How to Block Resigning and Repackaging Android & iOS Apps

Last updated May 21, 2023 by Appdome

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

What is Tampering?

To ensure your app is protected against unauthorized changes or any modification that can compromise them is critical. Some examples are:

Repackaging the app
Resigning the application
Modifying the application’s executable
- iOS: Main executable (see structure of an iOS application)
- Android: DEX files (see structure of an Android application)
Attempting to Modify the Appdome adapter
Moving the application’s sandbox under the name of a different package

Why Prevent Tampering in Android Apps?

Tamper prevention protects your app against unwanted changes, mods, and hacks that can negative impact or compromise your mobile business application including financial and data loss, intelectual, privacy & repetitional damage. Appdome prevents all this without adding development work or time to your release cycles. This is done by sealing your app and actively detecting modifications during initialization and at multiple other points during run-time.

Prevent Tampering on Android apps using Appdome

On Appdome, follow these 3 simple steps to create self-defending Android Apps that Prevent Tampering without an SDK or gateway:

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. Anti-Tampering Compatible With: Java, JS, C++, C#, Kotlin, Flutter, React Native, Unity, Xamarin, Cordova and more
Build the feature: Anti-Tampering.
1. Building Anti-Tampering by using Appdome’s DEV-API:
  1. Create and name the Fusion Set (security template) that will contain the Anti-Tampering feature as shown below:
  2. Follow the steps in Sections 2.2.1-2.2.2 of this article, Building the Anti-Tampering feature via Appdome Console, to add the Anti-Tampering feature to this Fusion Set.
  3. 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):
    
    Figure 2: Fusion Set Detail Summary
    Note: Annotating the Fusion Set to identify the protection(s) selected is optional only (not mandatory).
  4. 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, Cirlce CI or other system:
    
    Build an API for the app – for instructions, see the tasks under Appdome API Reference Guide
    
    Look for sample APIs in Appdome’s GitHub Repository
2. Building the Anti-Tampering feature via Appdome Console
  
  To build the Anti-Tampering protection by using Appdome Console, follow the instructions below.
  1. Where: Inside the Appdome Console, go to Build > Security Tab > ONEShield™ section . Like all other options in ONEShield™, Anti-Tampering is turned on by default, as shown below:
    Figure 3: Anti-Tampering option
    Note: The App Compromise Notification contains an easy to follow default remediation path for the mobile app end user. You can customize this message as required to achieve brand specific support, workflow or other messaging.
  2. When you select the Anti-Tampering you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Anti-Tampering
    
    Figure 4: Fusion Set that displays the newly added Anti-Tampering protection
  3. Select the Threat-Event™ in-app mobile Threat Defense and Intelligence policy for Anti-Tampering:
    
    Threat-Events™ OFF > In-App Defense
    If the Threat-Events™ setting is cleared (not selected). Appdome will detect and defend the user and app by enforcing Prevent Tampering.
    
    Threat-Events™ ON > In-App Detection
    When this setting is used, Appdome detects tampering and passes Appdome’s Threat-Event™ attack intelligence to the app’s business logic for processing, enforcement, and user notification. For more information on consuming and using Appdome Threat-Events™ in the app, see section Using Threat-Events™ for Anti-Tampering Intelligence and Control in Mobile Apps.
    
    Threat-Events™ ON > In-App Defense
    When this setting is used, Appdome detects and defends against Tampering (same as Appdome Enforce) and passes Appdome’s Threat-Event™ attack intelligence the app’s business logic for processing. For more information on consuming and using Appdome Threat-Events™ in the app, see section Using Threat-Events™ for Anti-Tampering Intelligence and Control in Mobile Apps.
  4. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
Congratulations! The Anti-Tampering protection is now added to the mobile app
Certify the Anti-Tampering feature in Android Apps.

