Security and Authentication in React Native

Kadi Kraman / Formidable

@kadikraman

Kadi Kraman

Senior React Native Engineer

@kadikraman

Formidable

@kadikraman

Kadi Kraman

Senior Software Engineer

Web Developer

...who writes mobile apps now, because we can do it in JavaScript (thanks, Facebook)

Secrets

How to keep them safe?

If the user shouldn't see it,

1. Do not send it via a network request

2. Do not ship it in the app code

3. Do not save it in Async Storage

3Fun Security Fail

Alternative dating app leaking their members' sensitive info

(August, 2019)

Users' real time location...

Private photos...

But that will never happen to me!

...right?

  Mary Strawberry

react, react native, prosecco

 I like long walks on the beach and puppies

Public

Paul Pear

Protected

Private

/api/users

[
  {	
    id: 123,
    firstName: "Mary",
    lastName: "Strawberry"
    avatar: "https://some.url/mary.png",
    email: "mary.strawberry@fakemail.com",
    phone: "123456789",
    interests: ["react", "react native", "prosecco"],
    bio: "I like long walks on the beach and puppies"
  },
  {
    id: 234,
    firstName: "Paul",
    lastName: "Pear",
    avatar: "https://some.url/paul.png"
  }
]

Public, Protected, Private

Sensitive info should always be filtered server-side

How easy is it really to see your mobile app traffic?

You will need...

Phone (iPhone 6s)

Laptop (MacBook Pro)

Proxy app (Charles Proxy)

WiFi

DO try this at home! 🏠

1. Download and install Charles Proxy

2. Configure mobile traffic to go through the proxy

3. Install the Charles Proxy SSL cert on your phone

4. Enable SSL proxying for all hosts

Slack

LinkedIn

Virgin Active

Do not add sensitive info in your app source code

How does she do it?

1. Get the public .apk for each new version of the app

 

2. Decompile the app code using a publicly available tool (and a custom python script)

 

3. Read through the code to see what's changed

Async Storage

Simple, unencrypted, asynchronous, persistent, key-value storage system that is global to the app

 

It should be used instead of LocalStorage

Async Storage

Use for non-sensitive app info

Persisted app state - YES

Auth tokens - NO

Async Storage is sandboxed for each app

However this is an OS restriction, which can be overcome

Rooting/Jailbreaking devices

Rooting (Android)

obtaining root access to device

Jailbreaking (iOS)

privilege escalation of an Apple device for the purpose of removing software restrictions imposed by Apple

If the user shouldn't see it,

1. Do not send it via a network request

2. Do not ship it in the app code

3. Do not save it in Async Storage

Recap!

So where can you store tokens?

Android Shared Preferences

iOS Keychain

The info should still be encrypted, because jailbroken devices will be able to access it in plaintext

Security tips

1. Do calculate permissions server-side

2. Do only send the user data they're allowed to see

3. Do use secure storage, e.g.

  • react-native-sensitive-info or
  • react-native-keychain

for tokens and other sensitive info

Authentication

OAuth 2 !== OpenID

OAuth 2

OpenID

Open standard and decentralized authentication protocol

Allows users to be authenticated by co-operating sites

OpenID Connect - authentication layer that sits on top of the OAuth 2.0 authorization framework

Potential Security concerns with OAuth2 on Native Apps

POST

/authorize?
  clientId=<my_id>&
  redirectUri=<my_redirect_uri>&
  scope=<access_scope>

1. Ask the user to authenticate

2. After a successful login, the provided redirect uri is called together with an verification code

3. verification code is exchanged for an auth token

POST

/token?
  clientId=<my_id>&
  code=<code>
POST

/authorize?
  clientId=<my_id>&
  redirectUri=<my_redirect_uri>&
  scope=<access_scope>
  

1. Ask the user to authenticate

2. After a successful login, the provided redirect uri is called together with an verification code

3. verification code is exchanged for an auth token

POST

/token?
  clientId=<my_id>&
  code=<code>&
  clientSecret=<secret>
POST

/authorize?
  clientId=<my_id>&
  redirectUri=<my_redirect_uri>&
  scope=<access_scope>
  

1. Ask the user to authenticate

2. After a successful login, the provided redirect uri is called together with an verification code

3. Verification code is exchanged for an auth token

POST

/token?
  clientId=<my_id>&
  code=<code>

Web addresses are unique, app schemes are not

The attacker can intercept the verification code and use it to obtain the auth token

PKCE ("pixy") to the rescue!

Security extension to OAuth 2.0 for public clients on mobile devices

Designed to prevent interception of the authorisation code by a malicious application that has sneaked into the same device

Proof Key for Code Exchange

POST

/authorize?
  clientId=<my_id>&
  redirectUri=<my_redirect_uri>&
  scope=<access_scope>&
  code_challenge=<generated_code_challenge>&
  code_challenge_method=<method_used>

1. Ask the user to authenticate

2. After a successful login, the provided redirect uri is called together with an verification code

3. verification code is exchanged for an auth token

POST

/token?
  clientId=<my_id>&
  code=<code>&
  code_verifier=<generated_code_verifier>
POST

/authorize?
  clientId=<my_id>&
  redirectUri=<my_redirect_uri>&
  scope=<access_scope>&
  code_challenge=<generated_code_challenge>&
  code_challenge_method=<method_used>

1. Ask the user to authenticate

2. After a successful login, the provided redirect uri is called together with an verification code

3. verification code is exchanged for an auth token

POST

/token?
  clientId=<my_id>&
  code=<code>&
  code_verifier=<generated_code_verifier>
const sha256 = (buffer) =>
  crypto
   .createHash('sha256')
   .update(buffer)
   .digest();

const challenge = base64URLEncode(sha256(verifier));
POST

/authorize?
  clientId=<my_id>&
  redirectUri=<my_redirect_uri>&
  scope=<access_scope>&
  code_challenge=<generated_code_challenge>&
  code_challenge_method=<method_used>

1. Ask the user to authenticate

2. After a successful login, the provided redirect uri is called together with an verification code

3. Verification code is exchanged for an auth token

POST

/token?
  clientId=<my_id>&
  code=<code>&
  code_verifier=<generated_code_verifier>

Cryptographically random key that was used to generate the code_challenge passed to /authorize.

const sha256 = (buffer) =>
  crypto
   .createHash('sha256')
   .update(buffer)
   .digest();

const challenge = base64URLEncode(sha256(verifier));

React Native App Auth

Thank you!

Unsplash photos by @wflwong @jonah_jpg @jonaselia @markusspiske

Authentication and Security in React Native

By Kadi Kraman

Authentication and Security in React Native

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