Authorized update to MUD URLs
draft-richardson-opsawg-mud-acceptable-urls-00

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OPSAWG Working Group                                       M. Richardson
Internet-Draft                                  Sandelman Software Works
Intended status: Best Current Practice                  January 21, 2020
Expires: July 24, 2020

                     Authorized update to MUD URLs
             draft-richardson-opsawg-mud-acceptable-urls-00

Abstract

   This document provides a way for an RFC8520 Manufacturer Usage
   Description (MUD) definitions to declare what are acceptable
   replacement URLs for a device.

Status of This Memo

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   This Internet-Draft will expire on July 24, 2020.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Updating MUD URLs vs Updating MUD files . . . . . . . . . . .   3
     2.1.  Updating the MUD file in place  . . . . . . . . . . . . .   3
       2.1.1.  Adding capabilities . . . . . . . . . . . . . . . . .   3
       2.1.2.  Removing capabilities . . . . . . . . . . . . . . . .   4
       2.1.3.  Significant changes to protocols  . . . . . . . . . .   4
     2.2.  Motivation for updating MUD URLs  . . . . . . . . . . . .   5
   3.  Threat model for MUD URLs . . . . . . . . . . . . . . . . . .   5
     3.1.  leveraging the manufacturer signature . . . . . . . . . .   5
     3.2.  Concerns about same-signer mechanism  . . . . . . . . . .   5
   4.  Proposed possible Extension . . . . . . . . . . . . . . . . .   5
     4.1.  Semantic changes only . . . . . . . . . . . . . . . . . .   6
     4.2.  Add an extension  . . . . . . . . . . . . . . . . . . . .   6
   5.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Appendix A.  Appendices . . . . . . . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   [RFC8520] provides a standardized way to describe how a specific
   purpose device makes use of Internet resources.  Access Control Lists
   (ACLs) can be defined in an RFC8520 Manufacturer Usage Description
   (MUD) file that permit a device to access Internet resources by DNS
   name.

   MUD URLs can come from a number of sources:

   o  IDevID Extensions

   o  DHCP

   o  LLDP

   o  [I-D.richardson-opsawg-securehomegateway-mud] proposes to scan
      them from QRcodes.

   The IDevID mechanism provides a URL that is asserted
   cryptographically by a manufacturer.  However, it is difficult for
   manufacturers to update the IDevID of a device which is already in a
   box.

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   The DHCP and LLDP mechanisms are not signed, but are asserted by the
   device.  A firmware update may update what MUD URL is emitted.
   Sufficiently well targetted malware could also change the MUD URL.

   The QRcode mechanism is usually done via paper/stickers, and is
   typically not under the control of the device itself at all.

   While MUD files may include signatures, it is not mandatory to check
   them, and there is not a clear way to connect the entity which signed
   the MUD file to the device itself.  A malicious device does not need