Security Best Practices for Mobile DevelopmentMobile SDK Entity Framework and SmartStore

Tom Gersic, Salesforce.comDirector, Mobile Services Delivery@tomgersic

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Tom GersicDirector, Mobile Services Delivery@tomgersic

Agenda• Fundamental Principles• What iOS and Android Share• iOS Specific Characteristics• Android Specific Characteristics• Salesforce Mobile Offerings

Who thinks the data on their phone is secure?

Fundamental Security Principles

Vulnerability

Threat

Consequence

Mitigation

Separation of Concerns – Principle of Least Privilege

Security Stack

Real life examples

Libtiff Image Exploit / Jailbreak• iPhone 1 – patched in 1.1.2• Tiff buffer overflow• No DEP/ASLR – nothing to

prevent executing code on the heap• Gained root access from viewing an

image on the web

ASLR (PIE) and DEP

iOS 7 Lock Screen Bypass

Fingerprint Hacking

“Bluebox Uncovers Android Master Key -- 2013”

Concatenated SMS Exploit – Charlie Miller

Concatenated SMS Exploit• Takes 519 SMS messages – all but 1 is invisible• Send message -1 of X to underflow the array buffer• Can’t be stopped by the user• Used to write an entire binary executable to the heap, and run

it, taking over the phone.

NFC Exploit

But most of the time…

Data Security – Hardware EncryptionRequires PIN/Passcode on both iOS and AndroidOn iOS, apps opt-inSupported on

▪ iPhone 3GS w/ iOS v4+ (AES 256 bit)▪ Android Honeycomb+ (AES 128 bit)

• Some manufacturers increase to AES 256 bit (Samsung SAFE)

SD Card encryption on Android is manufacturer specific.

Is Facebook.app Secure?

App Security

Layers of Defense

Application Signing

Application Sandboxing

iOS Sandbox• All apps (Apple’s and App Store) run as “mobile” user.• Sandboxing is bolted on -- handled via XNU Sandbox

“Seatbelt” kernel extension.• Applications run in separate subdirectories of

/private/var/mobile/Applications• Any app in this directory is loaded with “container”

(sandboxed) profile.

Android Sandbox• Uses underlying Linux security model• Every app runs as a separate user• Apps signed by the same developer can run as the same user, if

desired (not the default, though)• Every app runs in its own instance of the Android Runtime (Dalvik

Virtual Machine)• Like iOS, every app has its own directory structure• SD Card, though, is generally public – accessible to all apps and

unencrypted unless manufacturer has added encryption (Samsung SAFE)

Background Processing• iOS 6:

• Audio Streaming (Spotify, Pandora)• GPS / Navigation• VOIP• Newsstand app content downloading• Hardware integrations (bluetooth, other external accessories)

• iOS 7• 10 3 minute window after app closes to finish any task.• Background Fetch• Remote Notifications• Background Transfer Service

iOS 7 Backgrounding

Background Processes / App Interaction

Types of Android Components

▪ Activities▪ Intent▪ Service▪ Content Provider▪ Broadcast Receiver

Public / Private Components

But what about custom keyboards?

Keyboard Security Risks

Except Passwords?

https://github.com/tomgersic/AndroidKeyLogger

Permissions

Mitigation

Static Analysis Tools

Application Encryption• Encrypt your data yourself using PIN / Passcode• CoreData/SQLCipher

▪ NSIncrementalStore▪ Good Dynamics

• FMDB/SQLCipher▪ Salesforce Smartstore

Jailbreak Detection• Sandbox integrity check: fork() should fail• Check for jailbreak files:

▪ /Applications/Cydia.app▪ /Library/MobileSubstrate/MobileSubstrate.dylib▪ /var/cache/apt▪ /bin/sh▪ /bin/bash

In-App Encryption

SmartStore Stack

Enable ASLR in Your App• ASLR: Address Space Layout Randomization

Stack Canaries• AKA Stack Smashing Protection• Protect against buffer overflows• Places random known value (canary) before local variables• Use Apple LLVM – won’t work with LLVM GCC

Hide Data from App Snapshot Images

Who STILL thinks the data on their phone is secure?

Tom Gersic

Director, Mobile Services Delivery@tomgersic

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