Internet DRAFT - draft-hanson-oauth-cookie-response-mode
draft-hanson-oauth-cookie-response-mode
Network Working Group J. Hanson
Internet-Draft Okta
Intended status: Standards Track 16 February 2024
Expires: 19 August 2024
OAuth Cookie Response Mode
draft-hanson-oauth-cookie-response-mode-00
Abstract
This specification defines a response mode for OAuth 2.0 that uses a
cookie to obtain and transmit an access token. In this mode, the
access token is encoded using an HTTP Set-Cookie header and
transmitted via the HTTP Cookie header to the client or resource
server.
About This Document
This note is to be removed before publishing as an RFC.
The latest revision of this draft can be found at
https://aaronpk.github.io/draft-hanson-oauth-cookie-response-mode/
draft-hanson-oauth-cookie-response-mode.html. Status information for
this document may be found at https://datatracker.ietf.org/doc/draft-
hanson-oauth-cookie-response-mode/.
Source for this draft and an issue tracker can be found at
https://github.com/aaronpk/draft-hanson-oauth-cookie-response-mode.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 19 August 2024.
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Copyright Notice
Copyright (c) 2024 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
3. User-Agent-based Applications . . . . . . . . . . . . . . . . 3
4. Cookie Response Mode . . . . . . . . . . . . . . . . . . . . 4
4.1. Authorization Request . . . . . . . . . . . . . . . . . . 4
4.2. Access Token Response . . . . . . . . . . . . . . . . . . 5
5. Accessing Protected Resources . . . . . . . . . . . . . . . . 5
5.1. Bearer Token Usage . . . . . . . . . . . . . . . . . . . 5
5.1.1. Cookie Request Header Field . . . . . . . . . . . . . 5
5.2. Unauthenticated Requests . . . . . . . . . . . . . . . . 6
6. TODO . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . 8
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
OAuth was initially created to allow third-party clients to access
protected resources hosted by a resource server, with the approval of
the resource owner. It has proven useful in first-party scenarios as
well, where clients and resource servers are managed by the same
organization.
The implicit grant defined by OAuth is a flow optimized for clients
implemented in a browser using a scripting language such as
JavaScript. In this flow, the client is issued the access token
directly, where, due to the nature of browsers, it may be exposed to
other applications with access to the resource owner's user-agent.
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Due to this, OAuth does not support issuance of refresh tokens via
the implicit grant, as refresh tokens are typically long-lasting
credentials that must be kept confidential and not exposed to
unauthorized parties.
With the increasing adoption of OAuth, new threat models and security
best current practices have been identified in
[I-D.ietf-oauth-security-topics] and
[I-D.ietf-oauth-browser-based-apps]. These new practices recommend
the use of authorization code grant by browser-based applications and
advise against use of the implicit grant.
The rationale for the shift in guidance is sound, as the implicit
grant is susceptible to a number of a attack vectors that aren't
applicable to the authorization code grant. However, concerns around
exposing tokens to unauthorized parties with access to the user-agent
remain, and may be exacerbated if refresh tokens are introduced to an
environment in which they were previously forbidden.
These concerns are unavoidable, especially in scenarios where
delegation is granted to third-party clients. However, first-party
scenarios have the ability to use cookies, which can be limited in
such a way that they aren't exposed to JavaScript. Such limits
mitigate various attack vectors, benefiting scenarios in which use of
cookies is applicable.
This specification defines a response mode for OAuth 2.0 that uses a
cookie to transmit an access token. In this mode, the access token
is encoded using an HTTP Set-Cookie header and transmitted via the
the HTTP Cookie header to the client or resource server.
2. Conventions and Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. User-Agent-based Applications
This specification applies to user-agent-based applications, which is
a client profile defined in Section 2.1 of [RFC6749]. A user-agent-
based application is a public client in which the client code is
downloaded from a web server and executes within a user-agent (e.g.,
web browser) on the device used by the resource owner. Protocol data
and credentials are easily accessible (and often visible) to the
resource owner. Since such applications reside within the user-
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agent, they can make seamless use of the user-agent capabilities when
requesting authorization.
This specification has been designed around the following user-agent-
based application profiles, representing common architectual patterns
for building web applications:
"multi-page application": A multi-page application (MPA) is a user-
agent-based application that interacts with the user using
hypertext, where each interaction triggers a request to a server
which responds with a new page that is loaded into the browser. A
MPA makes use of HTML links, forms, and HTTP redirects.
"single-page application": A single-page application (SPA) is a
user- agent-based application that interacts with the user by
dynamically rewriting the current page rather than loading entire
new pages from a server. A SPA makes use of JavaScript and web
browser APIs.
"hybrid application": A hybrid application is a user-agent-based
application that interacts with the user using both hypertext and
dynamic scripting. A hybrid application makes use of both HTML
and/or JavaScript within a single page and the entirety of the
application may span multiple pages.
4. Cookie Response Mode
This specification defines the Cookie Response Mode, which is
described with its response_mode parameter value:
"cookie": In this mode, the access token parameter of an
authorization response is encoded in a Set-Cookie HTTP header when
responding to the client.
4.1. Authorization Request
The client constructs the request URI as defined in Section 4.2.1 of
[RFC6749], and includes the response_mode extension parameter as
defined by this specification.
The client directs the resource owner to the constructed URI using an
HTTP redirection response, or by other means available to it via the
user-agent.
