The Mobile Hacking CheatSheet

The Mobile Hacking CheatSheet is an attempt to summarise a few interesting basics info regarding tools and commands needed to assess the security of Android and iOS mobile applications.

PDF versions:

• Mobile Hacking Android CheatSheet
• Mobile Hacking iOS CheatSheet

Main Steps

1. Review the codebase
2. Run the app
3. Dynamic instrumentation
4. Analyze network communications

OWASP Mobile Security Testing Project

Mobile Security Testing Guide

https://github.com/OWASP/owasp-mstg

Mobile Application Security Verification Standard

https://github.com/OWASP/owasp-masvs

Mobile Security Checklist

https://github.com/OWASP/owasp-mstg/tree/master/Checklists

Android CheatSheet

APK Structure

• META-INF: Files related to the signature scheme (v1 scheme only)
• lib: Folder containing native libraries (ARM, MIPS, x86, x64)
• assets: Folder containing application specific files
• res: Folder containing all the resources files (layouts, strings, etc.) of the application
• classes.dex [classes2.dex] ...: Dalvik bytecode of the application
• AndroidManifest.xml: Manifest file describing essential information about the app (permissions, components, etc.)

Package Name

The package name represents the app’s unique identifier (e.g. for YouTube):

com.google.android.youtube

Data Storage

User applications

/data/data/<package-name>/

Shared Preferences Files

/data/data/<package-name>/shared_prefs/

SQLite Databases

/data/data/<package-name>/databases/

Internal Storage

/data/data/<package-name>/files/

adb

Connect throug USB

adb -d shell

Connect through TCP/IP

adb -e shell

Get a shell or execute the specified command

adb shell [cmd]

List processes

adb shell ps

List Android devices connected to your machine

adb devices

Dump the log messages from Android system

adb logcat

Copy local file to Android device

adb push <local> <device>

Copy file from the Android device

adb pull <remote> <local>

Install APK file on the Android device

adb install <APK_file>

Install an App Bundle

adb install-multiple <APK_file1> <APK_file2> <APK_file3> ...

Set-up port forwarding using TCP protocol from host to Android device

adb forward tcp:<local_port> tcp:remote_port

List all packages on the device

adb shell pm list packages

Find the path where the APK is stored for the selected package name

adb shell pm path <package-name>

List only installed apps (not system apps) and the associated path

adb shell pm list packages -f -3

List packages names matching the specified pattern

adb shell pm list packages -f -3 [pattern]

Application Signing

For signing your APK file, you have 2 options

• jarsigner: Only supports v1 signature scheme (JAR signature)

  jarsigner -verbose -keystore <keystore_name> -storepass <keystore_password> <APK_file> <alias_name>
  

• apksigner: Official tool from Android SDK (since version 24.0.3), which supports all the signature schemes (from v1 to v4)

  apksigner sign --ks <keystore_name> --ks-pass pass:<keystore_password> <APK_file> 
  

To create your own keystore, the following one-liner can be used:

keytool -genkeypair -dname "cn=John Doe, ou=Security, o=Randorisec, c=FR" -alias <alias_name> 
-keystore <keystore_name> -storepass <keystore_password> -validity <days> -keyalg RSA -keysize 2048 -sigalg SHA1withRSA

Code Tampering

To tamper an APK file, the foolowing steps should be performed:

1. Disassemble the app with apktool and save the smali code into output directory

   apktool d <APK_file> -o <directory_output>

2. Modify the smali code of your app (or the resource files if needed)

3. Build the modified APK with apktool

   apktool b <directory_output> -o <new_APK_file> 

4. Sign the APK (see Application Signing)

5. (Optional) Use zipalign to provide optimization to the APK file

   zipalign -fv 4 <input_APK> <output_APK>

Frida

Installation

Install Frida and Python bindings on your system using pip

pip install frida frida-tools

Download the Frida server binary matching the targeted architecture and your Frida version

VER=`frida --version`
ABI=`adb shell getprop ro.product.cpu.abi`
wget https://github.com/frida/frida/releases/download/$VER/frida-server-$VER-android-$ABI.xz
xz -d frida-server-$VER-android-$ABI.xz

Upload and execute the Frida server binary on your Android device (root privileges are needed)

VER=`frida --version`
ABI=`adb shell getprop ro.product.cpu.abi`
adb root
adb push frida-server-$VER-android-$ABI /data/local/tmp/frida
adb shell "chmod 755 /data/local/tmp/frida" 
adb shell "/data/local/tmp/frida"

