Tizen Security

TIZEN SecurityHacking the New Mobile OS

05/03/2023 Intrepidus Group - Confidential

Mark Manning

• Sr. Security Consultant with Intrepidus Group• Mobile:

– Android– Windows Phone– Brew– iOS– Blackberry

• BSidesROC, Rochester 2600, Interlock Rochester

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Jason Ross

• Sr. Security Consultant with Intrepidus Group– Android– Web apps– Network

• Extra Curricular– TOOOL.ROC, DC585, BSidesROC– Security BSides*, Dragon Research Group


What we are going to tell you

What Tizen is & Where it might be going

The Tizen security model

How to perform Tizen security assessments

Predictions for the future

Tizen (/ˈtaɪzɛn/) is…

• An open source mobile operating system– Started life as Samsung SLP (then Bada), & Intel MeeGo– Governed by Linux Foundation

• Organized by a board of directors – The Tizen Association

• Supported by large companies– Intel, Samsung, Fujitsu

• Based on W3C standards for its applications– HTML5 APIs– Touch Events– Web Storage– WARP


Tizen wants to…

• Be the ubiquitous solution for “smart” consumer devices

• Release a high end device this year

• Grab a 15% market share of smartphones

• Replace Android as the most versatile operating system

• Be installed on:– Smart TV’s– Cars– Smart Phones– Tablets– Anything that is designed for high end user experience


Tizen Family Tree


Tizen History

• February 2010 – Nokia and Intel announce MeeGo– Nokia drops out of MeeGo in favor of Windows Phone

• September 2011 – Intel suspends MeeGo & announces Tizen as its replacement

• January 2012 – Tizen source code and SDK released

• May 2013 – Tizen 2.1 released

• July 2013 – Tizen 2.2 released

• August 2013 – Tizen IVI 3.0 beta released


Vapor Hardware

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Quick Comparison

Android iOS Firefox OS Ubuntu Tizen

Web App Support None None Yes Yes Yes

Native App Support Yes Yes No Yes Yes

Primary Application

Isolation Mechanism

Linux UIDs XNU /Seatbelt

B2G / Gecko

D-BUS / App Armor

SMACK labels

IDE Eclipse Xcode Good luck! Ubuntu SDK Eclipse

Application Signing Model

Developer Distributor Distributor Developer Distributor & Developer


Technical Steering Group

• In charge of development and working with OEMs (and advocacy)

• Consists of Samsung, Intel and now Huawei

• Coordinates development of the operating system


Tizen Association

• Always represented by 12 companies

• Always changing

• Current members:

http://www.fujitsu.com/

http://www.huawei.com/us/

http://www.intel.com/

http://www.kt.com/eng/main.jsp

http://www.uplus.co.kr/com/main/pemain/PeMain.hpi

http://www.nttdocomo.com/

http://www.orange.com/

http://www.panasonic.com/

http://www.samsung.com/

http://www.sktelecom.com/

http://www.sprint.com/

http://www.vodafone.com/content/index.html

http://www.vodafone.com/content/index.html


HTML5 Scores

APPLICATIONS


Tizen Application Stack


Types of Apps

• Web Applications: – Written in HTML5 – JavaScript makes calls to Privileged APIs– Supports libraries like jQuery Mobile– Can be either “Packaged Web Apps” or “Hosted Web Apps”

• Native Applications– C / C++– Native APIs unrelated to web app APIs– Focused on gaming

• Hybrid Applications– Little bit of both


WebRT

• WebRT is to Tizen what DalvikVM is to Android

• Execution of web applications

• Each application runs its own instance

• Access to device resources via JavaScript API

• Access control of web applications


The Widget Stack


Luckily Webkit is universally secure…


WGT

• Web applications or widgets

• W3C standard way of packaging an HTML5 application

• Zip archive with .wgt extension


Application Signing

• Each application is signed with 2 signatures– W3C Recommended way of handling widget signing– As opposed to Android’s one

• Author signature– The author of the application used to verify who created the app

• Distributer signature– from the publisher, or app store verifying where the application was

distributed from

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Privileged Device APIs

• Public: – Any developer can access – Example: Filesystem – access a location on the device

• Partner: – Only those developers that have been verified and approved can access it. – Partners are given a special Partner CA to sign their applications– Example: ApplicationManager – manage application certificates

• Platform– Reserved to OEMs and Tizen implementers– System level access to a device– Example: BluetoothAdapter

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config.xml File

• Similar to a manifest

• Declare Features: device capabilities

• Declare Privileges: API access required by the app

• Set policy: lets you set a “content security policy” for the application– White list the sites it should be connecting to– Based on W3C’s WARP


config.xml Example


Install Directory == Package Name


Installation Directory Structure

bin

APPID.AppName

res

wgt

shared

data

res

trusted

tmp

tmp



Encryption Support

• Web apps support encryption of Javascript, HTML, CSS, etc

• Install-time encryption only

• Key configuration is located in /usr/share/secure-storage/config– Usually points to /csa/.seckey

• Magic(key, wgt) = encryption

SMACK


SMACK - Introduction

• Linux Kernel Module

• Basis of the Tizen security sandbox model

• “Labels” are the metaphor– similar to how Android uses UIDs

• Tizen 2.1 has 41,000 SMACK rules– Tizen 3 is looking to reduce these


Smack - Control Mechanisms

• File control– Extended attributes (xattrs) give filesystem objects a label– The label corresponds to a SMACK rule

