Subject: [Errata Held for Document Update] RFC7230 (5964)

From: RFC Errata System <[email-masked]>
Date: Wed, 5 Feb 2020 06:39:07 -0800 (PST)

The following errata report has been held for document update 
for RFC7230, "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing". 

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You may review the report below and at:
https://www.rfc-editor.org/errata/eid5964

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Status: Held for Document Update
Type: Technical

Reported by: Rick van Rein <[email-masked]>
Date Reported: 2020-01-23
Held by: Barry Leiba (IESG)

Section: 2.7.1

Original Text
-------------
   The URI generic syntax for authority also includes a deprecated
   userinfo subcomponent ([RFC3986], Section 3.2.1) for including user
   authentication information in the URI.  Some implementations make use
   of the userinfo component for internal configuration of
   authentication information, such as within command invocation
   options, configuration files, or bookmark lists, even though such
   usage might expose a user identifier or password.  A sender MUST NOT
   generate the userinfo subcomponent (and its "@" delimiter) when an
   "http" URI reference is generated within a message as a request
   target or header field value.  Before making use of an "http" URI
   reference received from an untrusted source, a recipient SHOULD parse
   for userinfo and treat its presence as an error; it is likely being
   used to obscure the authority for the sake of phishing attacks.

Corrected Text
--------------
   The URI generic syntax for authority also includes a
   userinfo subcomponent in which the format "user:password" is deprecated
   ([RFC3986], Section 3.2.1).  The user is permitted, but the password
   is not.  Some implementations make use
   of the userinfo component for internal configuration of
   authentication information, such as within command invocation
   options, configuration files, or bookmark lists, even though such
   usage might expose a user identifier or password.  A sender MUST NOT
   generate a colon in a userinfo subcomponent when an
   "http" URI reference is generated within a message as a request
   target or header field value, but it may prefix a user and an "@" delimiter
   before the host name in an "http" URI.  Before making use of an "http" URI
   reference received from an untrusted source, a recipient SHOULD parse
   for userinfo and treat the presence of a colon in it as an error.

Notes
-----
RFC3986 does not forbid or even discourage the "user" in the userinfo subcomponent.  It only says

   Use of the format "user:password" in the userinfo field is
   deprecated.

and continues to describe ":password" handling.

Obscuring the authority for the purposes of phishing is not mitigated by parsing the userinfo; subdomains in DNS offer similar notational flexibility.  Parsing does help against misleading password popups.

The user is part of the authority section of the URI and its purpose is to zoom in on a scope for authoritative resource addressing.  This syntax has in the past been (ab)used for Basic/Digest authentication details, which only works if visitor and visited resource happen to be the same user; it is this (ab)use that is now deprecated.

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Verifier notes:
This is not really an erratum, as the document says exactly what it was intended to say when it was written.  That said, the issue does need to be discussed as the document is updated, and an update is planned... so I'm marking it "Held for Document Update", rather than "Rejected".

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RFC7230 (draft-ietf-httpbis-p1-messaging-26)
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Title               : Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing
Publication Date    : June 2014
Author(s)           : R. Fielding, Ed., J. Reschke, Ed.
Category            : PROPOSED STANDARD
Source              : Hypertext Transfer Protocol Bis APP
Area                : Applications
Stream              : IETF
Verifying Party     : IESG