Re: [quicwg/base-drafts] Add initial threat model to security considerations (#2925)

Martin Thomson <notifications@github.com> Tue, 21 January 2020 06:05 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 14120120071 for <quic-issues@ietfa.amsl.com>; Mon, 20 Jan 2020 22:05:41 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -8
X-Spam-Level:
X-Spam-Status: No, score=-8 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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_HELO_NONE=0.001, 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 WOZOBrKjYdvz for <quic-issues@ietfa.amsl.com>; Mon, 20 Jan 2020 22:05:35 -0800 (PST)
Received: from out-5.smtp.github.com (out-5.smtp.github.com [192.30.252.196]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 02A5D12006E for <quic-issues@ietf.org>; Mon, 20 Jan 2020 22:05:35 -0800 (PST)
Received: from github-lowworker-292e294.va3-iad.github.net (github-lowworker-292e294.va3-iad.github.net [10.48.102.70]) by smtp.github.com (Postfix) with ESMTP id 39923960240 for <quic-issues@ietf.org>; Mon, 20 Jan 2020 22:05:34 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=github.com; s=pf2014; t=1579586734; bh=fNBCSdWDWyPkHJ89hqodIHU+PRBlaAmbchURgqHc5ko=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=SVNyR8lbDB2G+5/YWUT59syLS1hC19zJJt/BZfZFyCnH6z/F4X6gH+bH2mv0Gx18v fyMdDIb+2ZHV0vyriA55YgyFC9vTWKxfp6OZvQadhElq0aG2Ajr8q5S8F3GfTj2DDx RgdDhWBGD/xQ8E8rpa2B/T/T6mKqZLuxAOy4GppM=
Date: Mon, 20 Jan 2020 22:05:34 -0800
From: Martin Thomson <notifications@github.com>
Reply-To: quicwg/base-drafts <reply+AFTOJK73NNGED5ZATWCEX4F4GPDS5EVBNHHBYGSUE4@reply.github.com>
To: quicwg/base-drafts <base-drafts@noreply.github.com>
Cc: Subscribed <subscribed@noreply.github.com>
Message-ID: <quicwg/base-drafts/pull/2925/review/345645852@github.com>
In-Reply-To: <quicwg/base-drafts/pull/2925@github.com>
References: <quicwg/base-drafts/pull/2925@github.com>
Subject: Re: [quicwg/base-drafts] Add initial threat model to security considerations (#2925)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5e2694ae2a331_71e23fba928cd96c127883"; 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/0FInBAvcK_QrgEELyY4v4gKusT4>
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: Tue, 21 Jan 2020 06:05:41 -0000

martinthomson approved this pull request.

Reviewing the amended stuff.  All goodness, though I have a suggestion or two.

I think that @janaiyengar promised to take another look at this, but for me I'm getting tired of staring at this.  I want to merge this very soon.

> +
+#### Server-Side DoS
+
+Computing the server's first flight for a full handshake is potentially
+expensive, requiring both a signature and a key exchange computation.  In order
+to prevent computational DoS attacks, QUIC incorporates a cheap token exchange
+mechanism which allows servers to validate a client's IP address prior to doing
+any expensive computations at the cost of a single round trip.  After a
+successful handshake, servers can issue new tokens to a client which will allow
+new connection establishment without incurring this cost.
+
+#### On-Path Handshake Termination
+
+An on-path attacker can force the QUIC handshake to fail by replacing either the
+client or server Initial messages with invalid messages.  An off-path attacker
+can also mount this attack by racing the Initials.  Once valid Initial messages

As I said elsewhere, this could be simplied to:

> An on-path or off-path attacker can force the QUIC handshake to fail by replacing or racing Initial packets.  Once valid Initial packets [...]

Note: "packet" and not "message".

> +
+Attackers are additionally categorized as either on-path attackers or off-path
+attackers; see Section 3.5 of {{?RFC3552}}.  An on-path attacker can read,
+modify, or remove any packet it observes such that it no longer reaches its
+destination, while an off-path attacker observes the packets, but cannot prevent
+the original packet from reaching its intended destination.  An off-path
+attacker can also transmit arbitrary packets.
+
+Properties of the handshake, protected packets, and connection migration are
+considered separately.
+
+
+### Handshake {#handshake-properties}
+
+The QUIC handshake incorporates the TLS 1.3 handshake and enjoys the
+cryptographic properties described in {{?RFC8446}}; Appendix E.1.

```suggestion
cryptographic properties described in {{?TLS13=RFC8446}}; Appendix E.1.
```

> +
+### Handshake {#handshake-properties}
+
+The QUIC handshake incorporates the TLS 1.3 handshake and enjoys the
+cryptographic properties described in {{?RFC8446}}; Appendix E.1.
+
+In addition to those properties, the QUIC handshake is intended to provide some
+defense against DoS attacks on the handshake, as described below.
+
+#### Anti-Amplification
+
+Because the QUIC handshake can occur without a transport-level round-trip, the
+QUIC server's first flight may be sent to a client whose address it cannot
+validate.  This flight may be long and therefore potentially allows the server
+to be used as a DoS reflector/amplifier.  The mechanisms described in
+{{validate-handshake}} restrict the amplification to a factor of three.

Maybe instead:

> Address validation ({{address-validation}}) is used to verify that an entity that claims a given address is able to receive packets at that address.  Address validation limits amplification attack targets to addresses for which an attacker is either on-path or off-path.
>
> Prior to validation, endpoints are limited in what they are able to send.  During the handshake, a server cannot send more than three times the data it receives; clients that initiate new connections or migrate to a new network path are limited to [um, I can't find a concrete limit in the document].

> +protection ensures that valid packets are only generated by endpoints which
+possess the key material established during the handshake; see {{handshake}} and
+{{handshake-properties}}.  Similarly, any active attacker that observes QUIC
+packets and attempts to insert new data or modify existing data in those packets
+should not be able to generate packets deemed valid by the receiving endpoint.
+
+A spoofing attack, in which an active attacker rewrites unprotected parts of a
+QUIC packet that it forwards or injects, such as the source or destination
+address, is only effective if the attacker can forward packets to the original
+endpoint.  Packet protection ensures that the packet payloads can only be
+processed by the endpoints that completed the handshake, and invalid QUIC
+packets are ignored by those endpoints.
+
+An attacker can also modify the boundaries between QUIC packets and UDP
+datagrams, causing multiple packets to be coalesced into a single datagram, or
+splitting coalesced packets into multiple datagrams.  Such modification has no

```suggestion
splitting coalesced packets into multiple datagrams.  Aside from datagrams containing Initial packets, which require padding, modification has no
```

-- 
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/2925#pullrequestreview-345645852