In this presentation, Java Developer Evangelist Micah Silverman demystifies HTTP Authentication and explains how the Next Big Thing - Token Authentication - can be used to secure web applications on the JVM, REST APIs, and 'unsafe' clients while supporting security best practices and even improving your application's performance and scale. Topics Covered: Security Concerns for Modern Web Apps Cross-Site Scripting Prevention Working with 'Untrusted Clients' Securing API endpoints Cookies Man in the Middle (MitM) Attacks Cross-Site Request Forgery Session ID Problems Token Authentication JWTs Working with the JJWT library End-to-end example with Spring Boot

1. Securing Web Applications
with Token Authentication
Micah Silverman @afitnerd
Co-Author, Mastering Enterprise JavaBeans 3.0
Java Developer Evangelist, Stormpath

2. About Stormpath
• Authentication & User Management API
• Hosted data store w/ advanced crypto
• Centralize user login across your applications
• Multi-tenant support for your SaaS
• Active Directory, LDAP, social connections
• API authentication & token authentication
• Supported, Free tier for developers

3. Overview
• Security Concerns for Modern Web Apps
• Cookies: need to know
• Session ID Problems
• Token Authentication to the rescue!
• OAuth2 & Java Example

4. Security Concerns for Modern Web Apps
• SPAs and Mobile apps are ‘Untrusted Clients’
• Prevent malicious code
• Secure user credentials
• Secure server endpoints (API)
• Expose Access Control rules to the Client

5. Prevent Malicious Code
• Cross-Site Scripting (XSS) attacks are a real,
huge threat

6. Prevent Malicious Code
Cross-Site Scripting (XSS) attacks
https://www.owasp.org/index.php/XSS

7. XSS Attack
Demo
https://www.google.com/about/appsecurity/
learning/xss/#BasicExample

8. XSS Attack – What Can I Do?
Read EVERYTHING on this page:
https://www.owasp.org/index.php/XSS
And then do these things:
https://www.owasp.org/index.php/
XSS_(Cross_Site_Scripting)_Prevention_Cheat_Sheet

9. XSS Attack – What Can I Do?
Escape Content!
Dynamic HTML: use well-known, trusted
libraries. Do NOT roll your own.
DOM attacks: escape user input

10. XSS Attack – What Can I Do?
SPAs: frameworks like Angular probably do a lot
of work for you (e.g. preventing DOM attacks by
escaping user input).
You should still read up on it.

11. Secure User Credentials
• Traditionally, we have used Session IDs
• This is OK, as long as you do cookies ‘right’
• Authentication Tokens are better ☺ (more
on this later)

12. Overview
• Security Concerns for Modern Web Apps
• Cookies: need to know
• Session ID Problems
• Token Authentication to the rescue!
• Java Example

13. Session ID Cookies

14. Secure Server (API) Endpoints
• Traditionally use Session ID Cookies
• Session ID à Session à User identity
• Use framework like Apache Shiro or Spring
Security to assert security rules

15. Expose Access Control Rules to the Client
• Traditional solution:
• Session ID à Session à User data in your DB
• Provide a /me or /profile endpoint
• Access Tokens are better!

16. Let’s talk about cookies...

17. Cookies are OK! If you do them correctly
Cookies can be easily compromised:
• Man-in-the-Middle (MITM) attacks
• Cross-Site Request Forgery (CSRF)

18. Someone ‘listening on the wire’ between the
browser and server can see and copy the
cookie.
Solutions
• Use HTTPS everywhere
• TLS everywhere on internal networks

19. Cross-Site Request Forgery (CSRF)
"... occurs when a malicious web site, email,
blog, instant message or program causes a
user’s web browser to perform an unwanted
action on a trusted site for which the user is
currently authenticated"
https://www.owasp.org/index.php/
CrossSite_Request_Forgery_(CSRF)_Prevention_Cheat_Sheet

20. Cross-Site Request Forgery (CSRF)
Attacker enables a user to request your server.
Example:
<a href="https://yoursite.com/
transferMoney?to=BadGuy&amount=10000">
See Cute Cats!
</a>
What happens?

