IETF Logo Mail Archive

[Bimi] Re: Possible security flaw in BIMI spec / interaction of BIMI-supporting MUA with non-BIMI-supporting MTA

Dave Crocker <dhc@dcrocker.net> Mon, 06 May 2024 15:46 UTC

Return-Path: <dhc@dcrocker.net>
X-Original-To: bimi@ietfa.amsl.com
Delivered-To: bimi@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 2E851C14F616 for <bimi@ietfa.amsl.com>; Mon, 6 May 2024 08:46:15 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -7.095
X-Spam-Level:
X-Spam-Status: No, score=-7.095 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_ZEN_BLOCKED_OPENDNS=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_DBL_BLOCKED_OPENDNS=0.001, URIBL_ZEN_BLOCKED_OPENDNS=0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=dcrocker.net
Received: from mail.ietf.org ([50.223.129.194]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id E3PDbuqw0G0f for <bimi@ietfa.amsl.com>; Mon, 6 May 2024 08:46:10 -0700 (PDT)
Received: from sienna.cherry.relay.mailchannels.net (sienna.cherry.relay.mailchannels.net [23.83.223.165]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 763C5C14F693 for <bimi@ietf.org>; Mon, 6 May 2024 08:46:10 -0700 (PDT)
X-Sender-Id: hostingeremail|x-authuser|dhc@dcrocker.net
Received: from relay.mailchannels.net (localhost [127.0.0.1]) by relay.mailchannels.net (Postfix) with ESMTP id 8B2B5141915 for <bimi@ietf.org>; Mon, 6 May 2024 15:46:09 +0000 (UTC)
Received: from uk-fast-smtpout5.hostinger.io (unknown [127.0.0.6]) (Authenticated sender: hostingeremail) by relay.mailchannels.net (Postfix) with ESMTPA id AC801141D2D for <bimi@ietf.org>; Mon, 6 May 2024 15:46:07 +0000 (UTC)
ARC-Seal: i=1; s=arc-2022; d=mailchannels.net; t=1715010368; a=rsa-sha256; cv=none; b=tZnnD4L3WLtvE4kTGN5Qeei5KJ3G6tamTxyUiDItMM8UccFKA9umMuLWB2kdrf2NtnqYlw YxeWCpSLkUp7JzeI3jRCOqZfJ1Zldn3G4nRI9njGI9NTzo1BlB8UgwCAWAWeEX3nYdcGhW uzJc7Y6ZcDKM2InJjivVxFBtMvhB5vNumd0NrzDAr/lbc5dpZcVP87JFUfT1mHoUt7U2R5 p3o2Kh4A1GePoJA8ppflLwXqw5pie0qNU9pQFh3Ftwxt83WuwUtHSwrc9n/jKNlQ8s9Gq6 Ext9vOIS/zf88xB06l3dSBja6O0KgLTYYZ3m3scOS/RxeHPbz/J8LkQ4BP27zw==
ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=mailchannels.net; s=arc-2022; t=1715010368; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Us7XDVNQ4xac/ERM07LhgArU+jcme7UMohM/8w5D2KY=; b=foIRK+Jm4KLhFg3qe9DXw2D9FzfkjX31lLhZYbXc86Gnde6MiL4MjSZwp1099y81pxqWNb HjsZYYkZVKixe/GJq/3E/2ASwnVVyz4KtgMSqZ99uJVedp1mS+JQOQEnKGxllRXtrlRx3z cCNmSvMuSlzVCeNUEihkDXtiPKrmGoC3YA8JZRNmin2CgEWIVglhUtBJQkNdYnN2/5NWAL Rd5EZeQEyE3QY65NF3eq/WkGTqiE2RlWzeGRhQBdbDUDnJRFNhOLnYMsanzOAEjNioDMDD 60GIZ08XkU4zAso/WSOeiTXq7kcNArTwM/rVKT5Dmp2j8XNROYOKrY7Ufs6mMg==
ARC-Authentication-Results: i=1; rspamd-68bbddc7f5-hnht5; auth=pass smtp.auth=hostingeremail smtp.mailfrom=dhc@dcrocker.net
X-Sender-Id: hostingeremail|x-authuser|dhc@dcrocker.net
X-MC-Relay: Neutral
X-MailChannels-SenderId: hostingeremail|x-authuser|dhc@dcrocker.net
X-MailChannels-Auth-Id: hostingeremail
X-Abaft-Blushing: 38e2cbdc1205d6d2_1715010369350_3711381653
X-MC-Loop-Signature: 1715010369350:1477485894
X-MC-Ingress-Time: 1715010369350
Received: from uk-fast-smtpout5.hostinger.io ([UNAVAILABLE]. [31.220.23.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384) by 100.102.9.163 (trex/6.9.2); Mon, 06 May 2024 15:46:09 +0000
Message-ID: <ed09648a-18dc-41f5-98be-2cf6ee88d49a@dcrocker.net>
