The State of OAuth Aaron Parecki Senior Security Architect, Okta Interface API Days • June 2020 

@aaronpk June 2020 oauth.net/2 

@aaronpk June 2020 The State of OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials Grant Types 

@aaronpk June 2020 

@aaronpk June 2020 The State of OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials Grant Types RFC6750 Bearer Tokens Token Usage Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String 

@aaronpk June 2020 

@aaronpk June 2020 OAuth Server OAuth Client Passing Data via the Front Channel Did they catch 
 it? Did someone else 
 steal it? Is this really 
 from the real 
 OAuth server? 

@aaronpk June 2020 The State of OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials RFC6750 Bearer Tokens RFC7636 +PKCE Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String 

@aaronpk June 2020 The State of OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials RFC6750 Bearer Tokens RFC7636 +PKCE RFC8252 PKCE for mobile Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String 

@aaronpk June 2020 The State of OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials RFC6750 Bearer Tokens RFC7636 +PKCE RFC8252 PKCE for mobile Browser App BCP PKCE for SPAs Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String 

@aaronpk June 2020 

@aaronpk June 2020 https://example.com https://app.example.com https://auth.example GET / HTML, CSS, etc POST /token access token CORS 

@aaronpk June 2020 caniuse.com/cors 

@aaronpk June 2020 The State of OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials RFC6750 Bearer Tokens RFC7636 +PKCE RFC8252 PKCE for mobile Browser App BCP PKCE for SPAs Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String 

@aaronpk June 2020 The State of OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials RFC6750 Bearer Tokens RFC7636 +PKCE RFC8252 PKCE for mobile Browser App BCP PKCE for SPAs Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String 

@aaronpk June 2020 OAuth 2.0 for Browser-Based Apps 

@aaronpk June 2020 OAuth 2.0 for Browser-Based Apps 

@aaronpk June 2020 The State of OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials RFC6750 Bearer Tokens Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String RFC7636 +PKCE RFC8252 PKCE for mobile Browser App BCP PKCE for SPAs PKCE for confidential clients Security BCP 

@aaronpk June 2020 Password oauth.net/2/oauth-best-practice 

@aaronpk June 2020 Password oauth.net/2/oauth-best-practice • Added to OAuth to enable migrating applications from HTTP Basic Auth or using a stored password to OAuth 

@aaronpk June 2020 Password • Exposes the username and password to the application • Even for first-party / trusted clients, this increases the attack surface • Trains users that it's okay to enter their password in more than one place • Difficult or impossible to extend to support multifactor or passwordless authentication (WebCrypto, WebAuthn) 

@aaronpk June 2020 OAuth 2.0 Security BCP • All OAuth clients MUST use PKCE with the authorization code flow • Password grant MUST NOT be used • Use exact string matching for redirect URIs • No access tokens in query strings • Refresh tokens for public clients must be 
 sender-constrained or one-time use oauth.net/2/oauth-best-practice 

@aaronpk June 2020 In-Progress Work • JWT Profile for Access Tokens • DPoP (Proof of Possession) 

@aaronpk June 2020 JWT Profile for Access Tokens oauth.net/2/jwt-access-tokens eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJpc3MiO iJodHRwczovL2F1dGhvcml6YXRpb24tc2VydmVyLmV4YW1 wbGUuY29tLyIsInN1YiI6IiA1YmE1NTJkNjciLCJhdWQiO iJodHRwczovL3JzLmV4YW1wbGUuY29tLyIsImV4cCI6MTU 5MzQ4NjY0OCwiY2xpZW50X2lkIjoiczZCaGRSa3F0M18iL CJzY29wZSI6Im9wZW5pZCBwcm9maWxlIHJlYWRlbWFpbCI sImp0aSI6IjAxODEwMmE1LTkzYmQtNDE0OC05ODI2LThlY TE3NTBjMjMyNiIsImlhdCI6MTU5MzQ4MzA0OH0.lWWmEU2 kxTtlwu5TOTkXa7e7ZUNd0WbKtsef7EuJyB8 

@aaronpk June 2020 JWT Profile for Access Tokens oauth.net/2/jwt-access-tokens {"typ":"at+JWT","alg":"RS256","kid":"RjEwOwOA"} { "iss": "https://authorization-server.example.com/", "sub": " 5ba552d67", "aud": "https://rs.example.com/", "exp": 1544645174, "client_id": "s6BhdRkqt3_", "scope": "openid profile reademail" } 

