How to Block Suspicious Accessibility Services in Android Apps

Last updated March 19, 2023 by Appdome

Learn to Block Suspicious Accessibility Services in Android apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

What are Accessibility Services?

Android Accessibility Services enable Android apps to assist individuals with disabilities in overcoming their challenges when using their smartphones. An example of such services is a screen reading utility. Such a utility (app) makes texts accessible to the blind or visually impaired by providing talking feedback in response to user manipulations and gestures such as swiping, dragging, or using an external keyboard.

When users download these apps, they need to enable Accessibility Permissions in order to take advantage of these benefits.

Why are Accessibility Services Potentially Dangerous?

Accessibility Services run in the background and receive callbacks by the system when accessibility events such as clicking a button or changing a focus are fired. In response to a callback, an accessibility service can request the capability required for querying the content of the active window.

These services also typically run with a higher level of administrative privilege. For this reason, AccessibilityServices are often used for different purposes for which they were not intended and targeted by hackers to exploit. When abused, they are used to perform click actions (either to commit click-fraud or to cheat in mobile games), read and write SMS messages and emails, intercept and read Two-Factor Authentication codes, steal cryptocurrency keys, control mobile devices or apps remotely and more. In addition, when an app is allowed to take full control over a user’s device, this can result in allowing malware to access the device and take control over it. The presence of a malware on a device can eventually lead to the stealing of sensitive information about the user, such as banking information and personal information. This is done by peforming attacks such as clickjacking (hijacking a user’s click on their computer) and banking Trojans that work by stealing banking credentials from users.

The Block Suspicious Accessibility Services feature, which is part of the Anti Remote Desktop Control protection, detects and block accessibility services that are deemed to be suspicious and mal-intentioned.

Blocking Suspicious Accessibility Services on Android apps by Using Appdome

On Appdome, follow these 3 simple steps to create self-defending Android Apps that Block Suspicious Accessibility Services 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
Build the feature: Block Suspicious Accessibility Services.
1. Building Block Suspicious Accessibility Services by using Appdome’s DEV-API:
  1. Create and name the Fusion Set (security template) that will contain the Block Suspicious Accessibility Services feature as shown below:
  2. Follow the steps in Sections 2.2.1-2.2.2 of this article, Building the Block Suspicious Accessibility Services feature via Appdome Console, to add the Block Suspicious Accessibility Services 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 Block Suspicious Accessibility Services feature via Appdome Console
  
  To build the Block Suspicious Accessibility Services protection by using Appdome Console, follow the instructions below.
  1. Where: Inside the Appdome Console, go to Build > Anti Fraud Tab > Mobile Malware Prevention section
  2. How: Toggle (turn ON) Block Suspicious Accessibility Services, as shown below.
    
    Figure 3: Block Suspicious Accessibility Services option
  3. When you select the Block Suspicious Accessibility Services you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Block Suspicious Accessibility Services
    
    Figure 4: Fusion Set that displays the newly added Block Suspicious Accessibility Services protection
  4. Select the Threat-Event™ in-app mobile Threat Defense and Intelligence policy for Block Suspicious Accessibility Services:
    
    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 Block Suspicious Accessibility Services.
    
    Threat-Events™ ON > In-App Detection
    When this setting is used, Appdome detects the existence of suspicious accessibility services 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 Block Suspicious Accessibility Services Intelligence and Control in Mobile Apps.
    
    Threat-Events™ ON > In-App Defense
    When this setting is used, Appdome detects and defends against Suspicious Accessibility Services (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 Block Suspicious Accessibility Services Intelligence and Control in Mobile Apps.
  5. Extra Configuration with Block Suspicious Accessibility Services:
    App Compromise Notification
    The message that will be shown to the user when the event is detected. The app will automatically exit.
    Localized Messages
    Upload file CSV or JSON for the localized compromise notification message. Key/left column locale e.g. en_US, Value/right column the localized message.
  6. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
Congratulations! The Block Suspicious Accessibility Services protection is now added to the mobile app
Certify the Block Suspicious Accessibility Services feature in Android Apps.

