The "hxxp" and "hxxps" URI Schemes
draft-salgado-hxxp-01

Abstract

This document describes the "hxxp" and "hxxps" URI schemes, which are widely used by the security community to obfuscate an http or https URI to avoid being accidentaly interpreted and loaded by a web browser or user-agent.

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This Internet-Draft will expire on November 10, 2017.

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Table of Contents

• 1. Introduction
• 1.1. Requirements Language
• 2. URI Scheme Specification
• 2.1. URI Scheme Syntax
• 2.2. URI Scheme Semantics
• 2.3. Encoding Considerations
• 3. Acknowledgements
• 4. IANA Considerations
• 4.1. URI Scheme Registration
• 5. Security Considerations
• 6. References
• 6.1. Normative References
• 6.2. Informative References
• Author's Address

1. Introduction

This document describes the "hxxp" and "hxxps" URI schemes, which are widely used by the security community to obfuscate an http or https URI to avoid being accidentaly interpreted and loaded by a web browser or user-agent.

These schemes are used in case the resource is dangerous and there is security risks on being automatically processed by an application, such a pre-loading mechanism in web user agents. It also prevents the creation of "clickables" areas in user interfaces, which could detect http or https URIs automatically.

The purpose of this registration is to document its use, prevent any registration of this scheme in the future, explicitly recommend to web application developers to never act with this URI schemes in any way, and provide a safe method for the security community to share malicious information. These schemes must not be treated as an http or https schemes, and must not be identified as web resources. Its consumption is only for humans and documentation, and should be handled with caution by security professionals.

1.1. Requirements Language

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].

2. URI Scheme Specification

2.1. URI Scheme Syntax

The "hxxp" URI syntactically conforms to the <hxxp-uri> rule below, expressed using the Augmented Backus-Naur Form (ABNF) [RFC5234]:

     hxxp-uri = "hxxp:" hxxp-token [ hxxp-query ] [ hxxp-fragment ]
     hxxp-token = *pchar
     hxxp-query = "?" query
     hxxp-fragment = "#" fragment
     pchar     = <as specified in RFC 3986, Appendix A>
     query     = <as specified in RFC 3986, Appendix A>
     fragment  = <as specified in RFC 3986, Appendix A>

            

The "hxxps" URI syntactically conforms to the <hxxps-uri> rule below, expressed using the Augmented Backus-Naur Form (ABNF) [RFC5234]:

     hxxps-uri = "hxxps:" hxxps-token [ hxxps-query ] [ hxxps-fragment ]
     hxxps-token = *pchar
     hxxps-query = "?" query
     hxxps-fragment = "#" fragment
     pchar     = <as specified in RFC 3986, Appendix A>
     query     = <as specified in RFC 3986, Appendix A>
     fragment  = <as specified in RFC 3986, Appendix A>

            

2.2. URI Scheme Semantics

The resource that is referenced by a particular "hxxp" or "hxxps" URI is NOT meant to be interpreted or parsed in any way for applications, or any automated means. The resource MUST be interpreted and consumed by human security professionals.

2.3. Encoding Considerations

"hxxp" and "hxxps" URIs are subject to encoding rules as defined in RFC 3986 [RFC3986].

3. Acknowledgements

The author acknowledges the suggestions and comments made by Fernando Gont and Harlan Lieberman-Berg, for the first revision.

4. IANA Considerations

4.1. URI Scheme Registration

The IANA is requested to register "hxxp" and "hxxps" URI schemes in the "Provisional URI Schemes" registry. The information below is provided according to the guidelines from RFC 7595 [RFC7595]:

-----

Scheme name: hxxp

Status: Provisional

Applications/protocols that use this scheme name: "hxxp" URIs are forbidden to be used by applications.

Contact: Hugo Salgado <hsalgado@nic.cl>

Change controller: Hugo Salgado <hsalgado@nic.cl>

References: "The "hxxp" and "hxxps" URI Schemes" Internet Draft, https://datatracker.ietf.org/doc/draft-salgado-hxxp/

-----

-----

Scheme name: hxxps

Status: Provisional

Applications/protocols that use this scheme name: "hxxps" URIs are forbidden to be used by applications.

Contact: Hugo Salgado <hsalgado@nic.cl>

Change controller: Hugo Salgado <hsalgado@nic.cl>

References: "The "hxxp" and "hxxps" URI Schemes" Internet Draft, https://datatracker.ietf.org/doc/draft-salgado-hxxp/

-----

5. Security Considerations

As stated in the Introduction, the "hxxp" and "hxxps" schemes are forbidden to be used or interpreted by applications. These schemes must be consumed only by humans.

Application developers are encouraged to forbid "hxxp" and "hxxps" schemes URIs inside HTML anchors or tags.

6. References

6.1. Normative References

6.2. Informative References

Author's Address