Internet Engineering Task Force (IETF) S. Hollenbeck Request for Comments: 7481 Verisign Labs Category: Standards Track N. Kong ISSN: 2070-1721 CNNIC March 2015 Security Services for the Registration Data Access Protocol (RDAP)
AbstractThe Registration Data Access Protocol (RDAP) provides "RESTful" web services to retrieve registration metadata from Domain Name and Regional Internet Registries. This document describes information security services, including access control, authentication, authorization, availability, data confidentiality, and data integrity for RDAP. Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7481. Copyright Notice Copyright (c) 2015 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 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions Used in This Document . . . . . . . . . . . . . . 2 2.1. Acronyms and Abbreviations . . . . . . . . . . . . . . . 3 3. Information Security Services and RDAP . . . . . . . . . . . 3 3.1. Access Control . . . . . . . . . . . . . . . . . . . . . 3 3.2. Authentication . . . . . . . . . . . . . . . . . . . . . 3 3.2.1. Federated Authentication . . . . . . . . . . . . . . 4 3.3. Authorization . . . . . . . . . . . . . . . . . . . . . . 6 3.4. Availability . . . . . . . . . . . . . . . . . . . . . . 6 3.5. Data Confidentiality . . . . . . . . . . . . . . . . . . 7 3.6. Data Integrity . . . . . . . . . . . . . . . . . . . . . 7 4. Privacy Threats Associated with Registration Data . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.1. Normative References . . . . . . . . . . . . . . . . . . 10 6.2. Informative References . . . . . . . . . . . . . . . . . 11 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 RFC7482], "JSON Responses for the Registration Data Access Protocol (RDAP)" [RFC7483], and "HTTP Usage in the Registration Data Access Protocol (RDAP)" [RFC7480]. One goal of RDAP is to provide security services that do not exist in the WHOIS [RFC3912] protocol, including access control, authentication, authorization, availability, data confidentiality, and data integrity. This document describes how each of these services is achieved by RDAP using features that are available in other protocol layers. Additional or alternative mechanisms can be added in the future. Where applicable, informative references to requirements for a WHOIS replacement service [RFC3707] are noted. RFC2119].
RFC4949]. No requirements have been identified for other security services. Section 10.2.2 of [RFC7483]) that identifies the access granted to the client.
WHOIS does not provide features to identify and authenticate clients. As noted in Section 184.108.40.206 of "Cross Registry Internet Service Protocol (CRISP) Requirements" [RFC3707], there is utility in allowing server operators to offer "varying degrees of access depending on policy and need." Clients have to be identified and authenticated to provide that utility. RDAP's authentication framework needs to accommodate anonymous access as well as verification of identities using a range of authentication methods and credential services. To that end, RDAP clients and servers MUST implement the authentication framework specified in "Hypertext Transfer Protocol (HTTP/1.1): Authentication" [RFC7235]. The "basic" scheme can be used to send a client's user name and password to a server in plaintext, base64-encoded form. The "digest" scheme can be used to authenticate a client without exposing the client's plaintext password. If the "basic" scheme is used, HTTP over TLS [RFC2818] MUST be used to protect the client's credentials from disclosure while in transit (see Section 3.5). Servers MUST support either Basic or Digest authentication; they are not required to support both. Clients MUST support both to interoperate with servers that support one or the other. Servers may provide a login page that triggers HTTP authentication. Clients should continue sending the HTTP authentication header once they receive an initial 401 (Unauthorized) response from the HTTP server as long as the scheme portion of the URL doesn't change. The Transport Layer Security protocol [RFC5246] includes an optional feature to identify and authenticate clients who possess and present a valid X.509 digital certificate [RFC5280]. Support for this feature is OPTIONAL. RDAP does not impose any unique server authentication requirements. The server authentication provided by TLS fully addresses the needs of RDAP. In general, transports for RDAP must either provide a TLS-protected transport (e.g., HTTPS) or a mechanism that provides an equivalent level of server authentication. Work on HTTP authentication methods continues. RDAP is designed to be agile enough to support additional methods as they are defined.