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

Using Threat-Events™ for Suspicious Accessibility Services Intelligence and Control in Android Apps

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

The specifications and options for Threat-Events™ for Suspicious Accessibility Services are:

Threat-Event™ Elements	Block Suspicious Accessibility Services Method Detail
Appdome Feature Name	Block Suspicious Accessibility Services
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 Blocking Suspicious Accessibility Services Threat-Event™
Threat-Event NAME	IllegalAccessibilityServiceEvent
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
blocked	was the keyboard blocked (True/False)
buildHost	build server of the ROM (for Android devices)
deviceBoard	the board upon which the mobile device is based (for Android devices)
carrierPlmn	carrier identity number (PLMN code)
defaultMessage	the message that would be shown to the user in enforcement mode
deviceBrand	brand of the mobile device
deviceID	unique mobile installation identifier
deviceManufacturer	manufacturer of the mobile device
deviceModel	mobile device model
extendedMessageText	allows receiving extended metadata about threat events. Available only if the option
fusedAppToken	Appdome Built ID App Token
kernelInfo	Kernel information and details
Keyboard	package ID of the unauthorized keyboard to which the user tried to switch
osVersion	The mobile device OS version
sdkversion	Android SDK Version
timestamp	UNIX timestamp when event happened
OS Platform(s) Method	Android (registerReceiver)

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 Suspicious Accessibility Services are detected.

The following is a code sample for native Android apps, which uses all values in the specification above for Block Suspicious Accessibility Services:

IntentFilter intentFilter = new IntentFilter();
                    intentFilter.addAction("IllegalAccessibilityServiceEvent");
                    registerReceiver(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...)
                            }
                        }, intentFilter);

                        
                        Java
                    
​x
 
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("IllegalAccessibilityServiceEvent");
registerReceiver(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...)
        }
    }, intentFilter);

val intentFilter = IntentFilter()
                intentFilter.addAction("IllegalAccessibilityServiceEvent")
                registerReceiver(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...)
                    }
                }, intentFilter)

                         
                        Kotlin
                    
​x
 
val intentFilter = IntentFilter()
intentFilter.addAction("IllegalAccessibilityServiceEvent")
registerReceiver(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...)
    }
}, 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(
                        "IllegalAccessibilityServiceEvent",
                        (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(
        "IllegalAccessibilityServiceEvent",
        (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("IllegalAccessibilityServiceEvent"));
                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
                
​x
 
RegisterReceiver(new ThreatEventReceiver(), new IntentFilter("IllegalAccessibilityServiceEvent"));
​
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...)
  }
}

window.broadcaster.addEventListener("IllegalAccessibilityServiceEvent", 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("IllegalAccessibilityServiceEvent", 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 Block Suspicious Accessibility Services:

To use Appdome’s mobile app security build system to Block Suspicious Accessibility Services , you’ll need:

Appdome account (create a free Appdome account here)
A license for Block Suspicious Accessibility Services
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 Block Suspicious Accessibility Services. 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 Block Suspicious Accessibility Services

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.

Features Similar to Block Suspicious Accessibility Services

Here are a few related resources:

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 Suspicious Accessibility Services in Android Apps

What are Accessibility Services?

Why are Accessibility Services Potentially Dangerous?

Blocking Suspicious Accessibility Services on Android apps by Using Appdome

Upload the Mobile App to Appdome.

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

Build the feature: Block Suspicious Accessibility Services.

Building Block Suspicious Accessibility Services by using Appdome’s DEV-API:

Building the Block Suspicious Accessibility Services feature via Appdome Console

Certify the Block Suspicious Accessibility Services feature in Android Apps.

Using Threat-Events™ for Suspicious Accessibility Services Intelligence and Control in Android Apps

Prerequisites to Using Block Suspicious Accessibility Services:

Thank you!