1. Hacking & Securing
iOS Apps
@GeekCampSG
18th Aug 2012
Subhransu Behera (Subh)
Twitter: @subhransu
Email: subh@subhb.org

2. 1. Hacking iOS Apps

3. About Me
• iOS Application Architect in SAP
• Developing iOS Apps for last 4 Yrs.
• Co-organizer of iOS Dev Scout (iOS Developer Group in SG)
• Worked as a RoR and Linux Developer prior to iOS
• Understand Web, Mobile and Unix Systems
• Have built iOS apps ranging from games to large scale enterprise apps.

4. So, 2 questions
• Are the iDevices secure?
• Are the apps that you developer using iOS SDK secure?
Answer to both the questions are NO

5. I will be Talking on
• How easy it’s to steal data from the apps you are developing
• How to protect these apps
• Not on how to protect your iDevices.

6. System Data
File System Database Bundle
User’s own
iDevice
running your
APP
Backend
Database
Server
other users other users other users
running the running the running the
same app same app same app
You need to protect
File System Database Bundle data both on client
and server side
System Data

7. Apple’s Security Model
Crypto Engine
Data
Protection
Software Class
App Sandbox Hardware and
User Partition Firmware
Device Key
Group Key
OS Partition Apple Root Certificate
Encrypted File System
Kernel

8. Breaking down further
• Reduced Attack Surface
• User & Group Permissions
• Code Signing
• Data Execution Prevention (Data vs Code)
• Sandboxing
• Address Space Layout Randomization

9. In spite of all these, a hacker can
• Steal Data from File System
• Steal Data from Network
• Attack App Server
• Run an Exploit from the iDevice

10. Developers usually store their
application data in
• Bundle
• Document Directory
• Library Directory
• Key Chain
• iCloud or on their own Server

11. Let’s Hack
Some Apps

12. Data from
Bundle Directory

13. Easiest of All
• Some Developers put their database, plist and other data files in bundle
directory
• It’s very easy to extract data available in bundle directory from the
application payload
• Data that you can extract are images, audio, video files, plist, xml files or
any other files that are stored in bundle directory

14. Steps to do it
• Go to iTunes App Directory
• Right click on any app whose data you want to extract
• Select “Show in Finder” option
• You can extract the content of the file if you have tools like “Stuffit
expander”. Otherwise, just rename the app.ipa >> app.zip
• Extract using any unarchive tool
• The binary of the app is within Payload directory.
• Right click on the binary and “Show Package Contents” to
extract the content of bundle directory.

15. Steps to do it
1. Show in 3. Show Package
2. Unarchive
Finder Contents

16. Contents from SGCarParks App
• The app uses sqlite database file stored on Bundle directory to display car park
information in Singapore.
• Below is the content of sqlite file that contains Name of car parks, location
(Latitude, Longitude), ERP Rates of the parking lots on weekdays and
weekends.

17. Following the above steps
• You can extract unencrypted Resource and Media Files
• However, images are encoded by Apple to reduce the size of the binary.
• So by following the above process you can’t extract the images of apps
directly.
• To extract reusable images you need to extraction tools like: Crunch
• http://www.pragmaticcode.com/crunch/

18. Images from Instagram App
• Search the name of the app.
• Select the application and
Click on Export Icon.
• Uncheck “only export
highest definition” to
export all images
• Choose a directory to
export the contents. Images Extracted from
Instagram using Crunch

19. Displaying PVR Images
• PNG images use a significant amount of
memory when a lot of frames are used for
animation.
• So game applications like AngryBird use
PowerVR (commonly known as PVR)
Texture images in stead of PNG images to
reduce memory usage.
• You can use TexturePacker tool to
both create and display PVR Images.
Images extracted from AngryBird
http://www.codeandweb.com/texturepacker iPhone App displayed using
TexturePacker

20. Data from
Document / Library
Directory

21. Document / Library Directory
• It’s possible to extract unprotected files from Document directory on
an authorized computer using iTunes.
• It’s possible to extract unprotected files from Document / Library
directory using Tools like iExplorer even if device is locked.
• Hacker can jailbreak a device using softwares like redsn0w or
ac1dsnow even if device is locked.
• Extracting data from a jailbroken device is super easy.

