obfuscate Non-Native Android & iOS Code and Frameworks

How to add Native Code Obfuscation to any iOS, Android app

How to Encrypt Java Class Files (.dex) in Android Apps

Appdome ONEShield Mobile App Hardening

If you have any questions, please send them our way at support.appdome.com or via the chat window on the Appdome platform.

Thank you!

Thanks for visiting Appdome! Our mission is to secure every app on the planet by making mobile app security easy. We hope we’re living up to the mission with your project.

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