Hacking and Securing iOS Apps : Part 1

This slide briefs about various tools & techniques you can use to extract unprotected data from iOS apps. You can extract resource files, database files, sniff data on network, get data in runtime using various methods describe in this slide. I will be talking more on App Security in my next talk in iOS Dev Scout meetup.

Transcript

1. Subhransu Behera (Subh) Twitter: @subhransu Email: subh@subhb.org Hacking & Securing iOS Apps @GeekCampSG 18th Aug 2012
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. User’s own iDevice running your APP other users running the same app other users running the same app other users running the same app File System Database Bundle System Data File System Database Bundle System Data Backend Server Database You need to protect data both on client and server side
7. Apple’s Security Model Kernel OS Partition Data Protection Class App Sandbox User Partition Encrypted File System Software Crypto Engine Device Key Group Key Apple Root Certificate Hardware and Firmware
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 Finder 2. Unarchive 3. Show Package 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. http://www.codeandweb.com/texturepacker Images extracted from AngryBird 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 of PhotoVault App from its pinLock instance 2. Overwriting Existing pin. Now original user can not 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 Applications (Must Read) By : Jonathan Zdziarski iOS Hacker’s Handbook By : Charlie Miller iPhone and iOS Forensics By : Andrew Hoog
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