21. Cross-Site Request Forgery (CSRF)
• The attacker cannot see your cookie values, BUT:
• The browser says, "The request is going to your
server, so I’ll happily send you your cookies."
• Your server transfers the money because it ‘sees’ a
valid, non-expired session id cookie for an
authenticated session.

22. Cross-Site Request Forgery (CSRF)
Solutions
• Synchronizer Token
• Double-Submit Cookie
• Origin header check

23. Synchronizer Token – Trusted Page

24. Synchronizer Token – Foreign Page

25. Synchronizer Token - Considerations
• Requires cooperation from your rendering
layer
• Requires you to store tokens in a data store
or cache
• Difficult to do with static SPA content
• Only protects against forged POST requests,
not GET requests!
Pro tip: never allow GETs to modify server state!

26. Double Submit Cookie
• Send two cookies: Session ID + Random
Value
• Send random value explicitly, browser Same-
Origin-Policy
• Best Way: send as a custom header

27. Double Submit Cookie

28. Double Submit Cookie Considerations
• Custom HTTP header, do what makes sense
for your app
• Still vulnerable to XSS - Random Value still
accessible to the JS environment.
• Protect against XSS!

29. Origin header check
• Browsers send Origin header
• Header value is the domain of the page
initiating the request
• Cannot be hacked via browser JS
(could still be modified by a malicious HTTP proxy
server)

30. Overview
• Security Concerns for Modern Web Apps
• Cookies: need to know
• Session ID Problems
• Token Authentication to the rescue!
• Java Example

31. Session ID Problems
• They’re opaque and have no meaning
themselves (they’re just ‘pointers’).
• Service-oriented architectures might need a
centralized ID de-referencing service

32. Session ID Problems
• Opaque IDs mean clients can’t inspect them
and find out what it is allowed to do or not - it
needs to make more requests for this
information.

33. Session ID Problems
• Sessions = Server State!
• You need to store that state somewhere
• Session ID à look up server state on *every
request*.
• Really not good for distributed/clustered apps
• Really not good for scale

34. Overview
• Security Concerns for Modern Web Apps
• Cookies: need to know
• Session ID Problems
• Token Authentication to the rescue!
• Java Example

35. Token Authentication
• What is Authentication?
• What is a Token?

36. JSON Web Tokens (JWT)
• A URL-safe, compact, self-contained string with
meaningful information that is usually digitally
signed or encrypted.
• The string is ‘opaque’ and can be used as a
‘token’.
• Many OAuth2 implementations use JWTs as
OAuth2 Access Tokens.

37. JSON Web Tokens (JWT)
• You can store them in cookies! But all those
cookie rules still apply.
• You can entirely replace your session ID with
a JWT.

38. JSON Web Tokens (JWT)
In the wild they look like just another ugly string:
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJ
pc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQo
gImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnV
lfQ.dBjftJeZ4CVPmB92K27uhbUJU1p1r_wW1gFWFOEj
Xk

39. JSON Web Tokens (JWT)
In the wild they look like just another ugly string:
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJ
pc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQo
gImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnV
lfQ.dBjftJeZ4CVPmB92K27uhbUJU1p1r_wW1gFWFOEj
Xk

40. JSON Web Tokens (JWT)
In the wild they look like just another ugly string:
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJ
pc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQo
gImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnV
lfQ.dBjftJeZ4CVPmB92K27uhbUJU1p1r_wW1gFWFOEj
Xk

41. JSON Web Tokens (JWT)
But they do have a three part structure. Each
part is a Base64-encoded string:
eyJ0eXAiOiJKV1QiLA0KICJhb
GciOiJIUzI1NiJ9
.
eyJpc3MiOiJqb2UiLA0KICJle
HAiOjEzMDA4MTkzODAsDQogIm
h0dHA6Ly9leGFtcGxlLmNvbS9
pc19yb290Ijp0cnVlfQ
.
dBjftJeZ4CVPmB92K27uhbUJU
1p1r_wW1gFWFOEjXk
Header
Body
(‘Claims’)
Cryptographic
Signature

42. JSON Web Tokens (JWT)
Base64-decode the parts to find the juicy bits:
{
"typ":"JWT",
"alg":"HS256"
}
{
"iss":"http://trustyapp.com/",
"exp":
1300819380,
"sub":
"users/8983462",
"scope":
"self
api/buy"
}
tß´—™à%O˜v+nî…SZu¯ˉµ€U…8H×
Header
Body
(‘Claims’)
Cryptographic
Signature