credential management complexity. RDAP MAY include a federated authentication mechanism that permits a client to access multiple RDAP servers in the same federation with one credential. Federated authentication mechanisms used by RDAP MUST be fully supported by HTTP. OAuth, OpenID, Security Assertion Markup Language (SAML), and mechanisms based on Certification Authority (CA) are all possible approaches to provide federated authentication. At the time of this document's publication, negotiation or advertisement of federated authentication services is still an undefined mechanism by the noted federated authentication protocols. Developing this mechanism is beyond the scope of this document. The OAuth authorization framework [RFC6749] describes a method for users to access protected web resources without having to hand out their credentials. Instead, clients are issued access tokens by authorization servers with the permission of the resource owners. Using OAuth, multiple RDAP servers can form a federation, and the clients can access any server in the same federation by providing one credential registered in any server in that federation. The OAuth authorization framework is designed for use with HTTP and thus can be used with RDAP. OpenID [OpenID] is a decentralized single sign-on authentication system that allows users to log in at multiple web sites with one ID instead of having to create multiple unique accounts. An end user can freely choose which OpenID provider to use and can preserve their Identifier if they switch OpenID providers. Note that OAuth and OpenID do not consistently require data confidentiality services to protect interactions between providers and consumers. HTTP over TLS [RFC2818] can be used as needed to provide protection against man-in-the-middle attacks. SAML 2.0 [SAML] is an XML-based protocol that can be used to implement web-based authentication and authorization services, including single sign on. It uses security tokens containing assertions to exchange information about an end user between an identity provider and a service provider. The Transport Layer Security protocol describes the specification of a client certificate in Section 7.4.6 of [RFC5246]. Clients who possess and present a valid X.509 digital certificate, issued by a CA, could be identified and authenticated by a server who trusts the corresponding CA. A certificate authentication method can be used to achieve federated authentication in which multiple RDAP servers all trust the same CAs, and then any client with a certificate issued by a trusted CA can access any RDAP server in the federation. This
certificate-based mechanism is supported by HTTPS and can be used with RDAP. Section 220.127.116.11 of "Cross Registry Internet Service Protocol (CRISP) Requirements" [RFC3707], there is utility in allowing server operators to offer "varying degrees of access depending on policy and need." Access control decisions can be made once a client's identity has been established and authenticated (see Section 3.2). Server operators MAY offer varying degrees of access depending on policy and need in conjunction with the authentication methods described in Section 3.2. If such varying degrees of access are supported, an RDAP server MUST provide granular access controls (that is, per registration data object) in order to implement authorization policies. Some examples: - Clients will be allowed access only to data for which they have a relationship. - Unauthenticated or anonymous access status may not yield any contact information. - Full access may be granted to a special group of authenticated clients. The type of access allowed by a server will most likely vary from one operator to the next. A description of the response privacy considerations associated with different levels of authorization can be found in Section 13 of [RFC7483]. RFC4732] is advised. An RDAP service MAY use an HTTP throttling mechanism to limit the number of queries that a single client can send in a given period of time. If used, the server SHOULD return an HTTP 429 (Too Many Requests) response code as described in "Additional HTTP Status Codes" [RFC6585]. A client that receives a 429 response SHOULD decrease its query rate and honor the Retry-After header field if one
is present. Note that this is not a defense against denial-of-service attacks, since a malicious client could ignore the code and continue to send queries at a high rate. A server might use another response code if it did not wish to reveal to a client that rate limiting is the reason for the denial of a reply. RFC2818] to provide that protection by encrypting all traffic sent on the connection between client and server. HTTP over TLS MUST be used to protect all client-server exchanges unless operational constraints make it impossible to meet this requirement. It is also possible to encrypt discrete objects (such as command path segments and JSON- encoded response objects) at one endpoint, send them to the other endpoint via an unprotected transport protocol, and decrypt the object on receipt. Encryption algorithms as described in "Internet Security Glossary, Version 2" [RFC4949] are commonly used to provide data confidentiality at the object level. There are no current requirements for object-level data confidentiality using encryption. Support for this feature could be added to RDAP in the future. As noted in Section 3.2, the HTTP "basic" authentication scheme can be used to authenticate a client. When this scheme is used, HTTP over TLS MUST be used to protect the client's credentials from disclosure while in transit. If the policy of the server operator requires encryption to protect client-server data exchanges (such as to protect non-public data that cannot be accessed without client identification and authentication), HTTP over TLS MUST be used to protect those exchanges. A description of privacy threats that can be addressed with confidentiality services can be found in Section 4. Section 10.2.2 of [RFC7483] describes status values that can be used to describe operator actions used to protect response data from disclosure to unauthorized clients. RFC2818] to provide that protection by using a keyed Message Authentication Code (MAC) to detect modifications. It is also possible to sign discrete objects (such as command path segments and JSON-encoded response objects) at one endpoint, send them to the
other endpoint via a transport protocol, and validate the signature of the object on receipt. Digital signature algorithms as described in "Internet Security Glossary, Version 2" [RFC4949] are commonly used to provide data integrity at the object level. There are no current requirements for object-level data integrity using digital signatures. Support for this feature could be added to RDAP in the future. The most specific need for this service is to provide assurance that HTTP 30x redirection hints [RFC7231] and response elements returned from the server are not modified while in transit. If the policy of the server operator requires message integrity for client-server data exchanges, HTTP over TLS MUST be used to protect those exchanges.