For example, the client directs the user-agent to make the following
HTTP request using TLS (with extra line breaks for display purposes
only):
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GET /authorize?response_type=token&client_id=s6BhdRkqt3&state=xyz
&redirect_uri=https%3A%2F%2Fclient%2Eexample%2Ecom%2Fcb
&response_mode=cookie HTTP/1.1
Host: server.example.com
4.2. Access Token Response
If the resource owner grants the access request, the authorization
server issues an access token and delivers it to the client by
including an HTTP Set-Cookie header in the redirection response to
the client as defined by [RFC6265]. Any additional parameters other
than the access token are added to the fragment component of the
redirection URI as defined in Section 4.2.2 of [RFC6749].
For example, the authorization server redirects the user-agent by
sending the following HTTP response (with extra line breaks for
display purposes only):
HTTP/1.1 302 Found
Location: http://example.com/cb#state=xyz&token_type=example
&expires_in=3600
Set-Cookie: at=2YotnFZFEjr1zCsicMWpAA; Path=/
5. Accessing Protected Resources
This specification describes how to use the HTTP state management
mechanism defined by [RFC6265] to access protected resources.
5.1. Bearer Token Usage
[RFC6750] defines how to use bearer tokens in HTTP requests,
primarily using the WWW-Authenticate and Authorization HTTP headers
defined by [RFC7235].
Many user-agent-based applications, particularly multi-page
applications, do not make use of the HTTP Authentication framework to
authorize access to protected resources. Instead, these applications
use cookies to establish a "session" for subsequent requests to the
server. This section defines a method of sending bearer access
tokens in resource requests to resource servers that makes use of the
HTTP state management mechanism implemented by the user-agent within
which a user-agent-based application is executing.
5.1.1. Cookie Request Header Field
When sending the access token using the HTTP state management
mechanism, the client uses the "Cookie" request header field to
transmit the access token.
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For example:
GET /resource HTTP/1.1
Host: server.example.com
Cookie: at=2YotnFZFEjr1zCsicMWpAA
Accept: text/html
This method is implemented by user-agents in such a way that the
"Cookie" request header field, and associated access token, are are
automatically presented by the client to the resource server,
typically without any involvement from the client developer.
For example, a multi-page application would make the above request
when the end-user clicks on a link:
<a href="https://server.example.com/resource">Resource</a>
The corresponding HTTP POST request to the same endpoint would be
made when the end-user submits a form, for example:
<form action="https://server.example.com/resource" method="post">
<label for="description">Name:</label>
<input type="text" id="description" name="description">
<button type="submit">Update</button>
</form>
5.2. Unauthenticated Requests
If the protected resource request does not include authentication
credentials or does not contain an access token that enables access
to the protected resource, the resource server MAY include the HTTP
WWW-Authenticate response header field.
If the resource server includes the HTTP WWW-Authenticate response
header field, it SHOULD use the auth-scheme value Cookie as defined
by [I-D.broyer-http-cookie-auth].
For example:
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HTTP/1.1 401 Unauthorized
WWW-Authenticate: Cookie realm="example"
form-action="/login"
cookie-name=at
Content-Type: text/html
<title>Unauthorized</title>
<form action="/login" method="post">
<label for="username">Username:</label>
<input type="text" id="username" name="username">
<label for="password">Password:</label>
<input type="password" id="password" name="password">
<button type="submit">Sign in</button>
</form>
6. TODO
Discuss cookie attributes like Expires and Path in relation to
Resource servers and token expiration times.
Works when authorization server and the resource server (and the
client?) are the same entity. - Client may need to be same entity as
AS, depending on browser cookie restrictinos like ITP.
7. Security Considerations
TODO Security
8. IANA Considerations
This document has no IANA actions.
9. References
9.1. Normative References
[I-D.broyer-http-cookie-auth]
Broyer, T., "Cookie-based HTTP Authentication", Work in
Progress, Internet-Draft, draft-broyer-http-cookie-auth-
00, 4 January 2009,
<https://datatracker.ietf.org/doc/html/draft-broyer-http-
cookie-auth-00>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
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[RFC6265] Barth, A., "HTTP State Management Mechanism", RFC 6265,
DOI 10.17487/RFC6265, April 2011,
<https://www.rfc-editor.org/rfc/rfc6265>.
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/rfc/rfc6749>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
9.2. Informative References
[I-D.ietf-oauth-browser-based-apps]
Parecki, A., Waite, D., and P. De Ryck, "OAuth 2.0 for
Browser-Based Apps", Work in Progress, Internet-Draft,
draft-ietf-oauth-browser-based-apps-15, 23 October 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-oauth-
browser-based-apps-15>.
[I-D.ietf-oauth-security-topics]
Lodderstedt, T., Bradley, J., Labunets, A., and D. Fett,
"OAuth 2.0 Security Best Current Practice", Work in
Progress, Internet-Draft, draft-ietf-oauth-security-
topics-25, 8 February 2024,
<https://datatracker.ietf.org/doc/html/draft-ietf-oauth-
security-topics-25>.
[RFC6750] Jones, M. and D. Hardt, "The OAuth 2.0 Authorization
Framework: Bearer Token Usage", RFC 6750,
DOI 10.17487/RFC6750, October 2012,
<https://www.rfc-editor.org/rfc/rfc6750>.
[RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Authentication", RFC 7235,
DOI 10.17487/RFC7235, June 2014,
<https://www.rfc-editor.org/rfc/rfc7235>.
Acknowledgments
TODO acknowledge.
Author's Address
Jared Hanson
Okta
Email: jared.hanson@okta.com
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