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dcrocker.net; s=hostingermail-a; t=1715010365; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Us7XDVNQ4xac/ERM07LhgArU+jcme7UMohM/8w5D2KY=; b=BTeTrOHQ/zk2b1BRklCLCeL/hlZpgcFOEP3nwMLihdczrFG8p/5QCS753quJ/oKd+rjADI DWkgkl8oszwWnxAYaEJIG174vKPOXZdubkWkb6RpLZOvtfB6LwDk6luj/7GtkMpQHJA/2M DZKKBAXOJqSyWhE8qa6QYyeuK+T4zOEGTQu8Sa4+rskhntbOopo4WhKfKoJwUM7K/hqwOe cx/3RAdwBY6Djzm1tNGin86OX3QvED3cn0U77cK+x2Y5KJEE23ScCOM+QDkrWDTe+2C5U4 UKl6Cn82hvHRHZGGWv2UGBWZ4WU65wjE49F8EYMZKf8G08UbuEJ5BG9ChYr0FQ==
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Content-Language: en-US
To: bimi@ietf.org
References: <20240505132144.1b62ff64@computer> <f47170e3-66b2-4ccf-8dd7-179d84696d86@zone.ee>
From: Dave Crocker <dhc@dcrocker.net>
Organization: Brandenburg InternetWorking
In-Reply-To: <f47170e3-66b2-4ccf-8dd7-179d84696d86@zone.ee>
Content-Type: text/plain; charset="UTF-8"; format="flowed"
Content-Transfer-Encoding: 8bit
X-CM-Analysis: v=2.4 cv=drzdCUg4 c=1 sm=1 tr=0 ts=6638fb3d a=f0NN86htvrvSmWFZ/FiWJw==:117 a=f0NN86htvrvSmWFZ/FiWJw==:17 a=IkcTkHD0fZMA:10 a=k7Ga1wGzAAAA:8 a=VeclKQMrbXw8IgQ9cbIA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=ijMaxGghyylP-n2pFjDB:22
X-CM-Envelope: MS4xfMSbmIlVqjQPBjNqTgYkdEaTJliIe45FK3/vbpEnwgGBzMa/U/8XFjuW5CtjKIDrDUjPk4a/JF+Xckd93E34o2xxLUwbGJkjSJNQgDiaePeW/MrEl6/E dL66oMNpNIlWfP3biPJMlTGVXcsoCaGwEFy3N+kOt86lIG7NZMKACQfpeiAqUJf1EzBCH9gEnOdoxQ==
X-AuthUser: dhc@dcrocker.net
Message-ID-Hash: 7DY2AWXPGLDUXWGLMFRZJ3SSHQO6Z3G7
X-Message-ID-Hash: 7DY2AWXPGLDUXWGLMFRZJ3SSHQO6Z3G7
X-MailFrom: dhc@dcrocker.net
X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header
X-Mailman-Version: 3.3.9rc4
Precedence: list
Reply-To: dcrocker@bbiw.net
Subject: [Bimi] Re: Possible security flaw in BIMI spec / interaction of BIMI-supporting MUA with non-BIMI-supporting MTA
List-Id: Brand Indicators for Message Identification <bimi.ietf.org>
Archived-At: <https://mailarchive.ietf.org/arch/msg/bimi/5Q7r5cPYOmCH4hKM3mLqMbOQ0WI>
List-Archive: <https://mailarchive.ietf.org/arch/browse/bimi>
List-Help: <mailto:bimi-request@ietf.org?subject=help>
List-Owner: <mailto:bimi-owner@ietf.org>
List-Post: <mailto:bimi@ietf.org>
List-Subscribe: <mailto:bimi-join@ietf.org>
List-Unsubscribe: <mailto:bimi-leave@ietf.org>
Date: Tue, 21 May 2024 17:26:31 -0000
X-Original-Date: Mon, 6 May 2024 08:46:03 -0700

> AFAIK No MUAs actually implement it using those two headers, feel to 
> list any. Current implementations seem to use Authentication-Results 
> (or equivalent) but usable implementations seem to be limited to a 
> specific pairings of MTA+MUA. 


This is a bit confusing.

BIMI is distinctive in that it requires support all the way to the MUA, 
which is where display of the mark will happen.  So the MUA has to be 
part of the trust model.  It must have a means of determining that the 
mark is valid.

If there are multiple ways for this to happen, then either there is no 
standard, or the standard is dramatically more complex and the 
likelihood of operational errors from the complexity as dramatically higher.

Another possibility is that this service is intended only for a very 
restrictedoperational environment.  If so, it needs to be specified 
explicitly, carefully, and completely.

d/

-- 
Dave Crocker
Brandenburg InternetWorking
bbiw.net
mast:@dcrocker@mastodon.social

v2.46.0 | Report a Bug | By Email | System Status