After building Anti-Tampering, Appdome generates a Certified Secure™ certificate to guarantee that the Anti-Tampering protection has been added and is protecting the app. To verify that the Anti-Tampering protection has been added to the mobile app, locate the protection in the Certified Secure™ certificate as shown below:

Figure 5: Certified Secure™ certificate

Each Certified Secure™ certificate provides DevOps and DevSecOps organizations the entire workflow summary, audit trail of each build, and proof of protection that Anti-Tampering has been added to each Android app. Certified Secure provides instant and in-line DevSecOps compliance certification that Anti-Tampering and other mobile app security features are in each build of the mobile app

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

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

The specifications and options for Threat-Events™ for Tampering are:

Threat-Event™ Elements	Prevent Tampering Method Detail
Appdome Feature Name	Anti-Tampering
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 Preventing Tampering Threat-Event™
Threat-Event NAME	AppIntegrityError
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 long
locationLat	Location lat
locationState	Location state
wifiSsid	Wifi SSID
wifiSsidPermissionStatus	Wifi SSID permission status
AntampIntegrityErrorMessage	Error message
data	Data related to the security event
certificateSHA1	Failed certificate

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 Tampering is detected.

The following is a code sample for native Android apps, which uses all values in the specification above for Anti-Tampering:

                    IntentFilter intentFilter = new IntentFilter();
                    intentFilter.addAction("AppIntegrityError");
                    BroadcastReceiver threatEventReceiver = new BroadcastReceiver() {
                        @Override
                        public void onReceive(Context context, Intent intent) {
                            String message = intent.getStringExtra("message"); // Message shown to the user
                            String reasonData = intent.getStringExtra("reasonData"); // Threat detection cause
                            String reasonCode = intent.getStringExtra("reasonCode"); // Event reason code
                            String currentThreatEventScore = intent.getStringExtra("currentThreatEventScore"); // Current threat event score
                            String threatEventsScore = intent.getStringExtra("threatEventsScore"); // Total threat events score
                            String variable = intent.getStringExtra(""); // Any other event specific context key

                            // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
                        }
                    };

                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
                        registerReceiver(threatEventReceiver, intentFilter, Context.RECEIVER_NOT_EXPORTED);
                    } else {
                        registerReceiver(threatEventReceiver, intentFilter);
                    }

Java
x
 
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("AppIntegrityError");
BroadcastReceiver threatEventReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        String message = intent.getStringExtra("message"); // Message shown to the user
        String reasonData = intent.getStringExtra("reasonData"); // Threat detection cause
        String reasonCode = intent.getStringExtra("reasonCode"); // Event reason code
        String currentThreatEventScore = intent.getStringExtra("currentThreatEventScore"); // Current threat event score
        String threatEventsScore = intent.getStringExtra("threatEventsScore"); // Total threat events score
        String variable = intent.getStringExtra("<Context Key>"); // Any other event specific context key
​
        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
    }
};
​
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
    registerReceiver(threatEventReceiver, intentFilter, Context.RECEIVER_NOT_EXPORTED);
} else {
    registerReceiver(threatEventReceiver, intentFilter);
}

                    val intentFilter = IntentFilter()
                    intentFilter.addAction("AppIntegrityError")
                    val threatEventReceiver = object : BroadcastReceiver() {
                        override fun onReceive(context: Context?, intent: Intent?) {
                            var message = intent?.getStringExtra("message") // Message shown to the user
                            var reasonData = intent?.getStringExtra("reasonData") // Threat detection cause
                            var reasonCode = intent?.getStringExtra("reasonCode") // Event reason code
                            var currentThreatEventScore = intent?.getStringExtra("currentThreatEventScore") // Current threat event score
                            var threatEventsScore = intent?.getStringExtra("threatEventsScore") // Total threat events score
                            var variable = intent?.getStringExtra("") // Any other event specific context key

                            // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
                        }
                    }

                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
                        registerReceiver(threatEventReceiver, intentFilter, Context.RECEIVER_NOT_EXPORTED)
                    } else {
                        registerReceiver(threatEventReceiver, intentFilter)
                    }

