RE-Basics

This is my personal repository used for taking notes about iOS reverse engineering tools usage. As I work on solutions aiming to detect malicious activity I need to have a basic understanding of what reverse engineering looks like from the inside. And my goal here is to gather notes and structure my knowledge.

This setup was used for iPhone 7 iOS 13.1.3, macOS Big Sur in July 2021

Setting up an environment

Jailbreak the device

I've used checkra1n 0.12.4 beta: https://checkra.in/

Alternatives: https://unc0ver.dev/ https://taurine.app/ https://canijailbreak.com/

Set up SSH

Follow instructions in Cydia. Install OpenSSH from Cydia (any author will do). Connect to your device by its IP address like

$ ssh root@192.168.1.100

The initial password is alpine Change the password to a more secure one

$ passwd

Install Frida on the device

Open Cydia and add Frida repository to sources https://build.frida.re. Find Frida package in it and install it. Alternatevly, you can do this through SSH.

Set up your Mac

You need to have npm and pip3 installed.

Install applesign

$ npm install -g applesign

Install insert_dylib:

$ cd ~/Documents
$ git clone https://github.com/Tyilo/insert_dylib
$ cd insert_dylib
$ xcodebuild
$ cp build/Release/insert_dylib /usr/local/bin/insert_dylib

Install Frida tools

$ pip3 install frida-tools

Install objection

$ pip3 install objection

Install ios-deploy

$ npm install -g ios-deploy

Getting an .ipa file

There are 3 approaches I suggest:

1. Get a encrypted .ipa easily through SSH. It is useful if you need an unprotected data like .plist file.
2. Do it manually using Frida. I still need to learn how to do this 😅
3. Use ready-to-go scripts and tool (that is what I do). As of right now I recommend bagbak https://github.com/ChiChou/bagbak

$ bagbak MyApplicationName -z

Troubleshooting bagbak

Required node version: 14.x (my: 14.17.0)

Required bagbak version: 2.0

Installed Frida version: 14.2.18

If there is a ploblem with missing Frida Gadget: Check current Frida version. Go to its Github Releases: https://github.com/frida/frida/releases and download Frida Gadget for iOS for the Frida version you have. Then, copy it to the required place.

frida --version
mkdir -p ~/.cache/frida
cp frida-gadget.dylib ~/.cache/frida/gadget-ios.dylib

Patching and signing

You need a valid provisioning profile. You can create a test app in Xcode and run it on the device. It will create a profile for you and objection should be able to find it. To find you signing ID use:

$ security find-identity -p codesigning -v

Get an .ipa from the device and use objection to insert Frida's .dylib. Use an ID from the result above:

$ objection patchipa -c 42ABCDEF99 -s MyApplicationName.ipa

Alternatevly you can specify provisioning file manually. To get it from DerivedData: /MyApplicationName-lwjh.../Build/Products/Debug-iphoneos/MyApplicationName.app/embedded.mobileprovision

$ objection patchipa --source MyApplicationName.ipa --codesign-signature 42ABCDEF99 --provision-file embedded.mobileprovision

Unzip the patched .ipa file to see a Payload folder. Install a patched .app on the device:

$ ios-deploy --bundle ./Payload/MyApplicationName.app -W -d

Troubleshooting failed application verificarion

applesign 3.7.0 is not compatible with objection 1.9.6. You will get an error when installing with ios-deploy:

...
[ 57%] ExtractingPackage
[ 60%] InspectingPackage
[ 60%] TakingInstallLock
[ 65%] PreflightingApplication
[ 65%] InstallingEmbeddedProfile
[ 70%] VerifyingApplication
2020-12-08 14:45:30.398 ios-deploy[30091:873131] [ !! ] Error 0xe800003a: The application could not be verified. AMDeviceSecureInstallApplication(0, device, url, options, install_callback, 0)

Solution:

• Downgrade applesign or
• Sign it one more time adding -c

$ applesign -m embedded.mobileprovision -i 42ABCDEF99 -c -o signed.ipa MyApplicationName-frida-codesigned.ipa

The problen went away with the next setup:

ios-deploy: 1.11.4

applesign: 3.8.0

objection: 1.11.0

Using objection

Run the app on the device.

Use frida to see running processes

$ frida-ps -Uia

Find your app and launch objection

$ objection --gadget "com.hello.myapp" explore

Enjoy!

Also, use it with fancy UI with passionfruit https://github.com/chaitin/passionfruit