How to Detect Malware Privilege Escalation to AccessibilityService
Learn to Prevent AccessibilityService abuse in Android apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.
What is Android AccessibilityService?
AccessibilityServices are OS settings/features in Android that are designed to help users with disabilities (for example: screen readers, speech to text, touch events). These features run in the background and receive callbacks by the system when accessibility events are fired, making them capable of reacting to a state transition in the UI (for example: focus has changed, button was clicked, or content in the active window was queried).
Why Prevent AccessibilityService abuse in Android Apps?
AccessibilityServices features enabled in an app typically provide the app with permissions that can be abused, especially if the app is a clone, trojan, or malware app. Such malicious apps often request elevated permissions or trick users into enabling AccessibilityServices which the app will then abuse (at the expense of the user or your app). The malware might abuse the user or target application by using the Accessibility feature or associated permissions for malicious and unintended reasons. The potential malicious uses of AccessibilityServices services include performing click actions (for example, committing click fraud, inputting data into forms fraudulently, impersonating the real mobile user, or cheating in mobile games). Other potential abusive actions are reading and writing SMS messages and emails, intercepting and reading 2FA codes, stealing cryptocurrency keys, and remotely controlling mobile devices or apps.
For these reasons, it is advisable to be aware that the AccessibilityServices services are enabled for a malicious app and protect the target application (your app) from being abused or compromised.
Preventing AccessibilityService abuse on Android apps by Using Appdome
On Appdome, follow these 3 simple steps to create self-defending Android Apps that Prevent AccessibilityService abuse without an SDK or gateway:
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Upload the Mobile App to Appdome.
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Upload an app to Appdome’s Mobile App Security Build System
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Upload Method: Appdome Console or DEV-API
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Android Formats: .apk or .aab
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Build the feature: Detect Accessibility Abuse.
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Building Detect Accessibility Abuse by using Appdome’s DEV-API:
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Create and name the Fusion Set (security template) that will contain the Detect Accessibility Abuse feature as shown below:
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Follow the steps in Sections 2.2.1-2.2.2 of this article, Building the Detect Accessibility Abuse feature via Appdome Console, to add the Detect Accessibility Abuse feature to this Fusion Set.
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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). -
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:
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Build an API for the app – for instructions, see the tasks under Appdome API Reference Guide
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Look for sample APIs in Appdome’s GitHub Repository
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Figure 1: Fusion Set that will contain the Detect Accessibility Abuse feature
Note: Naming the Fusion Set to correspond to the protection(s) selected is for illustration purposes only (not required). -
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Building the Detect Accessibility Abuse feature via Appdome Console
To build the Detect Accessibility Abuse protection by using Appdome Console, follow the instructions below.
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Where: Inside the Appdome Console, go to Build > Anti Fraud Tab > Mobile Fraud Prevention section
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How: Toggle (turn ON) Detect Accessibility Abuse, as shown below.
Figure 3: Prevent AccessibilityService abuse option
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When you select the Detect Accessibility Abuse you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Detect Accessibility Abuse
Figure 4: Fusion Set that displays the newly added Detect Accessibility Abuse protection
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Select the Threat-Event™ in-app mobile Threat Defense and Intelligence policy for Detect Accessibility Abuse:
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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 AccessibilityService abuse.
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Threat-Events™ ON > In-App Detection
When this setting is used, Appdome detects that the AccessibilityServices services are enabled 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 Detect Accessibility Abuse Intelligence and Control in Mobile Apps.
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Threat-Events™ ON > In-App Defense
When this setting is used, Appdome detects and defends against AccessibilityService abuse (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 Detect Accessibility Abuse Intelligence and Control in Mobile Apps.
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- Optional Configuration with Detect Accessibility Abuse:
- Allow Accessibility with Specified Apps
Allows adding one or more apps that have been approved to enable and use Android AccessibilityService.
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Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
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Congratulations! The Detect Accessibility Abuse protection is now added to the mobile app -
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Certify the Detect Accessibility Abuse feature in Android Apps.
After building Detect Accessibility Abuse, Appdome generates a Certified Secure™ certificate to guarantee that the Detect Accessibility Abuse protection has been added and is protecting the app. To verify that the Detect Accessibility Abuse 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 Detect Accessibility Abuse has been added to each Android app. Certified Secure provides instant and in-line DevSecOps compliance certification that Detect Accessibility Abuse and other mobile app security features are in each build of the mobile app
Using Threat-Events™ for AccessibilityService abuse Intelligence and Control in Android Apps
Appdome Threat-Events™ provides consumable in-app mobile app attack intelligence and defense control when AccessibilityService abuse is detected. To consume and use Threat-Events™ for AccessibilityService abuse in Android Apps, use registerReceiver in the Application OnCreate, and the code samples for Threat-Events™ for AccessibilityService abuse shown below.
The specifications and options for Threat-Events™ for AccessibilityService abuse are:
Threat-Event™ Elements | Prevent AccessibilityService abuse Method Detail |
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Appdome Feature Name | Detect Accessibility Abuse |
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 AccessibilityService abuse Threat-Event™ | |
Threat-Event NAME | AccessibilityServiceDetected |
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 AccessibilityService abuse is detected.
The following is a code sample for native Android apps, which uses all values in the specification above for Detect Accessibility Abuse:
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("AccessibilityServiceDetected");
registerReceiver(new BroadcastReceiver() {
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("AccessibilityServiceDetected")
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(
"AccessibilityServiceDetected",
(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("AccessibilityServiceDetected"));
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("AccessibilityServiceDetected", 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 Detect Accessibility Abuse:
To use Appdome’s mobile app security build system to Prevent AccessibilityService abuse , you’ll need:
- Appdome account (create a free Appdome account here)
- A license for Detect Accessibility Abuse
- 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 Apps by using Detect Accessibility Abuse. 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 Detect Accessibility Abuse
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 Detect Accessibility Abuse
Here are a few related resources:
- How to Prevent abuse of Android AccessibilityService for compromising Android apps
- How to Prevent non-approved Android, iOS app store publishing
- Check out the Appdome Mobile Fraud Preventionsolution page or request a demo at any time.
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.