How to Use Runtime Bundle Validation to Prevent Dynamic Modding in Android & iOS apps

Learn to Prevent Dynamic Modding in Mobile apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

What is Dynamic Modding?

Appdome Runtime Bundle Validation ensures the integrity of iOS and Android apps by running checksums on every file included in the app bundle. Appdome saves cryptographic hashes of the files in the application and compares them to the actual files that are used during runtime. In addition, because some files are changed by Google and Apple after publishing the app, Appdome saves specific content portions for these files and compares the relevant content, as opposed to performing a blind hash validation. This ensures highly accurate detection and minimizes false positives.    Runtime Bundle Validation protects against advanced mobile app tampering techniques and prevents dynamic modding and other forms of tampering.

Keep reading to learn how to use Appdome to protect any Android and iOS app using Runtime Bundle Validation.

Why Prevent Dynamic Modding in Mobile Apps?

Any Android or iOS app can be modified and re-signed by malicious actors, either by adding to or altering the application executable and/or libraries to make an app behavior or function differently. Or they can change assets and resources in order to change the look and feel of an app. This type of malicious activity is often done for the purpose of tricking mobile app users into installing fake malicious apps which they believe are legitimate/useful apps, or to unknowingly download Trojans, botnets, or other malware that can be controlled or updated remotely.

If running on a jailbroken or rooted device, the fraudster could also bypass signature checks or other security controls, which makes the app and/or users highly susceptible to abuse, trickery and other forms of mobile fraud.  To prevent unauthorized file-level modifications, mobile developers can use Appdome’s  Runtime Bundle Validation to validate the integrity of each code section of the app on a file-by-file basis, to prevent against highly targeted, sophisticated app alternations that attempt to conceal the activity.

Preventing Dynamic Modding on Mobile apps by Using Appdome

On Appdome, follow these 3 simple steps to create self-defending Mobile Apps that Prevent Dynamic Modding 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. Mobile App Formats: .ipa For iOS device or .apk or .aab

2. Build the feature: Runtime Bundle Validation.

   1. Building Runtime Bundle Validation by using Appdome’s DEV-API:

      1. Create and name the Fusion Set (security template) that will contain the Runtime Bundle Validation feature as shown below:
      

      Figure 1: Fusion Set that will contain the Runtime Bundle Validation 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 Runtime Bundle Validation feature via Appdome Console, to add the Runtime Bundle Validation 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 Runtime Bundle Validation feature via Appdome Console

      To build the Runtime Bundle Validation protection by using Appdome Console, follow the instructions below.

      1. Where: Inside the Appdome Console, go to Build > Anti Fraud Tab > Mobile Cheat Prevention section
      2. How: Toggle (turn ON) Runtime Bundle Validation, as shown below.
         If needed, Customize the Threat Notification to be displayed to the mobile end-user in a standard OS dialog notification when Appdome Prevents Dynamic Modding.

         Figure 3: Prevent Dynamic Modding option
         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.

      3. When you select the Runtime Bundle Validation you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Runtime Bundle Validation

         

         Figure 4: Fusion Set that displays the newly added Runtime Bundle Validation protection

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

   Congratulations!  The Runtime Bundle Validation protection is now added to the mobile app

3. Certify the Runtime Bundle Validation feature in Mobile Apps.

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