How to Protect Android Apps Against Apktool Using AI
Last updated November 20, 2023 by Appdome
This Knowledge Base article describes how to use Appdome’s AI/ML in your CI/CD pipeline to continuously
deliver plugins that Block Apktool in Android apps.
What Is Apktool?
Apktool is an open-source utility for reverse-engineering Android applications, enabling users to decode APK files, extract resources, and access nearly original source code and assets. While beneficial for legitimate uses like bug fixes, attackers exploit Apktool to analyze, alter, and recompile apps. These attacks can embed malicious code, compromise user data, or manipulate in-app transactions. Apktool-based attacks pose significant risks, such as unauthorized data extraction, app tampering, and republishing altered apps with malware. Defending against these attacks is crucial for safeguarding sensitive app content, ensuring compliance with standards like GDPR and PCI-DSS, and protecting the integrity of app functionality and user data.
How Appdome Protects Mobile Apps Against Apktool?
Appdome’s dynamic Anti-APK Tool plugin for Android protects apps from reverse-engineering attempts using tools like Apktool. The plugin secures app code, resources, and assets against decoding, repackaging, and tampering by monitoring for attempts to extract or modify APK files. Even if extracted, the app remains protected, preventing attackers from embedding malicious code or altering functionality. This protection ensures data integrity, blocks unauthorized modifications, and enhances app security without manual developer effort.
Prerequisites for Using Appdome's Anti-Apktool Plugins:
To use Appdome’s mobile app security build system to Block Apktool , you’ll need:
Upload an app via the Appdome Mobile Defense platform GUI or via Appdome’s DEV-API or CI/CD Plugins.
Android Formats: .apk or .aab
Anti-Apktool is compatible with:
Java, JS, C++, C#, Kotlin, Flutter, React Native, Unity, Xamarin, Cordova and other Android apps.
Select the defense: Anti-Apktool.
Create and name the Fusion Set (security template) that will contain the Anti-Apktool feature as shown below:
Figure 1: Fusion Set that will contain the Anti-Apktool feature
Follow the steps in Sections 2.2-2.2.2 of this article to add the Anti-Apktool feature to your Fusion Set via the Appdome Console.
When you enable Anti-Tampering you'll notice that the Fusion Set you created in step 2.1 now bears the icon of the protection category that contains Anti-Apktool.
Figure 2: Fusion Set that displays the newly added Anti-Apktool protection
Note: Annotating the Fusion Set to identify the protection(s) selected is optional only (not mandatory).
Open the Fusion Set Detail Summary by clicking the “...” symbol on the far-right corner of the Fusion Set. Copy
the Fusion Set ID from the Fusion Set Detail Summary (as shown below):
Figure 3: Fusion Set Detail Summary
Follow the instructions below to use the Fusion Set ID inside any standard mobile DevOps or CI/CD toolkit like Bitrise, Jenkins, Travis, Team City, Circle CI or other system:
Add the Anti-Apktool feature to your security template.
Navigate to Build > Security tab > Anti-Reverse Engineering section in the Appdome Console.
Like all other options in ONEShield™, Anti-Apktool is turned on by default, as shown below:
Figure 4: Selecting Anti-Apktool
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.
Toggle On Anti-Tampering > Anti-Apktool.
Figure 4: Selecting Block Apktool
Initiate the build command either by clicking Build My App at the bottom of the Build Workflow (shown in Figure 4)
or via your CI/CD as described in Section 2.1.4.
Congratulations! The Anti-Apktool protection is now added to the mobile app
Certify the Anti-Apktool feature in Android Apps
After building Anti-Apktool, Appdome generates a Certified Secure™ certificate to guarantee that the Anti-Apktool protection has been added and is protecting the app. To verify that the Anti-Apktool 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 Anti-Apktool has been added to each Android app. Certified Secure provides instant and in-line DevSecOps compliance certification that Anti-Apktool and other mobile app security features are in each build of the mobile app.
Using Threat-Events™ for Apktool Intelligence and Control in Android Apps
Appdome Threat-Events™ provides consumable in-app mobile app attack intelligence and defense control when Apktool is detected. To consume and use Threat-Events™ for
Apktool in Android Apps, use registerReceiver in the Application OnCreate, and the code samples for Threat-Events™ for Apktool shown below.
The specifications and options for Threat-Events™ for Apktool are:
Threat-Event™ Elements
Block Apktool Method Detail
Appdome Feature Name
Anti-Apktool
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
x
Visible in ThreatScope™
x
Developer Parameters for Blocking Apktool Threat-Event™
Threat-Event NAME
Threat-Event DATA
reasonData
Threat-Event CODE
reasonCode
Threat-Event REF
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
failSafeEnforce
Timed enforcement against the identified threat
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. Only available for Android devices.
deviceID
Current device ID
reasonCode
Reason code of the occurred event
buildDate
Appdome fusion date of the current application
devicePlatform
OS name of the current device
carrierName
Carrier name of the current device. Only available for Android.
updatedOSVersion
Is the OS version up to date
deviceBrand
Brand of the device
deviceBoard
Board of the device
buildUser
Build user
buildHost
Build host
sdkVersion
Sdk version
timeZone
Time zone
deviceFaceDown
Is the device face down
locationLong
Location longitude conditioned by location permission
locationLat
Location latitude conditioned by location permission
locationState
Location state conditioned by location permission
wifiSsid
Wifi SSID
wifiSsidPermissionStatus
Wifi SSID permission status
threatCode
The last six characters of the threat code specify the OS, allowing the Threat Resolution Center to address the attack on the affected device.
