IETF Logo Mail Archive

Re: [ietf-dkim] Mailsploit

Pawel Lesnikowski <lesnikowski@limilabs.com> Tue, 05 December 2017 22:58 UTC

Return-Path: <ietf-dkim-bounces@mipassoc.org>
X-Original-To: ietfarch-ietf-dkim-archive@ietfa.amsl.com
Delivered-To: ietfarch-ietf-dkim-archive@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 4CA7412895E for <ietfarch-ietf-dkim-archive@ietfa.amsl.com>; Tue, 5 Dec 2017 14:58:35 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.288
X-Spam-Level:
X-Spam-Status: No, score=-1.288 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, HEADER_FROM_DIFFERENT_DOMAINS=0.001, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_SORBS_SPAM=0.5, SPF_PASS=-0.001, T_DKIM_INVALID=0.01, URIBL_BLOCKED=0.001] autolearn=no autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=fail (1024-bit key) reason="fail (body has been altered)" header.d=limilabs.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id fU31pU56tAJB for <ietfarch-ietf-dkim-archive@ietfa.amsl.com>; Tue, 5 Dec 2017 14:58:29 -0800 (PST)
Received: from simon.songbird.com (simon.songbird.com [72.52.113.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 8046B128B90 for <ietf-dkim-archive@ietf.org>; Tue, 5 Dec 2017 14:58:29 -0800 (PST)
Received: from simon.songbird.com (simon.songbird.com [127.0.0.1]) by simon.songbird.com (8.14.4/8.14.4/Debian-4.1ubuntu1) with ESMTP id vB5MrNID024434; Tue, 5 Dec 2017 14:53:25 -0800
Authentication-Results: simon.songbird.com; dkim=fail reason="verification failed; unprotected key" header.d=limilabs.com header.i=@limilabs.com header.b=HhZR8Prr; dkim-adsp=none (unprotected policy); dkim-atps=neutral
Received: from mail-qt0-f177.google.com (mail-qt0-f177.google.com [209.85.216.177]) by simon.songbird.com (8.14.4/8.14.4/Debian-4.1ubuntu1) with ESMTP id vB5MrJvk024414 (version=TLSv1/SSLv3 cipher=AES128-GCM-SHA256 bits=128 verify=NOT) for <ietf-dkim@mipassoc.org>; Tue, 5 Dec 2017 14:53:21 -0800
Received: by mail-qt0-f177.google.com with SMTP id r39so4728443qtr.13 for <ietf-dkim@mipassoc.org>; Tue, 05 Dec 2017 14:53:03 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=limilabs.com; s=alpha; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=enodi6MLGRw4QmMMeM3RK4kwomWCT6AcdwUdcEK/6SI=; b=HhZR8Prr0EDs8+P4dbjXdbqVq3AmBocTVdY9bsGBt0gXgdHiKx4KLGJZgZKHSsqEMt uCocJmI6ROreroMsSHXtPfSWC8Wd+90guCU1bMhI+f3SJEOzPgstsP/o4bXvQ8WDkFJm 8Y9QZbxVF6rdWBieSzpXiF2f3Bs3TMcgSYV2k=
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=enodi6MLGRw4QmMMeM3RK4kwomWCT6AcdwUdcEK/6SI=; b=jakyU/vL/boAb4B1r70J6A8rbSlvxJMk7zRvSzLsG2zILwjl9mHLKOGNcnCBDQXKh4 4THffcg4ShNeL46OhAGzl7Ju50svgkMaRvTdwv3nUXfUv/d/ap2S/9E/fnLCCnjCOJnW HSwhMPQfoqKfZD+D2fuUvF2nsPzYoi2soa5UROJOdbMiV8ARcEZNJF3XRPVCOr6BKStW +weOdMxQeCTxogGbkLJHnJ32XIPVQM3/B9m+u4QWMPrpJLhNuB5PIdZALNe9FnPcTLbG OYtaU1R1ZLRjwGU4ReNU50ZM7cC31LzcMs5kIau7HFOCizMad2D/sf5C1Xdghti0Mmw6 +9wg==
X-Gm-Message-State: AKGB3mKCkDcCI0k6JQ8s8Zubbw2FJcnPasZYQPuaZqt2LfUrCiuExw6C eJDzyH1pmYelX4g/pzQ3w4Fmwmwho2i7lCRwqToeuCg=
X-Google-Smtp-Source: AGs4zMa/0RRUh0IiDac9ButhB7fB6sYkjfcd70fOQEy6Zds6FrundFiU2jkZcx263io7KiJPbT/IgrX3oQfHwDE6N70=
X-Received: by 10.200.63.208 with SMTP id v16mr3041143qtk.249.1512514376860; Tue, 05 Dec 2017 14:52:56 -0800 (PST)
MIME-Version: 1.0
Received: by 10.237.41.68 with HTTP; Tue, 5 Dec 2017 14:52:26 -0800 (PST)
X-Originating-IP: [89.73.253.223]
In-Reply-To: <75c9b339-b60f-0b06-e613-ef40a131e280@spamtrap.tnetconsulting.net>
References: <CAHNGrjEzrmdbjhxf_W2qkX8eiSoSaoYoiMDma3yuM2brS6KVmw@mail.gmail.com> <75c9b339-b60f-0b06-e613-ef40a131e280@spamtrap.tnetconsulting.net>
From: Pawel Lesnikowski <lesnikowski@limilabs.com>
Date: Tue, 05 Dec 2017 23:52:26 +0100
Message-ID: <CAHNGrjG60zXS+S9XQQwuBANcKM8WAzXOF=CRZW_nCoZmJULchg@mail.gmail.com>
To: Grant Taylor <gtaylor@tnetconsulting.net>
Cc: ietf-dkim@mipassoc.org
Subject: Re: [ietf-dkim] Mailsploit
X-BeenThere: ietf-dkim@mipassoc.org
X-Mailman-Version: 2.1.16
Precedence: list
List-Id: IETF DKIM Discussion List <ietf-dkim.mipassoc.org>
List-Unsubscribe: <http://mipassoc.org/mailman/options/ietf-dkim>, <mailto:ietf-dkim-request@mipassoc.org?subject=unsubscribe>
List-Archive: <http://mipassoc.org/pipermail/ietf-dkim/>
List-Post: <mailto:ietf-dkim@mipassoc.org>
List-Help: <mailto:ietf-dkim-request@mipassoc.org?subject=help>
List-Subscribe: <http://mipassoc.org/mailman/listinfo/ietf-dkim>, <mailto:ietf-dkim-request@mipassoc.org?subject=subscribe>
Content-Type: multipart/mixed; boundary="===============4288886154397139855=="
Errors-To: ietf-dkim-bounces@mipassoc.org
Sender: ietf-dkim <ietf-dkim-bounces@mipassoc.org>

