Obfuscate Mobile Business Logic, Anti-Reversing in Android Apps

Last updated January 8, 2024 by Appdome

Learn to Obfuscate App Logic in Android apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

What is code obfuscation?

One of the most used types of reverse engineering is static code analysis, where an attacker attempts to analyze the source code of an iOS or Android application in order to understand what the source code does and how it does it – all without running the app.

While there are many different methods and techniques to obfuscate mobile application code, Obfuscating App Logic is an effective way of preventing attackers from using static code analysis to understand the application’s logical flow, especially when combined with other obfuscation techniques such as binary code obfuscation and application shielding.

How does Appdome implement code obfuscation?

Appdome’s Obfuscate App Logic, when enabled, automatically obfuscates application logic classes and methods, renaming them to random strings. This solution preserves the clarity of open-source libraries by keeping them non-obfuscated. The advanced combination of this feature with string encryption and Strip Debug Information, significantly complicates unauthorized attempts to understand the code.

When enabling Appdome’s Obfuscate App Logic feature, the obfuscation of package names and dynamic classes, are included automatically. This functionality simplifies the process, making it seamless to incorporate robust code protection without necessitating manual adjustments for these components.

Detailed Features of Appdome’s Code Obfuscation:

  • Excluding Specific Classes:
    Excluding a class from obfuscation necessitates the exclusion of the whole package to which the class belongs. This is due to the access rules inherent to Java classes.
    In the process of obfuscating a package, Appdome changes it entirely. However, any excluded classes still retain the non-obfuscated package name. Therefore, when an obfuscated class tries to access a non-obfuscated class (the excluded one), Java may raise an ‘illegal access exception’ despite both classes residing under the same package name in the original non-obfuscated app.
    To prevent such cases, once a class is excluded, the class package is excluded.
    In order to exclude classes, you will need to add the package of the classes you wish to exclude. For instance, excluding the class “com/appdome/test/TestClass” involves adding either “com/appdome/test” or “com.appdome.test” to the Exclude Specific Classes list.
  • Multilingual Obfuscation:
    When using only ASCII characters for obfuscation, it is easier to follow a flow using reverse engineering tools such as JADX or hooking methods using hacking tools such as Frida. Appdome’s new obfuscation mechanism, Multilingual Obfuscation adds another layer of protection to the app’s obfuscation, significantly complicating any attempts made by an attacker to reverse engineer the application and deconstruct the code, thereby enhancing its security.  Appdome’s Multilingual Obfuscation method, differs from standard methods in that it uses Unicode characters, and a novel runtime algorithm as opposed to traditional ASCII characters, this complexity significantly complicates attempts to deconstruct the code, thereby enhancing its security.

Note: The Multilingual Obfuscation feature is supported on Android 8.0 and above. Please be aware that if the app is obfuscated using Unicode characters, you will not be able to install this app on Android 7.1.1 or earlier versions.

Prerequisites for Using Obfuscate App Logic:

To use Appdome’s mobile app security build system to Obfuscate App Logic , you’ll need:

Obfuscate App Logic on Android apps using Appdome

On Appdome, follow these 3 simple steps to create self-defending Android Apps that Obfuscate App Logic 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. Android Formats: .apk or .aab
    4. Obfuscate App Logic Compatible With: Java, JS, C++, C#, Kotlin, Flutter, React Native, Unity, Xamarin, Cordova and other Android apps
  2. Build the feature: Obfuscate App Logic.

    1. Building Obfuscate App Logic by using Appdome’s DEV-API:

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

        Figure 1: Fusion Set that will contain the Obfuscate App Logic 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 Obfuscate App Logic feature via Appdome Console, to add the Obfuscate App Logic 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 Obfuscate App Logic feature via Appdome Console

      To build the Obfuscate App Logic 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 Obfuscate App Logic you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Obfuscate App Logic

        Fusion Set applied Obfuscate App Logic

        Figure 4: Fusion Set that displays the newly added Obfuscate App Logic protection

      3. Optional Configuration with Obfuscate App Logic:
        1. Obfuscate Package Names

          Obfuscates package and class names within the application’s business logic.

        2. Obfuscate Dynamic Classes

          Obfuscates (renames) classes to random strings.

        3. Obfuscate Dynamic Methods

          Obfuscates (renames) methods to random strings.

        4. Obfuscate Linkages and Reflection

          Supports obfuscation of classes and methods used in reflection and in JNI up-calls and down-calls.

        5. Obfuscate Crashes

          Obfuscates methods and classes in crashes and stack traces.

        6. Exclude Specific Classes

          List class or package prefixes to exclude from obfuscation.

        7. Obfuscation Mapping File/Script

          Download mapping scripts and files in order to deobfuscate the app for further investigation.

        8. Multilingual Obfuscation

          Employs Unicode and unique algorithms, complicating reverse engineering attempts beyond standard ASCII obfuscation methods.

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

Using Threat-Events™ for App Logic Intelligence and Control in Android Apps

Appdome Threat-Events™ provides consumable in-app mobile app attack intelligence and defense control when App Logic is detected. To consume and use Threat-Events™ for App Logic in Android Apps, use registerReceiver in the Application OnCreate, and the code samples for Threat-Events™ for App Logic shown below.

The specifications and options for Threat-Events™ for App Logic are:

Threat-Event™ Elements Obfuscate App Logic Method Detail
Appdome Feature Name Obfuscate App Logic
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
Visible in ThreatScope™
Developer Parameters for Obfuscating App Logic Threat-Event™
Threat-Event NAME NoName
Threat-Event DATA reasonData
Threat-Event CODE reasonCode
Threat-Event REF 6801
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), Android developers can get detailed attack intelligence and granular defense control in Android applications and create amazing user experiences for all mobile end users when App Logic is detected.

The following is a code sample for native Android apps, which uses all values in the specification above for Obfuscate App Logic:

Using Appdome, there are no development or coding prerequisites to build secured Android Apps by using Obfuscate App Logic. 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 Obfuscate App Logic

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.

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