How to Prevent Vishing Fraud in Android & iOS Apps

Last updated March 13, 2024 by Appdome

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

What is Vishing Fraud?

Preventing Vishing fraud focuses on identifying instances where a mobile app is used during an active phone call. While this concurrent use isn’t inherently fraudulent, it becomes significant in certain contexts, particularly during sensitive transactions. For example, if an individual engages in a mobile app activity while on an active call related to a sensitive transaction (such as discussing financial details, making a high-value purchase, or conducting a verification process), this parallel action could raise a security alert. The feature doesn’t automatically assume fraud per se but rather flags such scenarios for additional scrutiny. This is due to the potential risks associated with the simultaneous handling of sensitive activities, which might be indicative of suspicious behavior.

Why Detecting Vishing Fraud is Vital?

While using a mobile app during an active call is not inherently fraudulent, the context and the specific actions being performed simultaneously can raise alerts within fraud detection systems. This is done to protect users and organizations from potential fraudulent activities, identity theft, or security breaches. These alerts trigger further verification steps or investigation to ensure the legitimacy and security of transactions or interactions taking place. This becomes particularly critical when we examine real-world scenarios where such detection capabilities are essential such as:

Fraud Patterns: In some cases, fraudsters may use multiple channels simultaneously to perpetrate fraudulent activities. For example, they might attempt to social engineer a call center representative while using an app to manipulate or access accounts simultaneously. Such simultaneous activities could raise red flags in fraud detection systems.

Anomalous Behavior: Unusual behavior patterns detected by fraud detection systems, such as a sudden change in user behavior (like accessing a banking app during an ongoing call with a customer service representative for an account-related issue), might trigger alerts for potential fraudulent activities.

Risk Mitigation: For security reasons, certain organizations or financial institutions might set policies or algorithms that flag any deviation from standard user behavior, especially during sensitive transactions, to mitigate potential risks associated with fraud or data breaches.

How does Appdome Protect Mobile Apps Against Vishing Fraud?

To protect Android & iOS apps against Vishing Fraud, Appdome implements the following detection methods:

1. App In Use: Detects vishing attempts when the app is actively being used, during incoming calls.

2. App In Foreground: Scans for vishing attempts when the app is open and visible on the screen.

3. User Uses App and Call Together: Detects simultaneous app use and phone calls.

4. User Opens App after Call Starts: Detects if the app is launched after a phone call has begun, for vishing risk assessment.

All these protection measures are designed to provide an extra layer of security, alerting app developers to suspicious calls that could be attempting to steal app users personal details or financial information.”

Prerequisites for Using Vishing Fraud Prevention:

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

Prevent Vishing Fraud on Mobile apps using Appdome

On Appdome, follow these 3 simple steps to create self-defending Mobile Apps that Prevent Vishing Fraud 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, or .apk or .aab for Android
    4. Vishing Fraud Prevention Compatible With: Obj-C, C+, Java, JS, C#, C++, Swift, Kotlin, Flutter, React Native, Unity, Xamarin, and more
  2. Build the feature: Vishing Fraud Prevention.

    1. Building Vishing Fraud Prevention by using Appdome’s DEV-API:

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

        Figure 1: Fusion Set that will contain the Vishing Fraud Prevention 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 Vishing Fraud Prevention feature via Appdome Console, to add the Vishing Fraud Prevention 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 Vishing Fraud Prevention feature via Appdome Console

      To build the Vishing Fraud Prevention protection by using Appdome Console, follow the instructions below.

      1. Where: Inside the Appdome Console, go to Build > Anti Fraud Tab > Social Engineering Prevention section.
      2. When you select the Vishing Fraud Prevention you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Vishing Fraud Prevention

        Fusion Set applied Vishing Fraud Prevention

        Figure 4: Fusion Set that displays the newly added Vishing Fraud Prevention protection

      3. Select the Threat-Event™ in-app mobile Threat Defense and Intelligence policy for Vishing Fraud Prevention:
        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 Vishing Fraud.

        2. Threat-Events™ ON > In-App Detection

          When this setting is used, Appdome detects if a call is taking place while an application is open on the mobile device 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 Vishing Fraud Prevention Intelligence and Control in Mobile Apps.

        3. Threat-Events™ ON > In-App Defense

          When this setting is used, Appdome detects and defends against Vishing Fraud (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 Vishing Fraud Prevention Intelligence and Control in Mobile Apps.

      4. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
    Congratulations!  The Vishing Fraud Prevention protection is now added to the mobile app

Using Threat-Events™ for Vishing Fraud Intelligence and Control in Mobile Apps

Appdome Threat-Events™ provides consumable in-app mobile app attack intelligence and defense control when Vishing Fraud is detected. To consume and use Threat-Events™ for Vishing Fraud in Mobile Apps, use AddObserverForName in Notification Center, and the code samples for Threat-Events™ for Vishing Fraud shown below.

The specifications and options for Threat-Events™ for Vishing Fraud are:

Threat-Event™ Elements Prevent Vishing Fraud Method Detail
Appdome Feature Name Vishing Fraud Prevention
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 Vishing Fraud Threat-Event™
Threat-Event NAME ActivePhoneCallDetected
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
message Message displayed for the user on event
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
deviceID Current device ID
reasonCode Reason code of the occured event
buildDate Appdome fusion date of the current application
devicePlatform OS name of the current device
carrierName Carrier name of the current device
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

With Threat-Events™ enabled (turned ON), Mobile developers can get detailed attack intelligence and granular defense control in Mobile applications and create amazing user experiences for all mobile end users when Vishing Fraud is detected.

The following is a code sample for native Mobile apps, which uses all values in the specification above for Vishing Fraud Prevention:

Using Appdome, there are no development or coding prerequisites to build secured Mobile Apps by using Vishing Fraud Prevention. 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 Vishing Fraud Prevention

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:

Related Articles:

If you have any questions, please send them our way at or via the chat window on the Appdome platform.

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