@aaronpk June 2020 DPoP oauth.net/2/dpop POST /token HTTP/1.1 Host: server.example.com Content-Type: application/x-www-form-urlencoded;charset=UTF-8 DPoP: eyJ0eXAiOiJkcG9wK2p3dCIsImFsZyI6IkVTMjU2IiwiandrIjp7Imt0eSI6Ik VDIiwieCI6Imw4dEZyaHgtMzR0VjNoUklDUkRZOXpDa0RscEJoRjQyVVFVZldWQVdCR nMiLCJ5IjoiOVZFNGpmX09rX282NHpiVFRsY3VOSmFqSG10NnY5VERWclUwQ2R2R1JE QSIsImNydiI6IlAtMjU2In19.eyJqdGkiOiItQndDM0VTYzZhY2MybFRjIiwiaHRtIj oiUE9TVCIsImh0dSI6Imh0dHBzOi8vc2VydmVyLmV4YW1wbGUuY29tL3Rva2VuIiwia WF0IjoxNTYyMjYyNjE2fQ.2-GxA6T8lP4vfrg8v-FdWP0A0zdrj8igiMLvqRMUvwnQg 4PtFLbdLXiOSsX0x7NVY-FNyJK70nfbV37xRZT3Lg grant_type=authorization_code &code=SplxlOBeZQQYbYS6WxSbIA &redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb &code_verifier=bEaL42izcC-o-xBk0K2vuJ6U-y1p9r_wW2dFWIWgjz- 

@aaronpk June 2020 New OAuth Extensions • Rich Authorization Requests (RAR) • Pushed Authorization Requests (PAR) • JWT Authorization Requests (JAR) 

@aaronpk June 2020 Rich Authorization Requests (RAR) • OAuth "scope" is limited to fixed lists of scopes • Need a way to authorize fine-grained transactions or resources • and present that to the user in the authorization interface oauth.net/2/rich-authorization-requests 

@aaronpk June 2020 Pay Merchant123 €123.50 
 from your account ending in 8603 

@aaronpk June 2020 Rich Authorization Requests (RAR) oauth.net/2/rich-authorization-requests 

@aaronpk June 2020 Pushed Authorization Requests (PAR) • Currently, the authorization request is sent in the front-channel • Front-channel is susceptible to inspection and modification • PAR initiates the OAuth flow from the back-channel oauth.net/2/pushed-authorization-requests 

@aaronpk June 2020 Pushed Authorization Requests (PAR) GET /authorize?response_type=code &client_id=s6BhdRkqt3&state=af0ifjsldkj &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb HTTP/1.1 Host: as.example.com POST /as/par HTTP/1.1 Host: as.example.com Content-Type: application/x-www-form-urlencoded Authorization: Basic czZCaGRSa3F0Mzo3RmpmcDBaQnIxS3REUmJuZlZkbUl3 response_type=code &client_id=s6BhdRkqt3&state=af0ifjsldkj &redirect_uri=https%3A%2F%2Fclient.example.org%2Fcb Instead of: Push the request to the AS: oauth.net/2/pushed-authorization-requests 

@aaronpk June 2020 Pushed Authorization Requests (PAR) { "request_uri": "urn:example:bwc4JK-ESC0w8acc191e-Y1LTC2", "expires_in": 90 } GET /authorize?request_uri= urn%3Aexample%3Abwc4JK-ESC0w8acc191e-Y1LTC2 HTTP/1.1 AS responds with a URL: User visits that URL, authorization request details are hidden! oauth.net/2/pushed-authorization-requests 

@aaronpk June 2020 JWT Authorization Requests (JAR) • Create a signed JWT with the authorization request details • Prevents front-channel tampering with the request, similar to PAR • Authenticates the request so the AS knows the client really did initiate it tools.ietf.org/html/draft-ietf-oauth-jwsreq 