according to the sensitivity of the data, the privileges of the clients, or some other heuristics. RDAP uses the jCard [RFC7095] standard format for entity representation. Operators may find that many of the jCard fields are irrelevant for registry operation purposes or that they have no reason to collect information from registrants that would correspond to certain fields. Operators wishing to reduce privacy risks for registrants may restrict which information they collect and/or which fields they populate in responses. In addition to privacy risks to registrants, there are also potential privacy risks for those who query registration data. For example, the fact that a registry employee performs a particular query may reveal information about the employee's activities that he or she would have preferred to keep private. RDAP supports the use of HTTP over TLS to provide privacy protection for those querying registrant data as well as registrants, unless operational constraints make it impossible to meet this requirement. Section 3.2.1, digital certificates can be used to implement federated authentication. There is a risk of too promiscuous, or even rogue, CAs being included in the list of acceptable CAs that the TLS server sends the client as part of the
TLS client-authentication handshake and lending the appearance of trust to certificates signed by those CAs. Periodic monitoring of the list of CAs that RDAP servers trust for client authentication can help reduce this risk. The Transport Layer Security protocol [RFC5246] includes a null cipher suite that does not encrypt data and thus does not provide data confidentiality. This option MUST NOT be used when data confidentiality services are needed. Additional considerations for secure use of TLS are described in [SECURE-TLS-DTLS]. Data integrity services are sometimes mistakenly associated with directory service operational policy requirements focused on data accuracy. "Accuracy" refers to the truthful association of data elements (such as names, addresses, and telephone numbers) in the context of a particular directory object (such as a domain name). Accuracy requirements are out of scope for this protocol. Additional security considerations are described in the specifications for HTTP [RFC7231], HTTP Basic and Digest access authentication [RFC7235], HTTP over TLS [RFC2818], and additional HTTP status codes [RFC6585]. Security considerations for federated authentication systems can be found in the OAuth [RFC6749] and OpenID [OpenID] specifications. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>. [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000, <http://www.rfc-editor.org/info/rfc2818>. [RFC6585] Nottingham, M. and R. Fielding, "Additional HTTP Status Codes", RFC 6585, April 2012, <http://www.rfc-editor.org/info/rfc6585>. [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content", RFC 7231, June 2014, <http://www.rfc-editor.org/info/rfc7231>. [RFC7235] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Authentication", RFC 7235, June 2014, <http://www.rfc-editor.org/info/rfc7235>.
[RFC7480] Newton, A., Ellacott, B., and N. Kong, "HTTP Usage in the Registration Data Access Protocol (RDAP)", RFC 7480, March 2015, <http://www.rfc-editor.org/info/rfc7480>. [RFC7482] Newton, A. and S. Hollenbeck, "Registration Data Access Protocol (RDAP) Query Format", RFC 7482, March 2015, <http://www.rfc-editor.org/info/rfc7482>. [RFC7483] Newton, A. and S. Hollenbeck, "JSON Responses for the Registration Data Access Protocol (RDAP)", RFC 7483, March 2015, <http://www.rfc-editor.org/info/rfc7483>. [OpenID] OpenID Foundation, "OpenID Authentication 2.0 - Final", December 2007, <http://specs.openid.net/auth/2.0>. [RFC3707] Newton, A., "Cross Registry Internet Service Protocol (CRISP) Requirements", RFC 3707, February 2004, <http://www.rfc-editor.org/info/rfc3707>. [RFC3912] Daigle, L., "WHOIS Protocol Specification", RFC 3912, September 2004, <http://www.rfc-editor.org/info/rfc3912>. [RFC4732] Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet Denial-of-Service Considerations", RFC 4732, December 2006, <http://www.rfc-editor.org/info/rfc4732>. [RFC4949] Shirey, R., "Internet Security Glossary, Version 2", FYI 36, RFC 4949, August 2007, <http://www.rfc-editor.org/info/rfc4949>. [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, August 2008, <http://www.rfc-editor.org/info/rfc5246>. [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., Housley, R., and W. Polk, "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile", RFC 5280, May 2008, <http://www.rfc-editor.org/info/rfc5280>. [RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework", RFC 6749, October 2012, <http://www.rfc-editor.org/info/rfc6749>. [RFC7095] Kewisch, P., "jCard: The JSON Format for vCard", RFC 7095, January 2014, <http://www.rfc-editor.org/info/rfc7095>.
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