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Final drafts adopted by the Workgroup through consensus are circulated publicly for the public review for 60 days and for the OIDF members for voting. Publication as an OIDF Standard requires approval by at least 50 % of the members casting a vote. There is a possibility that some of the elements of this document may be the subject to patent rights. OIDF shall not be held responsible for identifying any or all such patent rights.
Financial-grade API Security Profile 1.0 consists of the following parts:
These parts are intended to be used with RFC6749, RFC6750, RFC7636, and OIDC.
The Financial-grade API is a highly secured OAuth profile that aims to provide specific implementation guidelines for security and interoperability. The Financial-grade API security profile can be applied to APIs in any market area that requires a higher level of security than provided by standard OAuth or OpenID Connect. Among other security enhancements, this specification provides a secure alternative to screen scraping. Screen scraping accesses user's data and functions by impresonating a user through password sharing. This brittle, inefficient, and insecure practice creates security vulnerabilities which require financial institutions to allow what appears to be an automated attack against their applications.
This document is Part 1 of FAPI Security Profile 1.0. It specifies a baseline security profile of OAuth that is suitable for protecting APIs with a moderate inherent risk. Importantly, this profile does not provide non-repudiation (signing of authorization requests and responses) and sender-constrained access tokens. If such features or a higher level of security is desired, the use of Financial-grade API Security Profile 1.0 - Part 2: Advanced is recommended.
Although it is possible to code an OpenID Provider and Relying Party from first principles using this specification, the main audience for this specification is parties who already have a certified implementation of OpenID Connect and want to achieve a higher level of security. Implementers are encouraged to understand the security considerations contained in Section 7.6 before embarking on a 'from scratch' implementation.
The key words "shall", "shall not", "should", "should not", "may", and "can" in this document are to be interpreted as described in ISO Directive Part 2. These key words are not used as dictionary terms such that any occurrence of them shall be interpreted as key words and are not to be interpreted with their natural language meanings.
2. Normative references
3. Terms and definitions
4. Symbols and abbreviated terms
5. Baseline security profile
5.2. Baseline security provisions
5.2.2. Authorization server
126.96.36.199. Returning authenticated user's identifier
188.8.131.52. Client requesting openid scope
184.108.40.206. Clients not requesting openid scope
5.2.3. Public client
5.2.4. Confidential client
6. Accessing Protected Resources
6.2. Baseline access provisions
6.2.1. Protected resources provisions
6.2.2. Client provisions
7. Security considerations
7.1. TLS and DNSSEC considerations
7.2. Message source authentication failure
7.3. Message integrity protection failure
7.4. Message containment failure
7.4.1. Authorization request and response
7.4.2. Token request and response
7.4.3. Resource request and response
7.5. Native Apps
7.6. Incomplete or incorrect implementations of the specifications
7.7. Discovery & Multiple Brands
8. Privacy considerations
Appendix A. Copyright notice & license
§ Authors' Addresses
This document specifies the method for an application to:
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applied. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISODIR2 - ISO/IEC Directives Part 2
RFC4122 - A Universally Unique IDentifier (UUID) URN Namespace
RFC6749 - The OAuth 2.0 Authorization Framework
RFC6750 - The OAuth 2.0 Authorization Framework: Bearer Token Usage
RFC7636 - Proof Key for Code Exchange by OAuth Public Clients
RFC6125 - Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS)
BCP212 - OAuth 2.0 for Native Apps
RFC6819 - OAuth 2.0 Threat Model and Security Considerations
BCP195 - Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)
OIDC - OpenID Connect Core 1.0 incorporating errata set 1
X.1254 - Entity authentication assurance framework
MTLS - OAuth 2.0 Mutual TLS Client Authentication and Certificate Bound Access Tokens
RFC8414 - OAuth 2.0 Authorization Server Metadata
OIDD - OpenID Connect Discovery 1.0 incorporating errata set 1
RFC7231 - Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content
For the purpose of this document, the terms defined in RFC6749, RFC6750, RFC7636, OpenID Connect Core apply.
API – Application Programming Interface
CSRF - Cross Site Request Forgery
FAPI - Financial-grade API
HTTP – Hyper Text Transfer Protocol
REST – Representational State Transfer
TLS – Transport Layer Security
The OIDF Financial-grade API (FAPI) security profile specifies security requirements for API resources protected by the OAuth 2.0 Authorization Framework that consists of RFC6749, RFC6750, RFC7636, and other specifications.
FAPI Security Profile 1.0 - Part 1: Baseline and Part 2: Advanced specify different levels of security. The characteristics required of the tokens are different and the methods to obtain tokens are explained separately. This document specifies the baseline security provisions.
Some APIs, such as ones that provide potentially sensitive information, require a greater level of protection than basic RFC6749 requires. FAPI provides such greater protection.
As a profile of the OAuth 2.0 Authorization Framework, this document mandates the following to the baseline profile of the FAPI Security Profile 1.0.
