MUD (D)TLS profiles for IoT devices
draft-reddy-opsawg-mud-tls-00

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OPSWG WG                                                        T. Reddy
Internet-Draft                                                    McAfee
Intended status: Standards Track                                 D. Wing
Expires: February 7, 2020                                         Citrix
                                                          August 6, 2019

                  MUD (D)TLS profiles for IoT devices
                     draft-reddy-opsawg-mud-tls-00

Abstract

   This memo extends Manufacturer Usage Description (MUD) to model DTLS
   and TLS usage.  This allows a network element to notice abnormal DTLS
   or TLS usage which has been strong indicator of other software
   running on the endpoint, typically malware.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on February 7, 2020.

Copyright Notice

   Copyright (c) 2019 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
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   (https://trustee.ietf.org/license-info) in effect on the date of
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Overview of MUD (D)TLS profiles for IoT devices . . . . . . .   4
   4.  (D)TLS profile YANG module  . . . . . . . . . . . . . . . . .   5
     4.1.  Tree Structure  . . . . . . . . . . . . . . . . . . . . .   6
     4.2.  YANG Module . . . . . . . . . . . . . . . . . . . . . . .   7
   5.  (D)TLS 1.3 handshake  . . . . . . . . . . . . . . . . . . . .  11
     5.1.  Encrypted SNI . . . . . . . . . . . . . . . . . . . . . .  11
     5.2.  Full (D)TLS 1.3 handshake inspection  . . . . . . . . . .  12
   6.  MUD File Example  . . . . . . . . . . . . . . . . . . . . . .  13
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  14
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  14
     10.2.  Informative References . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   Encryption is necessary to protect the privacy of end users using IoT
   devices.  In a network setting, TLS [RFC8446] and DTLS
   [I-D.ietf-tls-dtls13] are the dominant protocols to provide
   encryption for IoT device traffic.  Unfortunately in conjunction with
   IoT applications rise of encryption, malware is also using encryption
   which thwarts network-based analysis such as deep packet inspection
   (DPI).  Other mechanisms are needed to notice malware is running on
   the IoT device.

   Malware frequently uses its own libraries for its activities, and
   those libraries are re-used much like any other software engineering
   project.  Research [malware] indicates there are observable
   differences in how malware uses encryption compared with non-malware
   uses encryption.  There are several interesting findings specific to
   DTLS and TLS which were found common to malware:

   o  Older and weaker cryptographic parameters (e.g.,
      TLS_RSA_WITH_RC4_128_SHA).

   o  TLS SNI and server certificates are composed of subjects with
      characteristics of a domain generation algorithm (DGA) (e.g.,
      www.33mhwt2j.net).

   o  Higher use of self-signed certificates compared with typical
      legitimate software.

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   o  Discrepancies in the server name indication (SNI) TLS extension in