Binary Code Obfuscation, Anti-Reversing - Android & iOS

Last updated November 29, 2023 by Appdome

Learn to Prevent Code Obfuscation in Mobile apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

Why is Obfuscation Efficient Against Reverse Engineering?

Decompilers have reached a maturity level that allows them to easily recover source code from mobile apps. Binary code obfuscation proved itself as an efficient first line of defense against reverse engineering attempts by hackers. What sets various obfuscation solutions apart is several things: (1) Ease of use (specialized compilers to post-build tools), (2) Performance (some obfuscation methods might impose a performance penalty), and (3) the reference threat level (expertise and time needed to break the defense).

How does Appdome Implement Binary Code Obfuscation?

In iOS, the application’s executable manifests as binary code. Appdome shuffles the code around, so that when the reverse engineering tool attempts to determine the target of a reference, it will appear as though it points to some arbitrary location. On a large scale, this renders the code completely unintelligible. However, the application must contain enough binary code to make the shuffling effective, otherwise it is advisable to use Appdome Flow Relocation as an alternative.

In Android, shared-libraries constitute the native-code part of the app. Appdome uses the loading mechanism of shared libraries in Android and modifies it so encrypted libraries can be loaded. Then, when integrating Binary Code Obfuscation, the native libraries that come with the application get encrypted by using a unique key.

When an attacker attempts to open the protected libraries in a reverse engineering tool, the applications will fail at recognizing the file as binary code.

Prerequisites for Using Binary Code Obfuscation:

To use Appdome’s mobile app security build system to Prevent Code Obfuscation , you’ll need:

Prevent Code Obfuscation on Mobile apps using Appdome

On Appdome, follow these 3 simple steps to create self-defending Mobile Apps that Prevent Code Obfuscation 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. Mobile App Formats: .ipa for iOS, or .apk or .aab for Android
    4. Binary Code Obfuscation Compatible With: Obj-C, Java, JS, C#, C++, Swift, Kotlin, Flutter, React Native, Unity, Xamarin, and more
  2. Build the feature: Binary Code Obfuscation.

    1. Building Binary Code Obfuscation by using Appdome’s DEV-API:

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

        Figure 1: Fusion Set that will contain the Binary Code Obfuscation 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 Binary Code Obfuscation feature via Appdome Console, to add the Binary Code Obfuscation 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 Binary Code Obfuscation feature via Appdome Console

      To build the Binary Code Obfuscation 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 Binary Code Obfuscation you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Binary Code Obfuscation

        Fusion Set applied Binary Code Obfuscation

        Figure 4: Fusion Set that displays the newly added Binary Code Obfuscation protection

      3. Extra Configuration with Binary Code Obfuscation:
        1. Favor App’s Size

          Automatically detect and exclude publicly available elements from being obfuscated, to reduce overall application package size.

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

Using Threat-Events™ for Code Obfuscation Intelligence and Control in Mobile Apps

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

The specifications and options for Threat-Events™ for Code Obfuscation are:

Threat-Event™ Elements Prevent Code Obfuscation Method Detail
Appdome Feature Name Binary Code Obfuscation
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 Preventing Code Obfuscation 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
deviceBrand Brand of the device
deviceBoard Board of the device
buildUser Build user
buildHost Build host
sdkVersion Sdk version
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), Mobile developers can get detailed attack intelligence and granular defense control in Mobile applications and create amazing user experiences for all mobile end users when Code Obfuscation is detected.

The following is a code sample for native Mobile apps, which uses all values in the specification above for Binary Code Obfuscation:


Using Appdome, there are no development or coding prerequisites to build secured Mobile Apps by using Binary Code Obfuscation. 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 Binary Code Obfuscation

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:

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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