How to Detect Malware Privilege Escalation to AccessibilityService

Last updated August 11, 2022 by Appdome

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:

  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
  2. Build the Protection: Detect Accessibility Abuse.

    1. Building Detect Accessibility Abuse by using Appdome’s DEV-API:

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

        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).

      3. 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.

      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, Cirlce 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 Detect Accessibility Abuse feature via Appdome Console

      To build the Detect Accessibility Abuse protection by using Appdome Console, follow the instructions below.

      1. Where: Inside the Appdome Console, go to Build > Anti Fraud Tab > Mobile Fraud Prevention section
      2. How: Toggle (turn ON) Detect Accessibility Abuse, as shown below. Detect Accessibility Abuse option

        Figure 3: Prevent AccessibilityService abuse option

      3. 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

        Fusion Set applied Detect Accessibility Abuse

        Figure 4: Fusion Set that displays the newly added Detect Accessibility Abuse protection

      4. Select the Threat-Event™ in-app mobile Threat Defense and Intelligence policy for Detect Accessibility Abuse:
        1. 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.

        2. 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.

        3. 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.

      5. Optional Configuration with Detect Accessibility Abuse:
        1. Allow Accessibility with Specified Apps

          Allows adding one or more apps that have been approved to enable and use Android AccessibilityService.

      6. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
    Congratulations!  The Detect Accessibility Abuse protection is now added to the mobile app
  3. 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: Detect Accessibility Abuse shown in Certificate secure

    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
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 DETECTON 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:

Prerequisites to Using Detect Accessibility Abuse:

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

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:

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

Protections Similar to Detect Accessibility Abuse

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!

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