Re: [quicwg/base-drafts] Get rid of DoS vulnerability in Reserved Bits (#2280)

Martin Thomson <notifications@github.com> Mon, 31 December 2018 06:41 UTC

Return-Path: <noreply@github.com>
X-Original-To: quic-issues@ietfa.amsl.com
Delivered-To: quic-issues@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 3A24F12875B for <quic-issues@ietfa.amsl.com>; Sun, 30 Dec 2018 22:41:33 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -8.065
X-Spam-Level:
X-Spam-Status: No, score=-8.065 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.065, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=0.001, MAILING_LIST_MULTI=-1, RCVD_IN_DNSWL_HI=-5, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1024-bit key) header.d=github.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 yWEFKvCFwjGZ for <quic-issues@ietfa.amsl.com>; Sun, 30 Dec 2018 22:41:31 -0800 (PST)
Received: from out-3.smtp.github.com (out-3.smtp.github.com [192.30.252.194]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 1B9A112867A for <quic-issues@ietf.org>; Sun, 30 Dec 2018 22:41:31 -0800 (PST)
Date: Sun, 30 Dec 2018 22:41:29 -0800
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=github.com; s=pf2014; t=1546238489; bh=buN4LzMMbIYiPVzcLxtv2+UeCgFj0I5a4fLE8R6WpQk=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=BLaenyQYnfsewGqUzST/bDW/+qCMpuMQ5n4EkpnJGhXSJPmKH12sMG7dM9l8KvkMg QiQ/lqj97saUsQeokP+O7scxd7A6dxuRcNZ7iZCwTHPoBlCYjVd4XSNtXEXmhyGw5g gijb1qTk8dyydcvFnhpGCM9ea1ovskrz8GJpPyyU=
From: Martin Thomson <notifications@github.com>
Reply-To: quicwg/base-drafts <reply+0166e4abec284480d06a2a937ad10e79cc157ba6ef2d24c592cf0000000118417c1992a169ce178a377a@reply.github.com>
To: quicwg/base-drafts <base-drafts@noreply.github.com>
Cc: Subscribed <subscribed@noreply.github.com>
Message-ID: <quicwg/base-drafts/pull/2280/c450613338@github.com>
In-Reply-To: <quicwg/base-drafts/pull/2280@github.com>
References: <quicwg/base-drafts/pull/2280@github.com>
Subject: Re: [quicwg/base-drafts] Get rid of DoS vulnerability in Reserved Bits (#2280)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5c29ba19b9a9e_774b3fd6cbed45b814752a"; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: list
X-GitHub-Sender: martinthomson
X-GitHub-Recipient: quic-issues
X-GitHub-Reason: subscribed
X-Auto-Response-Suppress: All
X-GitHub-Recipient-Address: quic-issues@ietf.org
Archived-At: <https://mailarchive.ietf.org/arch/msg/quic-issues/vNByi0EPSTR_SVUNEKbU1oSExWQ>
X-BeenThere: quic-issues@ietf.org
X-Mailman-Version: 2.1.29
List-Id: Notification list for GitHub issues related to the QUIC WG <quic-issues.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/quic-issues>, <mailto:quic-issues-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/quic-issues/>
List-Post: <mailto:quic-issues@ietf.org>
List-Help: <mailto:quic-issues-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/quic-issues>, <mailto:quic-issues-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 31 Dec 2018 06:41:33 -0000

This requirement exists because if you only remove header protection then throw the packet away, you create a side channel that allows an attacker some leverage on your header protection keys.  [The TLS draft](https://quicwg.org/base-drafts/draft-ietf-quic-tls.html#rfc.section.9.3) says:

>  For authentication to be free from side-channels, the entire process of header protection removal, packet number recovery, and packet protection removal MUST be applied together without timing and other side-channels.

Yes, it's perverse, but there are lots of cases where extra work is done to avoid creating side channels.  This ain't static RSA and the attack here isn't a Bleichenbacker attack, but there are good reasons.  And if you are suggesting that this sort of timing can't be observed, that's proven not to be the case before (see [NetSpectre](https://misc0110.net/web/files/netspectre.pdf))

As for a DoS vulnerability, there are two bits, so you will be doing the work for 1 in four packets anyway.  And it's not hard to find packets with valid sequences.

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/quicwg/base-drafts/pull/2280#issuecomment-450613338