How to Obfuscate Dynamically Loaded Symbols in iOS Apps

Last updated November 30, 2023 by Appdome

Learn to Obfuscate Dynamically Loaded Symbols in iOS apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

What are Dynamically Loaded Symbols?

Dynamically Loaded Symbols, commonly known as Lazy symbols, are symbols found in iOS binaries (Mach-O format). These symbols are imported from other binaries or dynamically linked libraries, be they from the system or third-party sources, yet they aren’t implemented directly within the binary. Every binary might contain lazy symbols from various libraries. What sets lazy symbols apart is their addressing; Their final address is determined only when the app first tries to use them upon loading. In contrast, all other imported symbols have their addresses resolved during the app’s initial launch, rather than at first use. The responsibility for resolving these imported symbols and identifying their addresses falls to the dyld, the dynamic linker component of iOS.

 

Why It's Necessary to Obfuscate Dynamically Loaded Symbols?

Obfuscating Dynamically Loaded Symbols is vital, especially in the context of defending against static analysis by reversers. Through static analysis, reversers can meticulously extract detailed information about the symbols an app imports. A particular area of concern is the unveiling of cryptographic functions, such as MD5 or SHA256, that the app might be leveraging from system libraries or third-party sources. By discerning which cryptographic methods are in play, reversers not only gain hints about decrypting secured data but also establish a precise anchor pinpointing where and when these functions come into action. Armed with this insight, they can potentially manipulate the app in real-time, disabling or even altering the intended purpose of these imported functions. Given these significant threats, obfuscation stands as not just a protective measure but an imperative shield, ensuring that the app remains inscrutable, safeguarding its intellectual property, data, and overall functionality from potentially disastrous tampering.

Prerequisites for Using Obfuscate Dynamically Loaded Symbols:

To use Appdome’s mobile app security build system to Obfuscate Dynamically Loaded Symbols , you’ll need:

Obfuscate Dynamically Loaded Symbols on iOS apps using Appdome

On Appdome, follow these simple steps to create self-defending iOS Apps that Obfuscate Dynamically Loaded Symbols 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. Obfuscate Dynamically Loaded Symbols Compatible With: Obj-C, Java, Swift, Flutter, React Native, Unity, Xamarin, Cordova and more
  2. Build the feature: Obfuscate Dynamically Loaded Symbols.

    1. Building Obfuscate Dynamically Loaded Symbols by using Appdome’s DEV-API:

      1. Create and name the Fusion Set (security template) that will contain the Obfuscate Dynamically Loaded Symbols feature as shown below:
      2. fusion set that contains Obfuscate Dynamically Loaded Symbols

        Figure 1: Fusion Set that will contain the Obfuscate Dynamically Loaded Symbols 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 Obfuscate Dynamically Loaded Symbols feature via Appdome Console, to add the Obfuscate Dynamically Loaded Symbols 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 Obfuscate Dynamically Loaded Symbols feature via Appdome Console

      To build the Obfuscate Dynamically Loaded Symbols protection by using Appdome Console, follow the instructions below.

      1. Where: Inside the Appdome Console, go to Build > Security Tab > TOTALCode™ Obfuscation section.
      2. When you enable Binding Obfuscation you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Obfuscate Dynamically Loaded Symbols

        Fusion Set applied Obfuscate Dynamically Loaded Symbols

        Figure 4: Fusion Set that displays the newly added Obfuscate Dynamically Loaded Symbols protection

      3. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
    Congratulations!  The Obfuscate Dynamically Loaded Symbols protection is now added to the mobile app

Using Threat-Events™ for Dynamically Loaded Symbols Intelligence and Control in iOS Apps

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

The specifications and options for Threat-Events™ for Dynamically Loaded Symbols are:

Threat-Event™ Elements Obfuscate Dynamically Loaded Symbols Method Detail
Appdome Feature Name Obfuscate Dynamically Loaded Symbols
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 Obfuscating Dynamically Loaded Symbols 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 Dynamically Loaded Symbols is detected.

The following is a code sample for native iOS apps, which uses all values in the specification above for Obfuscate Dynamically Loaded Symbols:


Using Appdome, there are no development or coding prerequisites to build secured iOS Apps by using Obfuscate Dynamically Loaded Symbols. 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 Obfuscate Dynamically Loaded Symbols

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 support.appdome.com or via the chat window on the Appdome platform.

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