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 Apktool is detected.
The following is a code sample for native Android apps, which uses all values in the specification above for Anti-Apktool:
Important! Replace all placeholder instances of <Context Key> with the specific name of your threat event context key across all language examples. This is crucial to ensure your code functions correctly with the intended event data.
For example, The <Context Key> could be the message, externalID, OS Version, reason code, etc.
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("");
BroadcastReceiver threatEventReceiver = 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
// Current threat event score
String currentThreatEventScore = intent.getStringExtra("currentThreatEventScore");
// Total threat events score
String threatEventsScore = intent.getStringExtra("threatEventsScore");
// Replace '' with your specific event context key
// String variable = intent.getStringExtra("");
// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
}
};
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
registerReceiver(threatEventReceiver, intentFilter, Context.RECEIVER_NOT_EXPORTED);
} else {
registerReceiver(threatEventReceiver, intentFilter);
}
val intentFilter = IntentFilter()
intentFilter.addAction("")
val threatEventReceiver = 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
// Current threat event score
var currentThreatEventScore = intent?.getStringExtra("currentThreatEventScore")
// Total threat events score
var threatEventsScore = intent?.getStringExtra("threatEventsScore")
// Replace '' with your specific event context key
// var variable = intent?.getStringExtra("")
// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
}
}
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
registerReceiver(threatEventReceiver, intentFilter, Context.RECEIVER_NOT_EXPORTED)
} else {
registerReceiver(threatEventReceiver, 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(
"",
(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
// Current threat event score
var currentThreatEventScore = userinfo["currentThreatEventScore"]
// Total threat events score
var threatEventsScore = userinfo["threatEventsScore"]
// Replace '' with your specific event context key
// var variable = userinfo[""]
// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
);
}
// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
26
}
27
}
NSNotificationCenter.DefaultCenter.AddObserver(
(NSString)"", // Threat-Event Identifier
delegate (NSNotification notification)
{
// Message shown to the user
var message = notification.UserInfo.ObjectForKey("message");
// Threat detection cause
var reasonData = notification.UserInfo.ObjectForKey("reasonData");
// Event reason code
var reasonCode = notification.UserInfo.ObjectForKey("reasonCode");
// Current threat event score
var currentThreatEventScore = notification.UserInfo.ObjectForKey("currentThreatEventScore");
// Total threat events score
var threatEventsScore = notification.UserInfo.ObjectForKey("threatEventsScore");
// Replace '' with your specific event context key
// var variable = notification.UserInfo.ObjectForKey("");
// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
}
);
// Replace '<Context Key>' with your specific event context key
21
// var variable = notification.UserInfo.ObjectForKey("<Context Keys>");
22
23
// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
24
}
25
);
window.broadcaster.addEventListener("", 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
// Current threat event score
var currentThreatEventScore = userInfo.currentThreatEventScore
// Total threat events score
var threatEventsScore = userInfo.threatEventsScore
// Replace '' with your specific event context key
// var variable = userInfo.
// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
});
// Replace '<Context Key>' with your specific event context key
13
// var variable = userInfo.<Context Keys>
14
15
// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
16
});
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
class PlatformChannel extends StatefulWidget {
const PlatformChannel({super.key});
@override
State createState() => _PlatformChannelState();
}
class _PlatformChannelState extends State {
// Replace with your EventChannel name
static const String _eventChannelName = "";
static const EventChannel _eventChannel = EventChannel(_eventChannelName);
@override
void initState() {
super.initState();
_eventChannel.receiveBroadcastStream().listen(_onEvent, onError: _onError);
}
void _onEvent(Object? event) {
setState(() {
// Adapt this section based on your specific event data structure
var eventData = event as Map;
// Example: Accessing 'externalID' field from the event
var externalID = eventData['externalID'];
// Customize the rest of the fields based on your event structure
String message = eventData['message']; // Message shown to the user
String reasonData = eventData['reasonData']; // Threat detection cause
String reasonCode = eventData['reasonCode']; // Event reason code
// Current threat event score
String currentThreatEventScore = eventData['currentThreatEventScore'];
// Total threat events score
String threatEventsScore = eventData['threatEventsScore'];
// Replace '' with your specific event context key
// String variable = eventData[''];
});
}
// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
}
// Replace '<Context Key>' with your specific event context key
43
// String variable = eventData['<Context Keys>'];
44
});
45
}
46
47
// Your logic goes here (Send data to Splunk/Dynatrace/Show Popup...)
48
}
Using Appdome, there are no development or coding prerequisites to build secured Android Apps by using Anti-Apktool. 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 Anti-Apktool
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:
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.
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