43. JSON Web Tokens (JWT)
The claims body is the best part! It can tell:
{
"iss":"http://trustyapp.com/",
"exp":
1300819380,
"sub":
"users/8983462",
"scope":
"self
api/buy"
}
Who
issued
the
token

44. JSON Web Tokens (JWT)
The claims body is the best part! It can tell:
{
"iss":"http://trustyapp.com/",
"exp":
1300819380,
"sub":
"users/8983462",
"scope":
"self
api/buy"
}
Who
issued
the
token
When
it
expires

45. JSON Web Tokens (JWT)
The claims body is the best part! It can tell:
{
"iss":"http://trustyapp.com/",
"exp":
1300819380,
"sub":
"users/8983462",
"scope":
"self
api/buy"
}
Who
issued
the
token
When
it
expires
Who
it
represents

46. JSON Web Tokens (JWT)
The claims body is the best part! It can tell:
{
"iss":"http://trustyapp.com/",
"exp":
1300819380,
"sub":
"users/8983462",
"scope":
"self
api/buy"
}
Who
issued
the
token
When
it
expires
Who
it
represents
What
they
can
do

47. JSON Web Tokens (JWT)
Great! Why is this useful?
• Implicitly trusted because it is cryptographically
signed (verified not tampered).
• It is structured, enabling inter-op between services
• It can inform your client about basic access control
rules (permissions)*
• And the big one: statelessness!
*servers must always enforce access control policies

48. JSON Web Tokens (JWT)
So, what’s the catch?
• Implicit trust is a tradeoff – how long should
the token be good for? how will you revoke it?
(Another talk: refresh tokens)
• You still have to secure your cookies!
• You have to be mindful of what you store in
the JWT if they are not encrypted. No
sensitive info!

49. How do you do it on the JVM?
JJWT is awesome
https://github.com/jwtk/jjwt

50. How do you do it on the JVM?
import io.jsonwebtoken.Jwts;
import io.jsonwebtoken.SignatureAlgorithm;
byte[] key = getSignatureKey();
String jwt =
Jwts.builder().setIssuer("http://trustyapp.com/")
.setSubject("users/1300819380")
.setExpiration(expirationDate)
.put("scope", "self api/buy")
.signWith(SignatureAlgorithm.HS256,key)
.compact();
Create
a
JWT:

51. How do you do it on the JVM?
Verify
a
JWT:
try {
Jws<Claims> jwtClaims =
Jwts.parser().setSigningKey(key).parseClaimsJws(jwt);
//OK, we can trust this JWT
} catch (SignatureException e) {
//don't trust the JWT!
}

52. How do you get a Token?

53. Example: your SPA, your server

54. 1. Token Request
POST /oauth/token HTTP/1.1
Origin: https://foo.com
Content-Type: application/x-www-form-urlencoded
grant_type=password&username=username&password=p
assword
*Assert
allowed
origin
for
browser-­‐based
apps

55. 2. Token Response
HTTP/1.1 200 OK
Content-Type: application/json;charset=UTF-8
Cache-Control: no-store
Pragma: no-cache
{
"access_token":"2YotnFZFEjr1zCsicMWpAA...",
"token_type":"example",
"expires_in":3600,
"refresh_token":"tGzv3JOkF0XG5Qx2TlKWIA...",
"example_parameter":"example_value"
}

56. 3. Resource Request
GET /admin HTTP/1.1
Authorization: Bearer 2YotnFZFEjr1zCsicMW...

57. Example: Token Request using an API Key
POST /token HTTP/1.1
Content-Type: application/x-www-form-urlencoded
grant_type=client_credentials&client_id=apiKeyId&clie
nt_secret=apiKeySecret
*Assert
allowed
origin
for
browser-­‐based
apps

58. Demo!

59. Thanks!
@afitnerd @goStormpath
• Token Authentication for Java, JEE, Spring and Spring Boot
• Free Supported Developer Tier
• Elegant API
• OSS Java SDKs + Tutorials
Get a Free-Forever Account: Stormpath.com