Secure Your REST API (The Right Way)

We already showed you how to build a Beautiful REST+JSON, but how do you secure your API? At Stormpath we spent 18 months researching best practices, implementing them in the Stormpath API, and figuring out what works. Here’s our playbook on how to secure a REST API.

Sign up for Stormpath: https://api.stormpath.com/register
More from Stormpath: https://stormpath.com/blog

Transcript

1. Les Hazlewood @lhazlewood Apache Shiro PMC Chair CTO, Stormpath stormpath.com Secure your REST API (the right way)
2. .com • User Management and Authentication API • Security for your applications • User security workflows • Security best practices • Developer tools, SDKs, libraries
3. HTTP Authentication...
4. ... is all about the headers Learn more at Stormpath.com
5. 1. Request GET /accounts/x2b4jX3l31uiL HTTP/1.1 Host: api.acme.com Learn more at Stormpath.com
6. 2. Challenge Response HTTP/1.1 401 Unauthorized WWW-Authenticate: Basic realm=“name” Learn more at Stormpath.com
7. 3. Resubmit Request GET /accounts/x2b4jX3l31uiL HTTP/1.1 Host: api.acme.com Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ== Learn more at Stormpath.com
8. Authorization Header Format GET /accounts/x2b4jX3l31uiL HTTP/1.1 Host: api.acme.com Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ== Scheme Name Scheme-specific Value sp Learn more at Stormpath.com
9. 4. Successful Response HTTP/1.1 200 OK Content-Type: application/json ... { “email”: “jsmith@gmail.com”, “givenName”: “Joe”, “surname”: Smith”, ... } Learn more at Stormpath.com
10. Example: Oauth 1.0a GET /accounts/1234 HTTP/1.1 Host: api.acme.com Authorization: OAuth realm="Photos", oauth_consumer_key="dpf43f3p2l4k3l03", oauth_signature_method="HMAC-SHA1", oauth_timestamp="137131200", oauth_nonce="wIjqoS", oauth_callback="http%3A%2F%2Fprinter.example.com%2Fready", oauth_signature="74KNZJeDHnMBp0EMJ9ZHt%2FXKycU%3D" Learn more at Stormpath.com
11. Example: Oauth 2 GET /accounts/x2b4jX3l31uiL HTTP/1.1 Host: api.acme.com Authorization: Bearer mF_9.B5f-4.1JqM Learn more at Stormpath.com
12. Example: Oauth 2 MAC GET /accounts/x2b4jX3l31uiL HTTP/1.1 Host: api.acme.com Authorization: MAC id="h480djs93hd8", nonce="264095:dj83hs9s”, mac="SLDJd4mg43cjQfElUs3Qub4L6xE=" Learn more at Stormpath.com
13. Ok, now that’s out of the way • Please avoid Basic Authc if you can. • Favor HMAC-SHA256 digest algorithms over bearer token algorithms • Use Oauth 1.0a or Oauth 2 (preferably MAC) • Only use a custom scheme if you really, really know what you’re doing. Learn more at Stormpath.com
14. Status Codes Learn more at Stormpath.com
15. 401 vs 403 • 401 “Unauthorized” really means Unauthenticated “You need valid credentials for me to respond to this request” • 403 “Forbidden” really means Unauthorized “I understood your credentials, but so sorry, you’re not allowed!” Learn more at Stormpath.com
16. HTTP Authorization Learn more at Stormpath.com
17. HTTP Authorization • After authc, perform authz • Filter requests before invoking MVC layer • Blanket security policies • Per-URI customization Learn more at Stormpath.com
18. HTTP Authorization: OAuth • OAuth is an authorization protocol, NOT an authentication or SSO protocol. • “Can I see User X’s email address please?” NOT: • “I want to authenticate User X w/ this username and password” • People still try to use OAuth for authentication (OpenId Connect) Learn more at Stormpath.com
19. HTTP Authorization: OAuth • When OAuth 2 is a good fit: • If your REST clients do NOT own the data they are attempting to read • When Oauth 2 isn’t as good of a fit: • If your REST client owns the data it is reading • Could still be fine if you’re willing to incur some additional overhead Learn more at Stormpath.com
20. HTTP Authorization: JWT • JWT = JSON Web Token • Very new spec, but clean & simple • JWTs can be digitally signed and/or encrypted, and are URL friendly. • Can be used as Bearer Tokens and for SSO Learn more at Stormpath.com
21. Best Practices Learn more at Stormpath.com
22. API Keys Learn more at Stormpath.com
23. API Keys, Not Passwords • Entropy • Independence • Speed • Reduced Exposure • Traceability • Rotation Learn more at Stormpath.com
24. API Keys cont’d • Authenticate every request • Encrypt API Key secret values at rest. • Avoid Sessions (not RESTful) • Authc every request + no sessions = no XSRF attacks Learn more at Stormpath.com
25. Identifiers Learn more at Stormpath.com
26. Identifiers /accounts/x2b4jX3l31uiL Good Not So Good /accounts/1234 Why? Learn more at Stormpath.com
27. Identifiers • Should be opaque • Secure Random or Random/Time UUID • URL-friendly ‘Base62’ encoding • Avoid sequential numbers: • distribute ID generation load • mitigate fusking attacks Learn more at Stormpath.com
28. Query Injection Learn more at Stormpath.com
29. Query Injection Vulnerable URL: foo.com/accounts?acctId=‘ or ‘1’=‘1 String query = “select * from accounts where acct_id = ‘” + request.getParameter(“acctId”) + “’”; Solution • Use Parameterized Query API (Prepared Statements). • If not available, escape special chars Learn more at Stormpath.com
30. Redirects and Forwards Learn more at Stormpath.com
31. Redirects and Forwards • Avoid redirects and forwards if possible • If used, validate the value and ensure authorized for the current user. foo.com/redirect.jsp?url=evil.com foo.com/whatever.jsp?fwd=admin.jsp Learn more at Stormpath.com
32. TLS Learn more at Stormpath.com
33. TLS • Use TLS for everything • Once electing to TLS: – Never revert – Never switch back and forth • Cookies: set the ‘secure’ and ‘httpOnly’ flags for secure cookies • Backend/infrastructure connections use TLS too Learn more at Stormpath.com
34. TLS Cont’d • Configure your SSL provider to only support strong (FIPS 140-2 compliant) algorithms • Use Cipher Suites w/ Perfect Forward Secrecy! –e.g. ECDHE_RSA_WITH_AES_256_GCM_SHA256 • Keep your TLS certificates valid • But beware, TLS isn’t foolproof – App-level encryption + TLS for most secure results Learn more at Stormpath.com
35. Configuration Learn more at Stormpath.com
36. Configuration • CI: Security Testing • Security Patches • Regularly scan/audit • Same config in Dev, Prod, QA* – (Docker is great for this!) • Externalize passwords/credentials * Except credentials of course Learn more at Stormpath.com
37. Storage Learn more at Stormpath.com
38. Storage • Sensitive data encrypted at rest • Encrypt offsite backups • Strong algorithms/standards • Strong encryption keys and key mgt • Strong password hashing • External key storage • Encrypted file system (e.g. eCryptfs) Learn more at Stormpath.com
39. Thank You! • les@stormpath.com • Twitter: @lhazlewood • https://stormpath.com Learn more at Stormpath.com
40. .com • Free for developers • Eliminate months of development • Automatic security best practices Sign Up Now: Stormpath.com Learn more at Stormpath.com