Unknown Key-Share Attacks on DNS-based Authentications of Named Entities (DANE)
draft-barnes-dane-uks-00

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Last updated 2016-10-09
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Network Working Group                                          R. Barnes
Internet-Draft                                                M. Thomson
Updates: 6698, 7250, 7671 (if approved)                      E. Rescorla
Intended status: Informational                                   Mozilla
Expires: April 12, 2017                                  October 9, 2016

Unknown Key-Share Attacks on DNS-based Authentications of Named Entities
                                 (DANE)
                        draft-barnes-dane-uks-00

Abstract

   Unknown key-share attacks are a class of attacks that allow an
   attacker to deceive one peer of a secure communication as to the
   identity of the remote peer.  When used with traditional, PKI-based
   authentication, TLS-based applications are generally safe from
   unknown key-share attacks.  DNS-based Authentication of Named
   Entities (DANE), however, proposes that applications perform a
   different set of checks as part of authenticating a TLS connection.
   As a result, DANE as currently specified is likely to lead to unknown
   key-share attacks when clients support DANE for authentication.  We
   describe these risks and some simple mitigations.

Status of This Memo

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   This Internet-Draft will expire on April 12, 2017.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents

Barnes, et al.           Expires April 12, 2017                 [Page 1]
Internet-Draft                  DANE UKS                    October 2016

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Attack Synopsis . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Attack Example  . . . . . . . . . . . . . . . . . . . . .   3
   3.  Mitigations . . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   TLS is very widely used to secure application protocols, and in
   particular to authenticate the use of domain names for TLS servers.
   Traditionally, TLS has authenticated a server's use of a domain name
   by having the server present a certificate containing that name, then
   having the client verify that the certificate attests to the name of
   the server to which it was trying to connect (in addition to
   verifying that the certificate is issued by a trusted authority)
   [RFC5280] [RFC6125].

   DNS-based Authentication of Named Entities (DANE) makes modifications
   to this process in order to accommodate the use of DNSSEC-signed
   assertions acquired outside of TLS instead of certificates provided
   in TLS [RFC6698].  This change, together with some recommended
   changes to TLS usage and operational practices, make it possible for
   an attacker to mount unknown key-share attacks against a TLS client
   that supports DANE.

   In this document, we describe how unknown key-share attacks arise
   when a client supports DANE in the manner recommended by the DANE
   specifications, and we propose some changes to DANE that remove these
   risks.

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