Tools

List running processes (emulators or devices connected through USB)

frida-ps -U 

List only installed applications

frida-ps -U  -i

Attach Frida client to the specified application (emulator or device connected through USB)

frida -U <package_name>

Spawn the specified application (emulator or device connected through USB)

frida -U -f <package_name> 

Spawn the specified application without any pause at the beginning (emulator or device connected through USB)

frida -U -f <package_name> --no-pause

Load a Frida script when attaching to the specified application

frida -U -l <script_file> <package_name>

Objection

Inject Frida Gadget library inside an APK file by specifying the targeted architecture (if emulator not running or device not connected)

objection patchapk --source <APK_file> -V <frida_version> --architecture <arch>

Inject Frida Gadget library inside an APK file using lastest Frida version available on Github (if emulator running or device connected to the device)

objection patchapk --source <APK_file>

SSL/TLS Interception with BurpSuite

Before Android 7

1. Launch BurpSuite and modify Proxy settings in order to listen on "All interfaces" (or a specific interface)
2. Edit the Wireless network settings in your device or the emulator proxy settings (Android Studio)
3. Export the CA certificate from Burp and save it with ".cer" extension
4. Push the exported certificate on the device with adb (into the SD card)
5. Go to "Settings->Security" and select "Install from device storage"
6. Select for "Credentials use" select "VPN and apps"

References:

• Configuring an Android device to work with Burp
• Installing BurpSuite's CA certificate in an Android device

After Android 7

From Android 7, the Android system no longer trusts the user supplied CA certificates. To be able to intercept SSL/TLS communication, you have 3 options:

1. Use an older version of Android
2. Use a rooted device and install the BurpSuite CA certificate inside the sytem store certificate
3. Tamper the targeted application in order to re-enable the user store certificate

In order to tamper the targeted Android application, we are going to add or modify the network security configuration file. This file on recent Android versions allows to force the application to trust the user supplied CA certificates. The following steps should be performed:

1. Install the Burpsuite's CA certificate on your Android device (see Before Android 7)

2. Disassemble the targeted app (APK file) with apktool

3. Add or modify the network_security_config.xml file (usually on res/xml/ folder). The content of the file should be:

   <?xml version="1.0" encoding="utf-8"?>
   <network-security-config>
     <base-config>
       <trust-anchors>
         <certificates src="system" />
         <certificates src="user" />
       </trust-anchors>
     </base-config>
   </network-security-config>
   

4. If the network_security_config.xml file is not present on your app, the AndroidManifest.xmlalso need to be modified by adding the networkSecurityConfig tag as follow:

   <application android:name="AppName" android:networkSecurityConfig="@xml/network_security_config">

5. Build the modified app with apktool and then sign the newly created APK file (see Application Signing)

Content Provider

Query a Content Provider

adb shell content query --uri content://<provider_authority_name>/<table_name>

Insert an element on a Content Provider

adb shell content insert --uri content://<provider_authority_name>/<table_name> 
--bind <param_name>:<param_type>:<param_value>

Delete a row on a Content Provider

adb shell content delete --uri content://<provider_authority_name>/<table_name> 
--where "<param_name>='<param_value>'"

Activity Manager

Start an Activity with the specified Intent

adb shell am start -n <package_name/activity_name> -a <intent_action>

Start an Activity with the specified Intent and extra parameters

adb shell am start -n <package_name/activity_name> -a <intent_action> --es <param_name> <string_value> --ez <param_name> <boolean_value>  --ei <param_name> <int_value> …

iOS CheatSheet

Filesystem

App list database

/User/Library/FrontBoard/applicationState.db 

Binary directory: include all the static resources of the app

/private/var/containers/Bundle/Application/UUID/App.app 

Path of the binary (executable)

/private/var/containers/Bundle/Application/UUID/App.app/App

App metadata: configuration of the app (icon to display, supported document types, etc.)

/private/var/containers/Bundle/Application/UUID/App.app/Info.plist

Data directory

/private/var/mobile/Containers/Data/Application/Data-UUID

UUID (Universally Unique Identifier): random 36 alphanumeric characters string unique to the app Data-UUID: random 36 alphanumeric characters string unique to the app

Default password

By default the root password on your jailbroken iOS device is alpine

If you've changed it and want to reset it:

1. Open /etc/passwd or /private/etc/master.passwd with a file manager app (e.g. iFile/Fileza)
2. Change the hash to: /smx7MYTQIi2M
3. root password will be alpine

Bundle ID

The bundle ID (aka package name) represents the app’s unique identifier (e.g. for YouTube)

com.google.ios.youtube

How to find the data and binary directories

Grep is the not-so-quick ‘n dirty way to find where are the data and binary directories of your app

iPhone:~ root# grep -r <App_name> /private/var/*

How to find the data and binary directories and the Bundle ID

By launching Frida with the ios-app-info script

frida -U <App_name> -c dki/ios-app-info

And then

[iPhone::App]-> appInfo()

Or manually by opening the app list database

iPhone:~ root# sqlite3 /User/Library/FrontBoard/applicationState.db

And displaying the key_tab table to get the binary directories

sqlite> select * from key_tab;

Or displaying the application_identifier_tab table to get the bundle IDs

sqlite> select * from application_identifier_tab;

App decryption

1. Add https://level3tjg.xyz/repo/ src to Cydia and install bfdecrypt tool
2. Go to bfdecrypt pref pane in Settings and set the app to decrypt
3. Launch the app to decrypt: decrypted IPA is stored in the Documents folder of the app