@aaronpk June 2020 JWT Authorization Requests (JAR) { "iss": "s6BhdRkqt3", "aud": "https://server.example.com", "response_type": "code id_token", "client_id": "s6BhdRkqt3", "redirect_uri": "https://client.example.org/cb", "scope": "openid", "state": "af0ifjsldkj", "nonce": "n-0S6_WzA2Mj", "max_age": 86400 } eyJhbGciOiJSUzI1NiIsImtpZCI6ImsyYmRjIn0.ewogICAgImlzcyI6ICJzNkJoZF JrcXQzIiwKICAgICJhdWQiOiAiaHR0cHM6Ly9zZXJ2ZXIuZXhhbXBsZS5jb20iLAog ICAgInJlc3BvbnNlX3R5cGUiOiAiY29kZSBpZF90b2tlbiIsCiAgICAiY2xpZW50X2 lkIjogInM2QmhkUmtxdDMiLAogICAgInJlZGlyZWN0X3VyaSI6ICJodHRwczovL2Ns aWVudC5leGFtcGxlLm9yZy9jYiIsCiAgICAic2NvcGUiOiAib3BlbmlkIiwKICAgIC JzdGF0ZSI6ICJhZjBpZmpzbGRraiIsCiAgICAibm9uY2UiOiAibi0wUzZfV3pBMk1q IiwKICAgICJtYXhfYWdlIjogODY0MDAKfQ.Nsxa_18VUElVaPjqW_ToI1yrEJ67BgK b5xsuZRVqzGkfKrOIX7BCx0biSxYGmjK9KJPctH1OC0iQJwXu5YVY-vnW0_PLJb1C2 HG-ztVzcnKZC2gE4i0vgQcpkUOCpW3SEYXnyWnKzuKzqSb1wAZALo5f89B_p6QA6j6 JwBSRvdVsDPdulW8lKxGTbH82czCaQ50rLAg3EYLYaCb4ik4I1zGXE4fvim9FIMs8O CMmzwIB5S-ujFfzwFjoyuPEV4hJnoVUmXR_W9typPf846lGwA8h9G9oNTIuX8Ft2jf pnZdFmLg3_wr3Wa5q3a-lfbgF3S9H_8nN3j1i7tLR_5Nz-g tools.ietf.org/html/draft-ietf-oauth-jwsreq 

@aaronpk June 2020 JWT Authorization Requests (JAR) https://server.example.com/authorize?request=eyJhbGciOiJS... Either passed by value in the URL: https://server.example.com/authorize?request_uri=https://example.org/r... ...by reference in the URL: POST https://server.example.com/authorize request=eyJhbGciOiJS... ...or pushed using PAR: tools.ietf.org/html/draft-ietf-oauth-jwsreq 

@aaronpk June 2020 RFC6749 RFC6750 CLIENT TYPE AUTH GRANT TYPE RFC6819 RFC7009 RFC7592 RFC7662 RFC7636 RFC7591 RFC7519 BUILDING YOUR APPLICATION RFC8252 OIDC RFC8414 STATE TLS CSRF UMA 2 FAPI RFC7515 RFC7516 RFC7517 RFC7518 TOKEN POP SECURITY BCP CIBA HTTP SIGNING MUTUAL TLS SPA BCP JARM JAR TOKEN DPOP PAR 

@aaronpk June 2020 The State of OAuth 2.0 RFC6749 OAuth Core Authorization Code Implicit Password Client Credentials RFC6750 Bearer Tokens Tokens in HTTP Header Tokens in POST Form Body Tokens in GET Query String RFC7636 +PKCE RFC8252 PKCE for mobile Browser App BCP PKCE for SPAs PKCE for confidential clients Security BCP 

@aaronpk June 2020 OAuth 2.1 Authorization Code Client Credentials +PKCE Tokens in HTTP Header Tokens in POST Form Body 

OAuth 2.1 oauth.net/2.1 

@aaronpk June 2020 OAuth 2.1 Consolidate the OAuth 2.0 specs,
 adding best practices, 
 removing deprecated features Capture current best practices in OAuth 2.0 under a single name Add references to extensions that didn't exist when OAuth 2.0 was published 

@aaronpk June 2020 OAuth 2.1 No new behavior defined by OAuth 2.1 Non-Goals: Don't include anything experimental, 
 in progress or not widely implemented 

@aaronpk June 2020 OAuth 2.1 RFC6749 - OAuth 2.0 Core RFC6750 - Bearer Token Usage RFC7636 - PKCE Native App & Browser-Based App BCPs Security BCP • MUST support PKCE for all OAuth clients • No password grant • No implicit flow • Exact string matching for redirect URIs • No access tokens in query strings • Refresh tokens must be sender-constrained or one-time use 

@aaronpk June 2020 OAuth 2.1 oauth.net/2.1 tools.ietf.org/html/draft-parecki-oauth-v2-1 

@aaronpk June 2020 oauth.net/3 ? ? ? 

OAuth 3 aka XYZ aka XAuth 

@aaronpk June 2020 OAuth 3 • In development under a new IETF working group (GNAP) • Re-thinking OAuth from the ground up • Not backwards compatible • Consolidate all the various use cases in OAuth into a new framework 

@aaronpk June 2020 GNAP / TxAuth very much in progress! 

Thank you! @aaronpk aaronpk.com oauth.wtf