                         
                        Kotlin
                    
x
 
val intentFilter = IntentFilter()
intentFilter.addAction("AppIntegrityError")
val threatEventReceiver = object : BroadcastReceiver() {
    override fun onReceive(context: Context?, intent: Intent?) {
        var message = intent?.getStringExtra("message") // Message shown to the user
        var reasonData = intent?.getStringExtra("reasonData") // Threat detection cause
        var reasonCode = intent?.getStringExtra("reasonCode") // Event reason code
        var currentThreatEventScore = intent?.getStringExtra("currentThreatEventScore") // Current threat event score
        var threatEventsScore = intent?.getStringExtra("threatEventsScore") // Total threat events score
        var variable = intent?.getStringExtra("<Context Key>") // Any other event specific context key
​
        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
    }
}
​
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
    registerReceiver(threatEventReceiver, intentFilter, Context.RECEIVER_NOT_EXPORTED)
} else {
    registerReceiver(threatEventReceiver, intentFilter)
}

const { ADDevEvents } = NativeModules;
                const aDDevEvents = new NativeEventEmitter(ADDevEvents);

                function registerToDevEvent(action, callback) {
                    NativeModules.ADDevEvents.registerForDevEvent(action);
                    aDDevEvents.addListener(action, callback);
                }

                export function registerToAllEvents() {
                    registerToDevEvent(
                        "AppIntegrityError",
                        (userinfo) => Alert.alert(JSON.stringify(userinfo))

                        var message = userinfo["message"] // Message shown to the user
                        var reasonData = userinfo["reasonData"] // Threat detection cause
                        var reasonCode = userinfo["reasonCode"] // Event reason code
                        var currentThreatEventScore = userinfo["currentThreatEventScore"] // Current threat event score
                        var threatEventsScore = userinfo["threatEventsScore"] // Total threat events score
                        var variable = userinfo["<Context Key>"] // Any other event specific context key

                        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
                    );
                }

                     
                    React Native
                
​x
 
const { ADDevEvents } = NativeModules;
const aDDevEvents = new NativeEventEmitter(ADDevEvents);
​
function registerToDevEvent(action, callback) {
    NativeModules.ADDevEvents.registerForDevEvent(action);
    aDDevEvents.addListener(action, callback);
}
​
export function registerToAllEvents() {
    registerToDevEvent(
        "AppIntegrityError",
        (userinfo) => Alert.alert(JSON.stringify(userinfo))
​
        var message = userinfo["message"] // Message shown to the user
        var reasonData = userinfo["reasonData"] // Threat detection cause
        var reasonCode = userinfo["reasonCode"] // Event reason code
        var currentThreatEventScore = userinfo["currentThreatEventScore"] // Current threat event score
        var threatEventsScore = userinfo["threatEventsScore"] // Total threat events score
        var variable = userinfo["<Context Key>"] // Any other event specific context key
​
        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
    );
}
​

RegisterReceiver(new ThreatEventReceiver(), new IntentFilter("AppIntegrityError"));
                class ThreatEventReceiver : BroadcastReceiver
                {
                public override void OnReceive(Context context, Intent intent)
                {
                    String message = intent.getStringExtra("message"); // Message shown to the user
                    String reasonData = intent.getStringExtra("reasonData"); // Threat detection cause
                    String reasonCode = intent.getStringExtra("reasonCode"); // Event reason code
                    String currentThreatEventScore = intent.getStringExtra("currentThreatEventScore"); // Current threat event score
                    String threatEventsScore = intent.getStringExtra("threatEventsScore"); // Total threat events score
                    String variable = intent.getStringExtra("<Context Key>"); // Any other event specific context key

                    // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
                }
                }

                    
                    Xamarin/MAUI Android
                
​x
 
RegisterReceiver(new ThreatEventReceiver(), new IntentFilter("AppIntegrityError"));
​
class ThreatEventReceiver : BroadcastReceiver
{
  public override void OnReceive(Context context, Intent intent)
  {
    String message = intent.getStringExtra("message"); // Message shown to the user
    String reasonData = intent.getStringExtra("reasonData"); // Threat detection cause
    String reasonCode = intent.getStringExtra("reasonCode"); // Event reason code
    String currentThreatEventScore = intent.getStringExtra("currentThreatEventScore"); // Current threat event score
    String threatEventsScore = intent.getStringExtra("threatEventsScore"); // Total threat events score
    String variable = intent.getStringExtra("<Context Key>"); // Any other event specific context key
​
    // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
  }
}

