How to Protect Obj-C SelRef iOS Apps with Appdome OneShield

Last updated May 15, 2024 by Appdome

Learn to Protect Obj-C SelRef in iOS apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

What is Objective-C SelRef Protection?

Obj-C SelRef Protection is a security feature integrated into Appdome’s OneShield suite designed to monitor and protect the selector references in Objective-C applications. Objective-C uses selectors to dynamically reference method names and map them to corresponding implementations. These selectors are stored in a global selector table, which the Objective-C runtime relies on to resolve method calls. The Mach-O file format, used in the Apple ecosystem, houses these selectors in a plaintext format, making them susceptible to manipulation. Obj-C SelRef Protection keeps an eye on this structure, ensuring that its integrity remains intact.

How Does Obj-C SelRef Protection Secure iOS Apps?

Obj-C SelRef Protection is essential for mobile app developers who wish to safeguard their applications against manipulation and tampering. By monitoring the SelRef section and its structure, this feature ensures that no unauthorized changes are made to the selector table, a crucial component for method resolution. If a hacker attempts to change the name of a selector, the protection identifies the modification and promptly shuts down the mobile application. For example, a hacker might attempt to hook a function by modifying the selector’s name, resulting in the caller invoking an unintended implementation. This could lead to a situation where a function meant to display a “Hello World” message ends up executing a function that performs malicious actions instead. By identifying such tampering attempts, Obj-C SelRef Protection shuts down the application, thus maintaining the integrity of the app’s logic, visuals, and mechanics. This helps prevent potential vulnerabilities such as code injection, making it a vital feature for secure mobile app development.

Prerequisites for Using Obj-C SelRef Protection:

To use Appdome’s mobile app security build system to Protect Obj-C SelRef , you’ll need:

Protect Obj-C SelRef on iOS apps using Appdome

On Appdome, follow these 3 simple steps to create self-defending iOS Apps that Protect Obj-C SelRef 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. iOS Formats: .ipa
    4. Obj-C SelRef Protection Compatible With: Obj-C, Java, Swift, Flutter, React Native, Unity, Xamarin, Cordova and more
  2. Build the feature: Obj-C SelRef Protection.

    1. Building Obj-C SelRef Protection by using Appdome’s DEV-API:

      1. Create and name the Fusion Set (security template) that will contain the Obj-C SelRef Protection feature as shown below:
      2. fusion set that contains Obj-C SelRef Protection

        Figure 1: Fusion Set that will contain the Obj-C SelRef Protection 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 Obj-C SelRef Protection feature via Appdome Console, to add the Obj-C SelRef Protection 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 Obj-C SelRef Protection feature via Appdome Console

      To build the Obj-C SelRef Protection protection by using Appdome Console, follow the instructions below.

      1. Where: Inside the Appdome Console, go to Build > Security Tab > ONEShield™ section.
      2. When you select the Obj-C SelRef Protection you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Obj-C SelRef Protection

        Fusion Set applied Obj-C SelRef Protection

        Figure 4: Fusion Set that displays the newly added Obj-C SelRef Protection protection

      3. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
    Congratulations!  The Obj-C SelRef Protection protection is now added to the mobile app

Using Threat-Events™ for Obj-C SelRef Intelligence and Control in iOS Apps

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

The specifications and options for Threat-Events™ for Obj-C SelRef are:

Threat-Event™ Elements Protect Obj-C SelRef Method Detail
Appdome Feature Name Obj-C SelRef Protection
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 Protecting Obj-C SelRef 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
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
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), iOS developers can get detailed attack intelligence and granular defense control in iOS applications and create amazing user experiences for all mobile end users when Obj-C SelRef is detected.

The following is a code sample for native iOS apps, which uses all values in the specification above for Obj-C SelRef Protection:

Using Appdome, there are no development or coding prerequisites to build secured iOS Apps by using Obj-C SelRef Protection. 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 Obj-C SelRef Protection

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:

How to Prevent Code Tampering in Android & iOS Apps

How to Automatically Validate Android and iOS App Logic & File Structure in CI/CD

How to Obfuscate Security Features on Appdome


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