The authorization server
Further, if it is desired to provide the authenticated user's identifier to the client in the token response, the authorization server:
If the client requests the openid scope, the authorization server
If the client does not requests the openid scope, the authorization server
A public client
In addition to the provisions for a public client, a confidential client
The FAPI endpoints are OAuth 2.0 protected resource endpoints that return protected information for the resource owner associated with the submitted access token.
The resource server with the FAPI endpoints
The client supporting this document
As confidential information is being exchanged, all interactions shall be encrypted with TLS (HTTPS).
The recommendations for Secure Use of Transport Layer Security in BCP195 shall be followed, with the following additional requirements:
Endpoints for the use by web browsers should use mechanisms to ensure that connections cannot be downgraded using TLS Stripping attacks. A preloaded HTTP Strict Transport Security policy (see PRELOAD and RFC6797) can be used for this purpose. Some top-level domains, like .bank and .insurance, have set such a policy and therefore protect all second-level domains below them.
For a comprehensive protection against network attackers, all endpoints should additionally use DNSSEC to protect against DNS spoofing attacks that can lead to the issuance of rogue domain-validated TLS certificates.
NOTE: Even if an endpoint uses only organization validated (OV) or extended validation (EV) TLS certificates, rogue domain-validated certificates can be used to impersonate the endpoints and conduct man-in-the-middle attacks. CAA records RFC8659 can help to mitigate this risk.
Authorization request and response are not authenticated. For higher risk scenarios, they should be authenticated. See Financial-grade API Security Profile 1.0 - Part 2: Advanced, which uses request objects to achieve the message source authentication.
The authorization request does not have message integrity protection and hence request tampering and parameter injection are possible. Where such protection is desired, Financial-grade API Security Profile 1.0 - Part 2: Advanced should be used.
The response is integrity protected when the ID Token is returned from the authorization endpoint.
In this document, the authorization request is not encrypted. Thus, it is possible to leak the information contained if the web browser is compromised.
Authorization response can be encrypted as ID Token can be encrypted.
It is possible to leak the information through the logs if the parameters were recorded in the logs and the access to the logs are compromised. Strict access control to the logs in such cases should be enforced.
It is possible to leak information through the logs if the parameters were recorded in the logs and the access to the logs are compromised. Strict access control to the logs in such cases should be enforced.
Care should be taken so that the sensitive data will not be leaked through the referrer.
If the access token is a bearer token, it is possible to exercise the stolen token. Since the access token can be used against multiple URIs, the risk of leaking is much larger than the refresh token, which is used only against the token endpoint. Thus, the lifetime of the access token should be much shorter than that of the refresh token. Refer to Section 16.18 of OIDC for more discussion on the lifetimes of access tokens and refresh tokens.
When native apps are used as either public clients, dynamically registered confidential clients or user-agents receiving the authorization response for a server based confidential client, the recommendations for OAuth 2.0 for Native Apps in BCP212 shall be followed, with the following additional requirements:
When registering redirect URIs, authorization servers
These requirements mean that FAPI Security Profile 1.0 compliant implementations can only support native apps through the use of "Claimed https Scheme URI Redirection".
NOTE: Nothing in this document seeks to disallow fixed urls in the form https://localhost:port-number/callback, as these are particularly useful in non-production systems or in clients used in development, to facilitate faster and easier development.
To achieve the full security benefits, it is important the implementation of this specification, and the underlying OpenID Connect and OAuth specifications, are both complete and correct.
The OpenID Foundation provides tools that can be used to confirm that an implementation is correct:
The OpenID Foundation maintains a list of certified implementations:
Deployments that use this specification should use a certified implementation.
Organizations who need to support multiple "brands" with individual authorization endpoints from a single Authorization Server deployment shall use a separate issuer per brand. This can be achieved either at the domain level (e.g. https://brand-a.auth.example.com and https://brand-b.auth.example.com) or with different paths (e.g. https://auth.example.com/brand-a and https://auth.example.com/brand-b)
As stated in 5.2.2-22 Clients shall only use metadata values obtained via metadata documents as defined in OIDD. Communicating metadata through other means (e.g. via email) opens up a social engineering attack vector.
Note that the requirement to use OIDD is not a requirement to support Dynamic Client Registration.
There are many factors to be considered in terms of privacy when implementing this document. However, since this document is a profile of OAuth and OpenID Connect, all of them are generic and apply to OAuth or OpenID Connect and are not specific to this document. Implementers are advised to perform a thorough privacy impact assessment and manage identified risks appropriately.
NOTE: Implementers can consult documents like ISO29100 and [ISO29134] for this purpose.
Privacy threats to OAuth and OpenID Connect implementations include the following:
These threats can be mitigated by choosing appropriate options in OAuth or OpenID, or by introducing some operational rules. For example, "Attacker observing personal data in authorization request" can be mitigated by either using authorization request by reference using request_uri or by encrypting the request object. Similarly, "Attacker observing personal data in authorization endpoint response" can be mitigated by encrypting the ID Token or JARM response.
The following people contributed to this document:
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