Extended Security Considerations for the Automatic Certificate Management Environment (ESecACME)
draft-fiebig-acme-esecacme-00

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Last updated 2018-10-21
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ACME Working Group                                             T. Fiebig
Internet-Draft                                                  TU Delft
Intended status: Standards Track                             K. Borgolte
Expires: April 24, 2019                             Princeton University
                                                        October 21, 2018

     Extended Security Considerations for the Automatic Certificate
                   Management Environment (ESecACME)
                     draft-fiebig-acme-esecacme-00

Abstract

   By now, most Public Key Infrastructure X.509 (PKIX) certificates are
   issued via the ACME protocol.  Recently, several attacks against
   domain validation (DV) have been published, including IP-use-after-
   free, (forced) on-path attacks, and attacks on protocols used for
   validation.  In general, these attacks can be mitigated by
   (selectively) requirering additional challenges, e.g., DNS
   validation, proof of prior-key-ownership, or in severe cases even
   extended validation (EV) instead of DV.  This document provides a
   list of critical cases and describes which mitigations can be used to
   reduce the threat of issuing a certificate to an unauthorized party.

Status of This Memo

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   This Internet-Draft will expire on April 24, 2019.

Copyright Notice

   Copyright (c) 2018 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

Fiebig & Borgolte        Expires April 24, 2019                 [Page 1]
Internet-Draft                  ESecACME                    October 2018

   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Attacks . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  IP/Resource-use-after-free  . . . . . . . . . . . . . . .   3
       2.1.1.  Detection . . . . . . . . . . . . . . . . . . . . . .   4
       2.1.2.  Defense . . . . . . . . . . . . . . . . . . . . . . .   4
     2.2.  (Forced)-on-path Attacks  . . . . . . . . . . . . . . . .   4
       2.2.1.  Detection . . . . . . . . . . . . . . . . . . . . . .   5
       2.2.2.  Defense . . . . . . . . . . . . . . . . . . . . . . .   5
     2.3.  DNS Cache Poisoning Attacks . . . . . . . . . . . . . . .   5
       2.3.1.  Detection . . . . . . . . . . . . . . . . . . . . . .   5
       2.3.2.  Defense . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Summary Indicators for Additional Validation  . . . . . . . .   5
     3.1.  High-Resource-Reuse Source / Cloud Provider . . . . . . .   5
     3.2.  Multi-Vantagepoint Validation Mismatch  . . . . . . . . .   5
     3.3.  BGP monitoring  . . . . . . . . . . . . . . . . . . . . .   6
     3.4.  DNS Fragmentation . . . . . . . . . . . . . . . . . . . .   6
     3.5.  Failed DNSSEC Validation  . . . . . . . . . . . . . . . .   6
     3.6.  Recent Domain Transfer  . . . . . . . . . . . . . . . . .   6
     3.7.  High-Risk Domains . . . . . . . . . . . . . . . . . . . .   6
   4.  Additional Validation Options . . . . . . . . . . . . . . . .   6
     4.1.  Proof of Prior Key Ownership  . . . . . . . . . . . . . .   6
       4.1.1.  Limitations . . . . . . . . . . . . . . . . . . . . .   7
     4.2.  Additional Use of a DNS Challenge . . . . . . . . . . . .   7
       4.2.1.  Limitations . . . . . . . . . . . . . . . . . . . . .   7
     4.3.  Additional Use of an Email Challenge  . . . . . . . . . .   7
       4.3.1.  Limitations . . . . . . . . . . . . . . . . . . . . .   7
       4.3.2.  Limitations . . . . . . . . . . . . . . . . . . . . .   7
     4.4.  Out-of-Band and offline validation  . . . . . . . . . . .   7
       4.4.1.  Limitations . . . . . . . . . . . . . . . . . . . . .   8
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
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