                NSNotificationCenter.DefaultCenter.AddObserver(
                    (NSString)"JailbrokenDevice", // Threat-Event Identifier
                    delegate (NSNotification notification)
                    {
                        var message = notification.UserInfo.ObjectForKey("message"); // Message shown to the user
                        var reasonData = notification.UserInfo.ObjectForKey("reasonData"); // Threat detection cause
                        var reasonCode = notification.UserInfo.ObjectForKey("reasonCode"); // Event reason code
                        var currentThreatEventScore = notification.UserInfo.ObjectForKey("currentThreatEventScore"); // Current threat event score
                        var threatEventsScore = notification.UserInfo.ObjectForKey("threatEventsScore"); // Total threat events score
                        var variable = notification.UserInfo.ObjectForKey(""); // Any other event specific context key
                        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
                    });

                    
                    Xamarin/MAUI iOS
                
 
NSNotificationCenter.DefaultCenter.AddObserver(
  (NSString)"AppIntegrityError", // Threat-Event Identifier
  delegate (NSNotification notification)
  {
    var message = notification.UserInfo.ObjectForKey("message"); // Message shown to the user
    var reasonData = notification.UserInfo.ObjectForKey("reasonData"); // Threat detection cause
    var reasonCode = notification.UserInfo.ObjectForKey("reasonCode"); // Event reason code
    var currentThreatEventScore = notification.UserInfo.ObjectForKey("currentThreatEventScore"); // Current threat event score
    var threatEventsScore = notification.UserInfo.ObjectForKey("threatEventsScore"); // Total threat events score
    var variable = notification.UserInfo.ObjectForKey("<Context Keys>"); // Any other event specific context key
    // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
  });

window.broadcaster.addEventListener("AppIntegrityError", function(userInfo) {
        var message = userInfo.message // Message shown to the user
        var reasonData = userInfo.reasonData // Threat detection cause
        var reasonCode = userInfo.reasonCode // Event reason code
        var currentThreatEventScore = userInfo.currentThreatEventScore // Current threat event score
        var threatEventsScore = userInfo.threatEventsScore // Total threat events score
        var variable = userInfo.<Context Key> // Any other event specific context key

        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
            });

                    
                    Cordova
                
​x
 
window.broadcaster.addEventListener("AppIntegrityError", function(userInfo) {
        var message = userInfo.message // Message shown to the user
        var reasonData = userInfo.reasonData // Threat detection cause
        var reasonCode = userInfo.reasonCode // Event reason code
        var currentThreatEventScore = userInfo.currentThreatEventScore // Current threat event score
        var threatEventsScore = userInfo.threatEventsScore // Total threat events score
        var variable = userInfo.<Context Key> // Any other event specific context key
​
        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
});

Prerequisites to Using Anti-Tampering:

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

Appdome account (create a free Appdome account here)
A license for Anti-Tampering
Mobile App (.apk or .aab For Android)
Signing Credentials (see Signing Secure Android apps and Signing Secure iOS apps)

Using Appdome, there are no development or coding prerequisites to build secured Android Apps by using Anti-Tampering. 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 Anti-Tampering

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:

Customizing, Configuring & Branding Secure Mobile Apps
Deploying/Publishing Secure mobile apps to Public or Private app stores
Releasing Secured Android & iOS Apps built on Appdome.

All apps protected by Appdome are fully compatible with any public app store, including Apple App Store, Google Play, Huawei App Gallery and more.

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.

How to Block Resigning and Repackaging Android & iOS Apps

What is Tampering?

Why Prevent Tampering in Android Apps?

Prevent Tampering on Android apps using Appdome

Upload the Mobile App to Appdome.

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

Build the feature: Anti-Tampering.

Building Anti-Tampering by using Appdome’s DEV-API:

Building the Anti-Tampering feature via Appdome Console

Certify the Anti-Tampering feature in Android Apps.

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

Prerequisites to Using Anti-Tampering:

Related Articles:

Thank you!