How to Detect Malware Privilege Escalation to AccessibilityService

Learn to Detect 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 Detect 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.

Detecting AccessibilityService abuse on Android apps by Using Appdome

On Appdome, follow these 3 simple steps to create self-defending Android Apps that Detect 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 feature: Accessibility Service Abuse.

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

      1. Create and name the Fusion Set (security template) that will contain the Accessibility Service Abuse feature as shown below:
      

      Figure 1: Fusion Set that will contain the Accessibility Service Abuse feature
      Note: Naming the Fusion Set to correspond to the protection(s) selected is for illustration purposes only (not required).

      2. Follow the steps in Sections 2.2.1-2.2.2 of this article, Building the Accessibility Service Abuse feature via Appdome Console, to add the Accessibility Service Abuse 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:

         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 Accessibility Service Abuse feature via Appdome Console

      To build the Accessibility Service Abuse 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) Accessibility Service Abuse, as shown below.

         Figure 3: Detect AccessibilityService abuse option

      3. When you select the Accessibility Service 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 Accessibility Service Abuse

         

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

      4. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).

   Congratulations!  The Accessibility Service Abuse protection is now added to the mobile app

3. Certify the Accessibility Service Abuse feature in Android Apps.

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