22. Data Extraction using iExplorer
• Download iExplorer from: http://www.macroplant.com/iexplorer/
• Connect the target iDevice
• Browse to the Application whose data you want to extract under
• Apps > “App Name”, replace App Name with the target app name. In
this example we will be extract messages from Whatsapp iOS app.
• Whatsapp messenger stores imported Addressbook in Document
Directory by the name Contacts.sqlite and all conversations locally in
ChatStorage.sqlite
• You can export these files or any other files from Library Directory to a
folder.

23. Extracting Chats from Whatsapp
1. Export DB File from
Document Directory
2. Display Content on SQLite Manager

24. Sniffing
Network Traffic

25. Network Sniffing using Paros
• Download and Install Paros : http://www.parosproxy.org/
download.shtml
• Make sure your Mac and iDevice use same WiFi hotspot.
• Launch Paros. Go to Tools > Options > Local Proxy
• Set local proxy Address as the IP address of your mac and port
as 8080
• On your iDevice, select the WiFi network you are connected to and set
manual proxy with the above details. This direct the traffic of iDevice
through Paros.

26. Network Sniffing using Paros
1. Configuring Paros with
local IP on Port 8080
2. Configuring iPhone

27. Sniffing Instagram Traffic
• Instagram store photos taken by users on Amazon Web Server
• Whenever the app makes an internal API call either to get an user’s timeline or user’s own
photos, the application fetches photos from AWS using public URL.
• Using Paros you can sniff the network traffic and find out request parameters and responses
of such API calls.
• If you are sitting in a cafe which have public WiFI. Then you can capture packets and get
photos of everyone who are using the same network.
• For some apps you can even get username and password if those are being passed in clear
text or even if its base64 encoded.

28. Sniffing Instagram Traffic
API response
captured by Paros

29. Manipulating
Runtime

30. Libraries & Frameworks
• If you have ever wondered what are some of the libraries and
framework your favorite iOS applications are using. Then you can use
otool (object file displaying tool) to display object information
from its binary.
• http://goo.gl/o4EwT
• You can also find class interface of an app using class-dump-z. This
usually consists of the header file (.h) file of the application whose
information you’re extracting.
• http://code.google.com/p/networkpx/wiki/class_dump_z

31. Frameworks & Interfaces of apps

32. Breaking ObjC Codes
• As ObjC is a dynamic language that’s based on the principle of message passing.
It’s possible to inject custom code in a jailbroken device during runtime modifying
the content of a variable or method to perform malicious activities.
• On a jailbroken device you can install OpenSSH utility that will allow you to
login as root user to the target device.
• You can ssh to the target device using the command
root@<ip_address_of_device>. Default password is alpine
• After successfully logging into the device you can reverse engineer or modify the
runtime in gdb mode.

33. Abusing Runtime with Cycript
Using Cycript to manipulate runtime
Download Cycript from: http://www.cycript.org/

34. ObjC variables in runtime
1. Extracting Existing pin 2. Overwriting Existing pin.
of PhotoVault App from Now original user can not
its pinLock instance even access his own photos

35. Next Steps
• Start hacking your own apps and see if it’s easy to steal sensitive data
from those apps.
• Attend my talk on “Securing iOS Apps” at iOS Dev Scout # Sept
Meetup
• On 13th Sept 2012 (Thursday) at PlugIn@BLK71
• RSVP here: https://www.facebook.com/events/340285926062221/
• Go through the Books and Resources mentioned in next slides.

36. Books
Hacking and Securing iOS
iOS Hacker’s Handbook iPhone and iOS Forensics
Applications (Must Read)
By : Charlie Miller By : Andrew Hoog
By : Jonathan Zdziarski

37. •
Resources
Apple Reference Guides
• Security Overview
• Security Starting Point for iOS
• Keychain Service Programming Guide
• Secure Coding Guide
• Cryptographic Services Guide
• Certificate, Key,Trust Services Programming Guide
• Sample Codes
• Crypto Exercise : https://developer.apple.com/library/ios/samplecode/CryptoExercise/
CryptoExercise.zip
• Generic Keychain : https://developer.apple.com/library/ios/samplecode/GenericKeychain/
GenericKeychain.zip

38. iOS Conf SG - 2013
31st Jan : Workshop & Hands-on Sessions
1st & 2nd Feb : Conference
(15 Awesome Talks by renowned
iOS Authors, Bloggers, App Creators)
For Updates:
Join Our Facebook Group:
https://www.facebook.com/groups/iosdevscout/
Follow on Twitter: @iOSConfSG

39. Thank You
Subhransu Behera (Subh)
Twitter: @subhransu
Email: subh@subhb.org