>
>
>> What is "naive" or "incorrect" about the following decoding?
>
> potus@whitehouse.gov<null>potus@whitehouse.gov@mailsploit.com
>
> "=?utf-8?b?cG90dXNAd2hpdGVob3VzZS5nb3Y=?=" quite literally does decode to
> "potus@whitehouse.gov"
>

encoded-words are simply not permitted inside email addresses. MUA
shouldn't attempt to decode this at all.


>
> Or are you indicating that the naivety is the fact that MUAs may
> incorrectly handle the null containing string?  Possibly believing that the
> MUA will use null termination and incorrectly believe that the From:
> address is just "potus@whitehouse.gov"?
>
>
Attempting to decode is the first problem, incorrectly handling null
terminators and new lines is the second issue.
MUAs simply don't expect new lines and null terminators there.


> Although it's not a direct attack on DKIM, if DKIM is implemented properly
>> and email address decoding and displaying isn't, users might be fooled.
>>
>
> That is an MUA issue.  Perhaps DKIM helps re-enforce an incorrect
> assumption based on a bad MUA trait.  But I don't see that as a DKIM issue.


DKIM works as expected, but as you said it may re-enforce an incorrect
assumption that email is from respected source.

_______________________________________________
NOTE WELL: This list operates according to
http://mipassoc.org/dkim/ietf-list-rules.html

v2.23.0 | Report a Bug | By Email