Android Forensics. Presented By: Mohamed Khaled. Thanks to: Ibrahim Mosaad Mohamed Shawky

Transcription

1 Android Forensics Presented By: Mohamed Khaled Thanks to: Ibrahim Mosaad Mohamed Shawky

2 Agenda Mobile Forensic Process Different Mobile Forensic Scenario Acquisition Guide Challenges of Android Forensics How to Circumvent the Pass Code Types Of Analyses(Logical analysis) Types Of Analyses(Physical analysis) Android Partition Layout Custom Recovery Modifications How Data are Stored In Android Example of Useful Data extracted from Android Image 2

3 Mobile Forensic Process Receive device as evidence. Receive request for Intake Identify device specifications & capabilities examination Identify Goals of Examination Identification Prepare methods and tools to be used Prepare media and forensic workstation Preparation Protect the evidence Prevent for examination data destruction Prepare toolsremote to most recent version Isolation Isolate from the Cellular Conduct forensic acquisition network, bluetooth, and Wi-Fi Perform forensic analysis Processing Scan for malware Validate your acquisition Validate your forensic Verification findings Keep notes about your findings and process Documenting Draft and finalize your forensic reports Prepare exhibits Present Keep a gold copy of data in ayour Presentation findings safe place Keep data in common formats Archiving 3 for future

4 Data Acquisition Types Manual Logical Physical 4

5 scenarios The device might be found to be turned off after seizure. have internal or removable memory Locked /unlocked Have access via USB debug mode or not 6

6 Acquisition Guide A-(Unlocked) Airplane Mode SIM ID Cloning Isolate Device from the Network Take the necessary steps to ensure physical device access is possible Remove passcode Enable USB debugging Enable Stay Awake Disable timed screen lock features Acquire supporting media SIM card(s) Media cards Check associated media for device backups Physical Acquisitions 8

7 A1 - Isolate Device from the Network Airplane Mode Remove the SIM card. Place device in a shielded bag, box, tent, or room. 9

8 A 2-Ensure physical device access is possible Enable USB debugging Enable Stay Awake option Disable timed screen lock features 10

9 A3 - Physical Acquisitions Acquire supporting media SIM card(s) Media cards Check associated media for device backups(connected PC or Network) 11

10 Acquisition Guide B-(Locked) 1 Physical access requires that USB debugging mode is enabled. Forensic tools will use custom bootloaders to bypass the passcode if applicable. 2 Acquire supporting media SIM cards Media card(s) 3 Check associated computers and media for device backups Computers and media cards 12

11 Challenges of Android Forensics Access to system partitions is Restricted to The Android OS. Techniques for obtaining root privilege differ depending on Android version, device manufacturer and model. The OS has Authentication mechanisms that uses passwords, tactile patterns or biometric information 13

12 How to Circumvent the Pass Code The smudge attack Flash a New Recovery Partition (Our Solution) Know Gmail user name and password for the device JTAG and Chip-off 14

13 Types Of Analyses(Logical analysis) It is possible to backup all the present data in a cell phone without rooting Using Android Debug Bridge (adb backup command). $ adb backup -apk -shared -system -all -f %1.backup created a backup file which was later converted to.tar archive $ java -jar abe.jar unpack %1.backup %1.tar 15

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17 Physical Analysis (Low level analysis ) Low level analysis is based on exact, bit to bit, copy of userdata partition. After the copy, this partition is stored as a single file. which is later used as input for other analysis tools. Only a root user can make such a copy, so the phone must have been rooted at first. 19

18 What is rooting? Process of overcoming limitations imposed by manufacturers on smartphone or tablet owners. Gives an owner the ability to replace and/or alter system applications and settings Run applications requiring administrator-level privileges This includes listing active mounted partitions and cloning them 20

19 Physical analysis(recovery Mode) Another Way to Do Physical Analysis is by using Recovery Rom But first We Are Going to Talk About the Android Partition Layout 21

20 Android Partition Layout boot loader Splash Boot Recovery System Userdata or Data Cache Radio 22

21 Android Partition Layout (Cont.) boot loader: Stores the phone s boot loader program, which takes care of : Initializing the hardware when the phone boots Booting the Android kernel Implementing alternative boot modes such as download mode. boot: Stores the Android boot image, which consists of : Linux kernel(zimage) and the root file system ram disk (initrd). splash: Stores the first splash screen image seen right after powering on the device. 23

