Mobile Application Security

// …. and That’s all.

Ishan GirdharInfosec ConsultantAKS IT Services Pvt. Ltd

#Fact: 1Mobile devices have the

potential tobecome the biggest threat for

leakage ofconfidential information.

Overview

Part 1: Mobile Application Security

Part 2: Pentesting Mobile Application

Part 3: Owasp Top Ten Mobile Application Risk

Part 4: Case Study & Demonstrations.

Part 1:Mobile Application Security

Part 1: Overview

Introduction to Mobile Application Security.

Mobile Security Stack. Mobile Threat Model Modus Operandi for Mobile Application

Audit. Roadblocks Future of Mobile Application Security

Introduction to Mobile Security Modern mobile applications run on mobile devices

that have the functionality of a desktop or laptop running a general purpose operating system.

In this respect many of the risks are similar to those of traditional spyware, Trojan software, and insecurely designed apps.

Mobile devices are designed around personal and communication functionality which makes the mobile application and mobile security risks different from the top traditional computing risks.

Mobile Security Stack

Infrastructure Layer Lowest Layer Protocols▪ CDMA,GSM▪ GPS▪ SMS,MMS

 Hardware Layer Smartphone/Tablet Firmware

Operating System Layer Symbian S40/S60 Froyo,Gingerbread

Application Layer

Mobile Threat Model

Modus Operandi

1. Dynamic Analysis1. Debug the Running App (on device or in emulator)2. Analyze Network Traffic3. Analyze Remote Services (Http/SOAP/etc)

2. Static Anlysis1. Get Application

1. Extract application from device2. Receive application package from developers

2. Source code review3. Reverse engineering4. Disassembly5. Patching

… Apple & Android (Market Leader)

…Yes, Few Road Blocks as well.

Roadblocks

OWASP guidelines, procedures for testing are not yet available like Web applications.

Mobile application also includes vulnerabilities in the underlying architecture (OS & Vendor specific) unlike web application in which only application vulnerabilities are concerned.

Applications can use various modes of communications like SMS,MMS,EDGE, GPRS,3G and WiFi due to which security testing becomes difficult.

Simulator's have their own limitations: Can not simulate SMS communication (In case of communicating with SMS

Gateway ) though, they provide mechanism to send & receive sms between simulators.

Simulator’s don’t allow intercepting installed applications traffic. ( It has to be done, forcefully by interjecting an application into

running simulator to intercept network communication from that process)

…But, there is a Good News!!!

…Things are getting, Better!

Future: Mobile Application Security

There is A Lot More to come!!!

…and, yet More…

Part 2:Pentesting Mobile Application(Android)

Part 2: Overview

Pen testing Mobile Application – Android Background. Setting up the Test Environment. Setting up a proxy. Android Application Penetration Testing Toolkit. Reverse Engineering Android Applications File Permissions in android

Background

Android is a Linux based platform developed by Google and the open handset alliance.

Application programming for it is done exclusively in java.

The android operating system software stack consist of java applications running on a Dalvik virtual machine (DVK).

The current version as of august 2010 is 2.2. there are over 90,00 application available in the android market.

…Getting Ready for the audit

…Setting up Test Environment

There are several ways to test mobile application e.g: Using burp with a proxy. Using a phone emulator with a proxy. Using a phone to test and proxy outgoing phone

data to a PC. Requirements:

Computer running a Windows OS. Java 6 Eclipse SDk – Helios/Indigo Android 3.5 SDK Burp! Proxy

Mobile Audit: Where to start?

Setting up a Proxy…

If Application using is using HTTP(s), or is a website that you are testing on Android browser, the next step is to setup a proxy tool such as Burp!

There are 4 main ways of setting up such a proxy:

Method: First

Specify the proxy details when starting the emulator using the command below. This command is to use a proxy listening on port 8080

Emulator -avd testavd -http-proxy http://localhost:8080

Method: Second

The second option is to specify the proxy details in the emulator APN setting as shown below:

Home-> Menu-> Wireless & networks > Mobile Network -> Access Point Names

Update the following:

NAME: InternetAPN: InternetProxy: IP address of yourComputerUSERNAME: <N/A>PASSWORD:<N/A>

Method: Third

The third option is to specify it using the adb shell using the export command to set an environment variable, for example:

Export HTTP_PROXY=http://localhost:8080

Method: Four

Final alternative is by changing the proxy setting in the settings database from where the android web browser reads. The settings database uses SQLite.