Dynamic analysis with Frida

List running processes

frida-ps –U

Analyse the calls to a method by launching Frida with the objc-method-observer script

frida -U <App_name> –c mrmacete/objc-method-observer

And then using the command observeSomething

[iPhone::App]-> observeSomething('*[* *<Method_name>*]’);

Hook the calls to the method <Method_name>

frida-trace -U <App_name> -m "-[* <Method_name>*]"

Then open the JavaScript handler file to edit the onEnter or onLeave functions to manipulate the behavior of the app

Dynamic analysis with Objection

Inject objection

objection -g "<App_name>" explore

List the classes (output will contain thousands of lines)

ios hooking list classes

List the methods of a class

ios hooking list class_methods <Class_name>

Search for classes|methods names containing

ios hooking search classes|methods <String>

Analyse the calls to the method <Method_name>

ios hooking watch method "-[<Class_name> <Method_name>]"

Hook the <Method_name> and return true to each call

ios hooking set return_value "-[<Class_name> <Method_name>]" true

Get the NSLog (syslog)

Impactor (http://www.cydiaimpactor.com) let you display the NSLog (syslog) on command line

./Impactor idevicesyslog -u <UDID>

SSL Interception with BurpSuite

1. Launch Burp and modify proxy settings in order to listen on “All interfaces”
2. Browse to the IP/port of your Burp proxy using Safari
3. Tap on the “CA Certificate” at the top right of the screen
4. Tap on “Allow” on the pop-up asking to download a configuration profile
5. Go to “Settings->Profile Downloaded” and select the “PortSwigger CA” profile
6. Tap on “Install” then “Install” again and then “Install” one last time
7. Edit the wireless network settings on your device to set a proxy (“Settings->Wi-Fi” then tap on the blue “i”, slide to the bottom of the screen and tap on “Configure Proxy”)
8. Tap on ”Manual”, set the IP/port of your Burp proxy, tap on “Save”
9. Go to “Settings->General->About->Certificate Trust Settings” & toggle on the PortSwiggerCA

Bypass SSL Pinning using SSL Kill Switch 2

Download and install SSL Kill Switch 2 tweak

wget https://github.com/nabla-c0d3/ssl-kill-switch2/releases/download/0.14/com.nablac0d3.sslkillswitch2_0.14.deb
dpkg -i com.nablac0d3.sslkillswitch2_0.14.deb
killall -HUP SpringBoard 

Go to “Settings->SSL Kill Switch 2” to ”Disable Certificate Validation”

UDID (Unique Device Identifier)

UDID is a string that is used to identify a device. Needed for some operations like signature, app installation, network monitoring.

• Get the UDID with MacOS

idevice_id –l

or

ioreg -p IOUSB -l | grep "USB Serial"

or by launching Impactor without parameters

• Get the UDID with Linux

usbfluxctl list 

or

lsusb -s :`lsusb | grep iPhone | cut -d ' ' -f 4 | sed 's/://'` -v | grep iSerial | awk '{print $3}'

or by launching Impactor without parameters

Network capture (works also on non jailbroken devices)

• With MacOS (install Xcode and additional tools and connect the device with USB)

rvictl -s <UDID>
tcpdump or tshark or wireshark –i rvi0

• With Linux or Windows (get https://github.com/gh2o/rvi_capture and connect the device with USB)

./rvi_capture.py --udid <UDID> iPhone.pcap

Sideloading an app

Sideloading an app including an instrumentation library like Frida let you interact with the app even if it’s installed on a non jailbroken device.

With IPAPatch

Here’s the process to do it with IPAPatch: Clone the IPAPatch project

git clone https://github.com/Naituw/IPAPatch

Move the IPA of the app you want to sideload to the Assets directory

mv <IPAfile> IPAPatch/Assets/

Download the FridaGadget library (in Assets/Dylibs/FridaGadget.dylib)

curl -O https://build.frida.re/frida/ios/lib/FridaGadget.dylib

Select the identity to sign the app

security find-identity -p codesigning –v

Sign FridaGadget library

codesign -f -s <IDENTITY> FridaGadget.dylib

Then open IPAPatch Xcode project, Build and Run.

With Objection

Here’s the process to do it with Objection (detailed steps on https://github.com/sensepost/objection/wiki/Patching-iOS-Applications)

security find-identity -p codesigning –v
objection patchipa --source <IPAfile> --codesign-signature <IDENTITY>
unzip <patchedIPAfile>
ios-deploy --bundle Payload/my-app.app -W –d
objection explore

Data Protection Class

Four levels are provided by iOS to encrypt automatically files on the device:

• NSProtectionComplete: file is only accessible when device is unlocked (files are encrypted with a key derived from the user PIN code & an AES key generated by the device)
• NSProtectionCompleteUntilFirstUserAuthentication: (defaut class) same except as before, but the decryption key is not deleted when the device is locked
• ProtectedUnlessOpen: file is accessible until open
• NoProtection: file is accessible even if device is locked

Get Data Protection Class

By launching Frida with the ios-dataprotection script

frida -U <App_name> -c ay-kay/ios-dataprotection

License

The Mobile Hacking CheatSheet is an open source project released under the CC-BY-SA 4.0 licence.