Attack and Threat Model for Certificate Transparency
draft-ietf-trans-threat-analysis-16

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Public Notary Transparency                                       S. Kent
Internet-Draft                                               Independent
Intended status: Informational                           October 4, 2018
Expires: April 7, 2019

          Attack and Threat Model for Certificate Transparency
                  draft-ietf-trans-threat-analysis-16

Abstract

   This document defines an attack model and discusses threats based on
   the system design presented in [I-D.ietf-trans-rfc6962-bis].  It
   analyzes potential vulnerabilities associated with that design, and
   considers compromises of system elements and malicious behavior by
   such elements.  It does not consider implementation vulnerabilities,
   including ones that might enable denial of service attacks against
   these elements.

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
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

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   and may be updated, replaced, or obsoleted by other documents at any
   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 April 7, 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
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of

Kent                      Expires April 7, 2019                 [Page 1]
Internet-Draft  Attack Model for Certificate Mis-issuance   October 2018

   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Conventions used in this document . . . . . . . . . . . .   9
   2.  Threats . . . . . . . . . . . . . . . . . . . . . . . . . . .   9
   3.  Semantic mis-issuance . . . . . . . . . . . . . . . . . . . .  10
     3.1.  Non-malicious CA context  . . . . . . . . . . . . . . . .  10
       3.1.1.  Certificate logged  . . . . . . . . . . . . . . . . .  11
         3.1.1.1.  Benign log  . . . . . . . . . . . . . . . . . . .  11
         3.1.1.2.  Misbehaving log . . . . . . . . . . . . . . . . .  11
         3.1.1.3.  Misbehaving third party Monitor . . . . . . . . .  13
       3.1.2.  Certificate not logged  . . . . . . . . . . . . . . .  13
     3.2.  Malicious CA context  . . . . . . . . . . . . . . . . . .  13
       3.2.1.  Certificate logged  . . . . . . . . . . . . . . . . .  13
         3.2.1.1.  Benign log  . . . . . . . . . . . . . . . . . . .  13
         3.2.1.2.  Misbehaving log . . . . . . . . . . . . . . . . .  14
         3.2.1.3.  Misbehaving third party Monitor . . . . . . . . .  15
       3.2.2.  Certificate not logged  . . . . . . . . . . . . . . .  15
         3.2.2.1.  CT-aware browser  . . . . . . . . . . . . . . . .  15
     3.3.  Undetected Compromise of CAs or Logs  . . . . . . . . . .  16
       3.3.1.  Compromised CA, Benign Log  . . . . . . . . . . . . .  16
       3.3.2.  Benign CA, Compromised Log  . . . . . . . . . . . . .  18
       3.3.3.  Compromised CA, Compromised Log . . . . . . . . . . .  18
     3.4.  Attacks Based on Exploiting Multiple Certificate Chains .  19
     3.5.  Attacks Related to Distribution of Revocation Status  . .  21
   4.  Syntactic mis-issuance  . . . . . . . . . . . . . . . . . . .  22
     4.1.  Non-malicious CA context  . . . . . . . . . . . . . . . .  22
       4.1.1.  Certificate logged  . . . . . . . . . . . . . . . . .  22
         4.1.1.1.  Benign log  . . . . . . . . . . . . . . . . . . .  23
         4.1.1.2.  Misbehaving log or third party Monitor  . . . . .  24
       4.1.2.  Certificate not logged  . . . . . . . . . . . . . . .  24
         4.1.2.1.  Self-monitoring Subject . . . . . . . . . . . . .  24
       4.1.3.  Situations Independent of Certificate Logging . . . .  25
         4.1.3.1.  Self-monitoring Subject and Benign third party
                   Monitor . . . . . . . . . . . . . . . . . . . . .  25
         4.1.3.2.  CT-enabled browser  . . . . . . . . . . . . . . .  25
     4.2.  Malicious CA context  . . . . . . . . . . . . . . . . . .  25