Familiarity with basic SQL commands is recommended if your plan to use this method. Change the hostname and port information appropriately using the below command:

…Let’s Dive in!

Android Testing Tools Dynamic Analysis Tools▪ ADB▪ Manifest Explorer▪ Intent Sniffer▪ Busybox▪ Strace▪ Procrank

Static Analysis▪ Disassembly▪ Dex2jar▪ Baksmali

▪ Reverse Engineering▪ JD-GUI

Dynamic Analysis

1. ADB2. Manifest Explorer3. Intent Sniffer4. Busy box5. Strace6. Procrank

ADB

Android Debug Bridge: It is part of the Android SDK. It has it’s own shell, which allows you to execute linux commands such as ls –l . The android developer’s guide lists the full range of ADB commands but we highlight a few below:

ADB could be used to locate all the emulators and android devices connected to the computer to the computer using the command below:

adb devices

ADB

In our case the command found one instance of the emulator running. If multiple instances are running you can use the –s option in order to run commands against a specific device or emulator.

Adb –s emulator-5554 install Foobar.apk

Another important provided by the adb is to push or pull files to and from the device/Emulator.

Manifest Explorer

Every application running on android has an AndroidManifest.xml file. This file is very important from a security perspective as it defines the permission an application request. The Manifest Explorer tool is a utility that allows you to review this xml file with ease when testing it is important to verify that the application follows the principle of “Least privilege” and does not use permission that are ot required for it to function.

Manifest Explorer

Intent Sniffer

Intent is a mechanism in android to move data process. It forms the core of android’s Inter process Communication (IPC). Inetnts could indicate a number of actions such as startservice, sendbroadcast etc. The Intent Sniffer tool performs monitoring of Intents.

Busybox

Busybox provides some linux commands that could be useful during the penetration testing process. It extends the capability of android’s toolbox. In order to install busybox you can go through the following steps:

Download the busybox

Static Code Analysis

1. Disassembly1. Dex2jar2. Baksmali

2. Reverse Engineering1. Java Application Decompiler (JAD-

Gui)

Terminogies

Dissembler: is a computer program that translate machine language into assembly language ( The inverse operating of an assembler). A dissembler differs from a decompiler which targets a high level language rather than an assembly language.

Reverse Engineering: Reverse engineering involves reversing a program's machine code (the string of 0s and 1s that are sent to the logic processor) back into the source code that it was written in, using program language statements.

File Permissions in Android

Android file permission uses the same model as Linux, to check the permissions of a file, go to the ADB shell and type ls –l.

Every .apk file installed on the emulator has its own unique user ID.

This prevents one application from accessing the other application’s data, any file created by the application will be assigned that application’s user ID and will not normally accessible to other applications.

What about other, “killer Apps”?

..and yes, Android Malware’s.

Part 3:

Owasp Top 10 Mobile Application Risk’s.

Part 3: Overview

Owasp Top Ten Mobile Application Risk’s. M1: Insecure Data Storage M2: Weak Server Side Controls M3: Insufficient Transport Layer Protection M4:Client Side Injection M5: Poor Authorization & Authentication M6: Improper Session Handling M7: Security Decision Via Untrusted Inputs M8: Side channel Data Leakage M9: Broken Cryptography M10: Sensitive Information Disclosure.

Part 4:

Case Study & Demonstrations

Overview

Case Study: Facebook.apk : Pentesting a real world

Application

Demonstrations: Reverse Engineering a first Trojan for

Android Malware.

…Provide Some Resources

1. Anant Srivastav Bloghttp://anantshri.info/

2. Ankur BhargavaHttp://www.hakers.info/site/

3. http://www.veracode.com

Questions!!!