22 Android Partition Layout (Cont.) userdata (data): this is the device s internal storage for Application data User files such as: pictures, videos, audio, downloads. This is mounted as /data on a booted system. system: Stores the Android system image that is mounted as /system on a device. Contains the Android framework. Libraries. system binaries. pre-installed applications. 24

23 Android Partition Layout (Cont.) cache: Used to store various utility files such as : recovery logs and update packages downloaded over-the- air. On devices with applications installed on an SD card it may also contain the dalvik-cache folder, which stores the Dalvik Virtual Machine (VM) cache. 25

24 Physical analysis(recovery Mode) It is an operating designed to apply updates format the device perform other maintenance on the devices. The stock recovery mode on most devices is very basic Only provides a number of limited functions Does not provide root privileges in a shell. 26

25 Physical analysis(recovery Mode) Should use extreme caution when installing a custom recovery partition as the process often contains kernel and radio updates Could render the device unusable bricked. Extensive testing must be performed on a lab device first to ensure no issues occur. Examiners should understand what is being modified on the device during the installation of a custom recovery firmware. 27

26 Custom Recovery Rom Examples Cyanogenmod Recovery (clockworkmod) TeamWin (TWRP) 28

27 Custom Recovery Modifications We are going to modify in the Cyanogenmod source code The source code is writen in C Programming language. 29

28 Custom Recovery Modifications Remove Security Pattern The pattern file is at /data/system/gesture.key Other security pattern are in file /data/system/password.key We will also use the pre defined function system. Which will enable us to run Linux commands like ls,rm, etc system("rm /data/system/gesture.key"); //remove the pattern system("rm /data/system/password.key"); // remove any other lock like face or voice or password. 30

29 Custom Recovery Modification Physical imaging In order to do physical imaging you have to run command like dd if = /dev/sda1 of =/media/pc/file.dd Where if is the source(the media whci we want to image). The of is the destination So We have to know: the name of the driver of the source partition (i.e /data or /system) The name of the destination driver (USB Flash for example) 31

30 How To Know The Name Of The Driver For The Source Partition Using the file /etc/recovery.fstab We will search in the /etc/recovery.fstab till we find the driver name equivalent to the partition we want to image 32

31 Who to Know The name Of The Destination Driver (USB Flash for example) Vold: The volume manager daemon. Automatically Mount Sdcard and USB Flash memory (If connected) When Device Startup OR When Connected We are going to search in the Vold till we find USB or SdCard. 33

32 How Data are Stored In Android Android provides developers with five methods for storing data to a device Shared preferences Internal storage External storage SQLite Network 34

33 How Data are Stored In Android(Shared preferences) Allow a developer to store key-value pairs of primitive data types in a lightweight XML format. /data/data/<com.android.contacts>/shared_prefs Used to set the programs configuartion 35

34 How Data are Stored In Android (Internal storage) Contain more complicated data structures. The files are stored in the application s /data/data subdirectory. Files can only be read by the application. Indicate data that may be of interest to a forensic analyst 36

35 How Data are Stored In Android (External storage) Files stored on the internal device s storage have strict security and location parameters. Files on the various external storage devices have far fewer constraints. Emulated SdCard and Actual SdCard Examples Pictures,Videos,,etc 37

36 How Data are Stored In Android (SQLite) Databases are used for structured data storage SQLite is a popular database format appearing in many mobile systems traditional operating systems. /data/data/<packagename>/databases. SQLite databases are a rich source of forensic data. 38

37 How Data are Stored In Android (Network) Very few applications took advantage of the network as a storage option. The Android Developer web site provides very few details for those interested in network storage. You can use the network (when it is available) to store and retrieve data on your own web-based services. Dropbox Google Drive Onedrive 39

38 Example of Useful Data extracted from Android Image Android Browser Password / data/data/com.android.browser/databases/webview.d b.table select * from password; data/com.android.chrome/app_chrome/default/login Open Login Data file using txt viewer /data/misc/wifi/ Open wpa_supplicant.conf file using txt viewer. 40

39 References Android Forensics by Andrew Hoog Android Hacker's Handbook Joshua J. Drake,Pau Oliva Fora,Zach Lanier,Collin Mulliner,Stephen A. Ridley andgeorg Wicherski Developing Process for Mobile Device Forensics Cynthia A. Murphy Android Forensics, Part 1: How we recovered (supposedly) erased data