How to Prevent Fake iOS Apps Using Signature Validation

Last updated September 21, 2023 by Appdome

Learn to Validate App Store Signature Validation in iOS apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

Why Should Developers Prevent the Running of non-authorized apps?

Fraudsters and other cyber-criminals often use various methods and techniques to create fake apps by copying or cloning existing popular apps and then repackaging, re-signing, and re-distributing those apps on alternative, malicious or non-approved app stores. It is fairly easy for malicious actors to publish fake, malicious or pirated apps on app stores other than Apple’s App Store. They only need to download a target app (such as your app) on a Jailbroken mobile device, modify the app, and then repackage, re-sign, and re-distribute the fake or pirated mobile app to any app store they want.

For additional information, see Top Reasons Cyber-criminals Publish Mobile Apps on Alternative App Stores.

How does Appdome Prevent the Running of non-Authorized Apps?

Appdome App Store Validation validates that apps signed for Apple App Store cannot be distributed through any other app stores. If the original app was signed for Apple’s App Store, Appdome prevents the app from being re-signed with a different application identifier. If the app was originally published to the app store, and the application identifier is different than the originally signed app, Appdome detects the difference and prevents the app from running.

Validate App Store Signature Validation on iOS apps using Appdome

On Appdome, follow these 3 simple steps to create self-defending iOS Apps that Validate App Store Signature Validation 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. iOS Formats: .ipa
4. App Store Signature Validation Compatible With: Obj-C, C+, Java, Swift, Flutter, React Native, Unity, Xamarin, Cordova and more
Build the feature: App Store Signature Validation.
1. Building App Store Signature Validation by using Appdome’s DEV-API:
  1. Create and name the Fusion Set (security template) that will contain the App Store Signature Validation feature as shown below:
  2. Follow the steps in Sections 2.2.1-2.2.2 of this article, Building the App Store Signature Validation feature via Appdome Console, to add the App Store Signature Validation 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 App Store Signature Validation feature via Appdome Console
  
  To build the App Store Signature Validation protection by using Appdome Console, follow the instructions below.
  1. Where: Inside the Appdome Console, go to Build > Anti Fraud Tab > Mobile Cheat Prevention section
  2. How: Toggle (turn ON) App Store Signature Validation, as shown below.
    If needed, Customize the Threat Notification to be displayed to the mobile end-user in a standard OS dialog notification when Appdome Validates App Store Signature Validation.
    
    Figure 3: Validate App Store Signature Validation 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.
  3. When you select the App Store Signature Validation you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains App Store Signature Validation
    
    Figure 4: Fusion Set that displays the newly added App Store Signature Validation protection
  4. Select the Threat-Event™ in-app mobile Threat Defense and Intelligence policy for App Store Signature Validation:
    
    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 Validate App Store Signature Validation.
    
    Threat-Events™ ON > In-App Detection
    When this setting is used, Appdome detects an attempt to install an app from a non-official App Store. 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 App Store Signature Validation Intelligence and Control in Mobile Apps.
    
    Threat-Events™ ON > In-App Defense
    When this setting is used, Appdome detects and defends against App Store Signature Validation (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 App Store Signature Validation Intelligence and Control in Mobile Apps.
  5. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
Congratulations! The App Store Signature Validation protection is now added to the mobile app
Certify the App Store Signature Validation feature in iOS Apps.

After building App Store Signature Validation, Appdome generates a Certified Secure™ certificate to guarantee that the App Store Signature Validation protection has been added and is protecting the app. To verify that the App Store Signature Validation 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 App Store Signature Validation has been added to each iOS app. Certified Secure provides instant and in-line DevSecOps compliance certification that App Store Signature Validation and other mobile app security features are in each build of the mobile app

Using Threat-Events™ for App Store Signature Validation Intelligence and Control in iOS Apps

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

The specifications and options for Threat-Events™ for App Store Signature Validation are:

Threat-Event™ Elements	Validate App Store Signature Validation Method Detail
Appdome Feature Name	App Store Signature Validation
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 Validating App Store Signature Validation Threat-Event™
Threat-Event NAME	This app cannot be installed from unofficial app stores. For your protection, the app will close. Please contact support
Threat-Event DATA	reasonData
Threat-Event CODE	reasonCode
Threat-Event REF	6902
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 long
locationLat	Location lat
locationState	Location state
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 App Store Signature Validation is detected.