• IPC traffic

• Network traffic– A CIPSO header is attached to each network packet

• Processes– Can read /proc/self/attr/current to discover what SMACK labels they are running under


SMACK - Definitions

• Subject

• Object

• Access

• Label


SMACK - Access Rule Format

<subject-label> <object-label> <access-rule>


SMACK - Access Rule Examples

contacts-service _ arwxt

com.Intrepidus.pwn * arwx-

org.tizen.setting miracast-server rwx--

/opt/usr/apps/3FRIz5CoAw.Test = testApp/tmp/file.txt = myFiletestApp myFile r


Security Server

Application[Subject]

Resource[Object]

Smack Rulesets

SMACK – Access Request Process

/DEV/RANDOM


Content Security Framework

• McAfee contributed solution to a problem first noticed in Android– How does an app get access to the system to perform effective

scans?

• Provides API for anti-virus vendors– Low-level hooks into the system to bypass usual application

restrictions


Tizen Push Service

• Functionally similar to GCM on Android

• Messages limited to text data of 1024 bytes


ASLR

• “Fully implemented" in the Linux Kernel but some additional security measures are not currently implemented

Securiy protection Purpose

fstack-protector-all adds canary based buffer overflow checks on the stack and shuts down if it's corrupt

D_FORTIFY_SOURCE=2 replaces unbouncd string function calls with bounded ones. Done where GCC can determine the buffer size.

fpic, fpie position independent code for libraries (fpic) and executables (fpie). Protects against return to libc attacks

NX Bit No Execute bit


Weirdness

• Zypper is on the device• Install all the things!

• OpenSSH: Running by default on the device

• Root login is permitted

PERFORMING ASSESSMENTS


Attackers we are emulating

• A malicious application on the device

• A remote attacker that has hijacked another application’s backend

• Lost or stolen devices

Props to Katy Levinson/HackerDojo for this image


Attack Vectors

• Malicious application store / third party store– Helped out by the distributor signing model

• SMishing, phishing to install an application

• “Drive by” content (malicious ad networks)– Helped by defining WARP access tags or setting the

content-security-policy correctly


Tools

• Tizen SDK – Eclipse IDE

• Web simulator

• Tizen Device Emulator

• SDB


Tools - Tizen SDK IDE

• Eclipse based

• Comes with the Tizen device emulator

• And the web simulator


Tools - Web Simulator

• Lets you run aWGT inside of Google Chrome

• App assessment tool


Tools - Web Simulator Controls

• Allows you to manipulate the web simulator environment

• Contains functions to simulate device events

• Incoming calls / messages• Push messages• Orientation change• GeoLocation


Tools - Device Emulator

• Very similar to Android Emulator

• Create virtual devices and run them

• Devices are qemu VMs,– qcow format disk images


Tools - Device Emulator Configuration

• Change skin• Phone• General Purpose

• Configure RAM

• Control hardware acceleration


Tools - SDB

• Smart Development Bridge

• AKA:“It’s not ADB, we swear”


Definitely not ADB…


Using SDB + WRT to install apps


Assessment Methodology

• Static Analysis

• File System Analysis

• Dynamic Analysis

• Network Analysis


Static Analysis

• Improper permission requests– Overprivileged applications are a greater threat

• Unprotected shared content– SQLite databases– Temporary files with 777 access

• Encryption used– Custom encryption or built-in APIs?– Static keys saved in the application

• Cross origin access restrictions– Which domains are restricted


File System Analysis

• Storing information on the SDCARD

• Unrestrictive file permissions

• Temporary files with 777 permissions


Dynamic Analysis

• Sensitive file storage

• Overly permissive content sharing– Inter-application messaging– Shared SQLite database– Sensitive temp files


Network Analysis

• XSS means a privilege leakage– Similar to an Android permission hijack but with JavaScript

• Cross origin attacks– Can we evade the network restrictions

• SQLi (client side and server)– Parameterized queries are not used

• Handling untrusted server input– Testing both the web server and the web client in this model

• Secure data transport– SSL used throughout


Network MiTM Setup

• Set up a proxy in the WiFi Settings

• IPTables configuration

• Add CA certificates to the trusted system store

Trusted root certificate store

• Anything in /etc/ssl/certs that’s in PEM format and is named <8hexChars>.0 is considered a trusted cert

• So… openssl x509 -in burpCA.der -inform DER -out burpCA.pem -outform PEM

sdb push burpCA.pem /tmp/sdb shellsumv /tmp/burpCA.pem /etc/ssl/certs/ffffffff.0

Verification of Certificates

• Use the certificate viewer from to verify the certificate was “installed” correctly.


Review

• Applications– HTML5 / WebRT / Webkit– Privileged APIs

• SMACK– Subject / Object / Labels– 41K rules

• Assessments– IDE / SDK / Emulator / Simulator– Network MiTM


Predictions

• A Tizen phone will be released next year &adoption will be slow– It will be rooted within the first week

• Smart devices like cars, TV’s, and refrigerators will be pushed by Samsung

• A webkit exploit affecting Tizen will break their security model – This will cause devastating results to the platform, unlike any other mobile vulnerability

• Tizen will be adopted faster in non-American countries as a low cost, feature rich, alternative to Android


Questions


Contact

• [email protected]

• [email protected]

• http://intrepidusgroup.com/insight

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http://intrepidusgroup.com/insight

Technology

Tizen Security