iOS

  • iOS devices are naturally limited compared to Android

  • Apple keeps a "walled garden" of apps you can install and utilize

    • Can be bypassed using Jailbreaking

  • xCode is the supported development for iOS

  • Many iOS devices have a hardware security components, and in certain cases even replacing physical part can cause the phone to error.

iOS Security Architecture

  • Hardware and Software layer

  • Apps run in Sandbox environment.

    • Similar to Android, it is based on Unix.

    • All apps are signed by Apple

    • We need developer profile and pay yearly fee to put apps on App Store.

    • (Free Developer account allows Sideloading)

  • Two patitions in the file system. Hardware and Software.

  • Each iOS Device has two keys created and put into the device during manufacturing.

Static Analysis for iOS

  • Apps are developed using Swift.

  • Apps are in a .iPA format

  • .ipa is signed bundle of folders and assets

    • /Payload/Application.app - the application itself.

    • /Payload/iTunesMetadata.plist - Info about the app developer.

    • /Payload/Application.app/Info.plist - Where important app info is stored (Similar to AndroidManifest.xml). This is a key-value type file.

    • Various .json files, assets or resources unique to the app

Use Xcode for development, and static analysis of iPA file.

Check system.log for any sensitive information.

AnyTrans

Tool to pull iPA files from AppStore.

Connect iPhone to AnyTrans and download App on device. Now, we can download the same iPA using AnyTrans.

Other Emulating Tools

Corellium and Appetize.io

Manual Static Analysis

Rename the iPA file to .zip

Unzip the file. We can now check .app file using the "Show package contents"

We can now see all the files such as Info.plist

Automated Static Analysis using MobSF

Dynamic Analysis

Setup Burp and import Certificate/Profile and install the certificate.

Goto About/Certificate Settings and enable Trust for Burp certificate.

Breaking SSL Pinning for iOS

  • We can use Objection to patch the iPA and disable SSL Pinning.

    • Requires physical device to receive a provisioning profile.

    • May not work in all cases.

  • The last kill resort will be to utilize a jailbroken iOS device and use tools like SSL KillChain to break SSL Pinning.

Patching iPA using Objection

Install objection.

pip3 install frida-tools
pip3 install objection

Patch with code signed signature from Xcode via Developer profile.

Goto any project in Xcode and export the profile to device. Trust the developer profile on device.

# Get code signed signature
security find-identity


objection patchipa --source app.ipa -c 67213423A423EDFADSFG23423423ASDFDF

Jailbreaking

checkra1n

  • Download checkra1n for macOS.

  • Allow untested iOS in checkra1n

  • Follow instructions on checkra1n

  • If we see Cydia installed, it means Jailbreak is successful.

Cydia

We can install apps using Cydia.

SSL Kill Switch for bypassing SSL Pinning

Install via Jailbreak and download on macbook and push on device to break SSL Pinning.

  • Open Cydia and install wget

  • SSH into jailbroken device and download the package in /tmp folder using wget.

  • dpkg -i com.nablac0d3.sslkillswitch_0.14.deb

  • If you get an error, run apt --fix-broken install

  • Open iOS settings app, locate SSL Kill Switch 2.

  • Open it and enable "Disable Certificate Validation".

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