The following is a code sample for native iOS apps, which uses all values in the specification above for App Store Signature Validation:

let center = NotificationCenter.default
                center.addObserver(forName: Notification.Name("This app cannot be installed from unofficial app stores. For your protection, the app will close. Please contact support"), object: nil, queue: nil) { (note) in
                    guard let usrInf = note.userInfo else {
                        return
                    }

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

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

                         
                        Swift
                    
​x
 
let center = NotificationCenter.default
center.addObserver(forName: Notification.Name("This app cannot be installed from unofficial app stores. For your protection, the app will close. Please contact support"), object: nil, queue: nil) { (note) in
    guard let usrInf = note.userInfo else {
        return
    }
​
    let message = usrInf["message"]; // Message shown to the user
    let reasonData = usrInf["reasonData"]; // Threat detection cause
    let reasonCode = usrInf["reasonCode"]; // Event reason code
    let currentThreatEventScore = usrInf["currentThreatEventScore"]; // Current threat event score
    let threatEventsScore = usrInf["threatEventsScore"]; // Total threat events score
    let variable = usrInf["<Context Key>"]; // Any other event specific context key
​
    // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
}

[[NSNotificationCenter defaultCenter] addObserverForName:  "This app cannot be installed from unofficial app stores. For your protection, the app will close. Please contact support" object:nil queue:nil usingBlock:^(NSNotification *org_note) {
                    __block NSNotification *note = org_note;
                    dispatch_async(dispatch_get_main_queue(), ^(void) {
                        var threatEventsScore = intent.getStringExtra("threatEventsScore")
                        NSString *message = [[note userInfo] objectForKey:@"message"]; // Message shown to the user
                        NSString *reasonData = [[note userInfo] objectForKey:@"reasonData"]; // Threat detection cause
                        NSString *reasonCode = [[note userInfo] objectForKey:@"reasonCode"]; // Event reason code
                        NSString *currentThreatEventScore = [[note userInfo] objectForKey:@"currentThreatEventScore"]; // Current threat event score
                        NSString *threatEventsScore = [[note userInfo] objectForKey:@"threatEventsScore"]; // Total threat events score
                        NSString *variable = [[note userInfo] objectForKey:@"<Context Key>"]; // Any other event specific context key

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

                         
                        Native iOS
                    
​x
 
[[NSNotificationCenter defaultCenter] addObserverForName:  @"This app cannot be installed from unofficial app stores. For your protection, the app will close. Please contact support" object:nil queue:nil usingBlock:^(NSNotification *org_note) {
    __block NSNotification *note = org_note;
    dispatch_async(dispatch_get_main_queue(), ^(void) {
        var threatEventsScore = intent.getStringExtra("threatEventsScore") 
        NSString *message = [[note userInfo] objectForKey:@"message"]; // Message shown to the user
        NSString *reasonData = [[note userInfo] objectForKey:@"reasonData"]; // Threat detection cause
        NSString *reasonCode = [[note userInfo] objectForKey:@"reasonCode"]; // Event reason code
        NSString *currentThreatEventScore = [[note userInfo] objectForKey:@"currentThreatEventScore"]; // Current threat event score
        NSString *threatEventsScore = [[note userInfo] objectForKey:@"threatEventsScore"]; // Total threat events score
        NSString *variable = [[note userInfo] objectForKey:@"<Context Key>"]; // Any other event specific context key
​
        // Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
    });
}];

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

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

                export function registerToAllEvents() {
                    registerToDevEvent(
                        "This app cannot be installed from unofficial app stores. For your protection, the app will close. Please contact support",
                        (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(
        "This app cannot be installed from unofficial app stores. For your protection, the app will close. Please contact support",
        (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("This app cannot be installed from unofficial app stores. For your protection, the app will close. Please contact support"));
                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("This app cannot be installed from unofficial app stores. For your protection, the app will close. Please contact support"));
​
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)"This app cannot be installed from unofficial app stores. For your protection, the app will close. Please contact support", // 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("This app cannot be installed from unofficial app stores. For your protection, the app will close. Please contact support", 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("This app cannot be installed from unofficial app stores. For your protection, the app will close. Please contact support", 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 App Store Signature Validation:

To use Appdome’s mobile app security build system to Validate App Store Signature Validation , you’ll need:

Appdome account (create a free Appdome account here)
A license for App Store Signature Validation
Mobile App (.ipa For iOS)
Signing Credentials (see Signing Secure Android apps and Signing Secure iOS apps)

Using Appdome, there are no development or coding prerequisites to build secured iOS Apps by using App Store Signature Validation. 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 App Store Signature Validation

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 Prevent Fake iOS Apps Using Signature Validation

Why Should Developers Prevent the Running of non-authorized apps?

How does Appdome Prevent the Running of non-Authorized Apps?

Validate App Store Signature Validation on iOS apps using Appdome

Upload the Mobile App to Appdome.

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

Build the feature: App Store Signature Validation.

Building App Store Signature Validation by using Appdome’s DEV-API:

Building the App Store Signature Validation feature via Appdome Console

Certify the App Store Signature Validation feature in iOS Apps.

Using Threat-Events™ for App Store Signature Validation Intelligence and Control in iOS Apps

Prerequisites to Using App Store Signature Validation:

Related Articles:

Thank you!