How to Enforce Minimum TLS Version, Prevent TLS/SSL Attacks in Android & iOS Apps

Last updated June 2, 2024 by Appdome

Learn to Block connections using TLS version lower than 1.2 in Mobile apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

Which Connection are Using TLS Version Lower than 1.2?

The TLS/SSL protocol supports a wide range of cryptographic algorithms for establishing a secure communication channel and communicating over it.

Every secure connection begins with a “handshake” during which several parameters of the communication are decided. One of which is the version of the protocol:

  • SSL 3.0 (released in 1996)
  • TLS 1.0
  • TLS 1.1
  • TLS 1.2 (released in 2008)
  • TLS 1.3 (released in August 2018, not yet fully adopted)

Old versions of the protocol carry some vulnerabilities. Attacks like POODLE and BEAST rely on exploiting weaknesses of older implementations of TLS.In addition, it is not uncommon for attackers to intentionally impersonate servers or weaken their parameters in order to downgrade the security/encryption of a TLS session so that they can attack it more easily.

Why Block connections using TLS version lower than 1.2 in Mobile Apps?

A very effective countermeasure against this class of attacks is to only use a current version or the latest version of TLS. Implementing and especially maintaining such measures is a difficult task. Sometimes the source code is not available, and more often the services are on uncontrolled endpoints.

Appdome Enforce TLS Version ensures that network connections conform to TLS 1.2 version or higher.

Prerequisites for Using Enforce TLS Version:

To use Appdome’s mobile app security build system to Block connections using TLS version lower than 1.2 , you’ll need:

Block connections using TLS version lower than 1.2 on Mobile apps using Appdome

On Appdome, follow these 3 simple steps to create self-defending Mobile Apps that Block connections using TLS version lower than 1.2 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. Enforce TLS Version Compatible With: Obj-C, Java, JS, C#, C++, Swift, Kotlin, Flutter, React Native, Unity, Xamarin, and more
  2. Build the feature: Enforce TLS Version.

    1. Building Enforce TLS Version by using Appdome’s DEV-API:

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

        Figure 1: Fusion Set that will contain the Enforce TLS Version 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 Enforce TLS Version feature via Appdome Console, to add the Enforce TLS Version 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, Circle 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 Enforce TLS Version feature via Appdome Console

      To build the Enforce TLS Version protection by using Appdome Console, follow the instructions below.

      1. Where: Inside the Appdome Console, go to Build > Security Tab > Secure Communication section.
      2. When you select the Enforce TLS Version you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Enforce TLS Version

        Fusion Set applied Enforce TLS Version

        Figure 4: Fusion Set that displays the newly added Enforce TLS Version protection

      3. Select the Threat-Event™ in-app mobile Threat Defense and Intelligence policy for Enforce TLS Version:
        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 Block connections using TLS version lower than 1.2.

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

          When this setting is used, Appdome detects that the TLS version is lower than 1.2 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 Enforce TLS Version Intelligence and Control in Mobile Apps.

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

          When this setting is used, Appdome detects and defends against connections using TLS version lower than 1.2 (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 Enforce TLS Version Intelligence and Control in Mobile Apps.

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

Using Threat-Events™ for connections using TLS version lower than 1.2 Intelligence and Control in Mobile Apps

Appdome Threat-Events™ provides consumable in-app mobile app attack intelligence and defense control when connections using TLS version lower than 1.2 is detected. To consume and use Threat-Events™ for connections using TLS version lower than 1.2 in Mobile Apps, use AddObserverForName in Notification Center, and the code samples for Threat-Events™ for connections using TLS version lower than 1.2 shown below.

The specifications and options for Threat-Events™ for connections using TLS version lower than 1.2 are:

Threat-Event™ Elements Block connections using TLS version lower than 1.2 Method Detail
Appdome Feature Name Enforce TLS Version
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 Blocking connections using TLS version lower than 1.2 Threat-Event™
Threat-Event NAME SslIncompatibleVersion
Threat-Event DATA reasonData
Threat-Event CODE reasonCode
Threat-Event REF 6502
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
host The host that failed SSL version validation
IncompatibleSslVersion Current SSL version
DeveventDetailedErrorMessage Error message
extendedMessageText Extended message

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 connections using TLS version lower than 1.2 is detected.

The following is a code sample for native Mobile apps, which uses all values in the specification above for Enforce TLS Version:


Using Appdome, there are no development or coding prerequisites to build secured Mobile Apps by using Enforce TLS Version. 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 Enforce TLS Version

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:

You can read about all the properties and features of various TLS versions in Wikipedia.

If you are interested in limiting other aspects of TLS, you should check out how you can Enforce Communications’ Cipher Suites.

This feature is just one of many offered in the course of Trusted Session Inspection.

To zoom out on this topic, visit Appdome for Mobile App Security on our website.

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

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