Attack and Threat Model for Certificate Transparency
draft-ietf-trans-threat-analysis-12

Document Type Active Internet-Draft (trans WG)
Last updated 2017-10-13
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Public Notary Transparency                                       S. Kent
Internet-Draft                                          BBN Technologies
Intended status: Informational                          October 13, 2017
Expires: April 13, 2017

          Attack and Threat Model for Certificate Transparency
                  draft-ietf-trans-threat-analysis-12

Abstract

   This document describes an attack model and discusses threats for the
   Web PKI context in which security mechanisms to detect mis-issuance
   of web site certificates are being developed.  The model provides an
   analysis of detection and remediation mechanisms for both syntactic
   and semantic mis-issuance.  The model introduces an outline of
   attacks to organize the discussion.  The model also describes the
   roles played by the elements of the Certificate Transparency (CT)
   system, to establish a context for the model.

Status of This Memo

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   This Internet-Draft will expire on April 13, 2018.

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

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Kent                     Expires April 13, 2018                 [Page 1]
Internet-Draft  Attack Model for Certificate Mis-issuance   October 2017

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Conventions used in this document . . . . . . . . . . . .   7
   2.  Threats . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   3.  Semantic mis-issuance . . . . . . . . . . . . . . . . . . . .   9
     3.1.  Non-malicious Web PKI CA context  . . . . . . . . . . . .   9
       3.1.1.  Certificate logged  . . . . . . . . . . . . . . . . .   9
       3.1.2.  Certificate not logged  . . . . . . . . . . . . . . .  11
     3.2.  Malicious Web PKI CA context  . . . . . . . . . . . . . .  12
       3.2.1.  Certificate logged  . . . . . . . . . . . . . . . . .  12
       3.2.2.  Certificate not logged  . . . . . . . . . . . . . . .  14
     3.3.  Undetected Compromise of CAs or Logs  . . . . . . . . . .  15
       3.3.1.  Compromised CA, Benign Log  . . . . . . . . . . . . .  15
       3.3.2.  Benign CA, Compromised Log  . . . . . . . . . . . . .  17
       3.3.3.  Compromised CA, Compromised Log . . . . . . . . . . .  17
     3.4.  Attacks Based on Exploiting Multiple Certificate Chains .  18
     3.5.  Attacks Related to Distribution of Revocation Status  . .  20
   4.  Syntactic mis-issuance  . . . . . . . . . . . . . . . . . . .  21
     4.1.  Non-malicious Web PKI CA context  . . . . . . . . . . . .  21
       4.1.1.  Certificate logged  . . . . . . . . . . . . . . . . .  21
       4.1.2.  Certificate not logged  . . . . . . . . . . . . . . .  23
     4.2.  Malicious Web PKI CA context  . . . . . . . . . . . . . .  23
       4.2.1.  Certificate logged  . . . . . . . . . . . . . . . . .  24
       4.2.2.  Certificate is not logged . . . . . . . . . . . . . .  25
   5.  Issues Applicable to Sections 3 and 4 . . . . . . . . . . . .  25
     5.1.  How does a Subject know which Monitor(s) to use?  . . . .  25
     5.2.  How does a Monitor discover new logs? . . . . . . . . . .  25
     5.3.  CA response to report of a bogus or erroneous certificate  26
     5.4.  Browser behavior  . . . . . . . . . . . . . . . . . . . .  26
     5.5.  Remediation for a malicious CA  . . . . . . . . . . . . .  26
     5.6.  Auditing - detecting misbehaving logs . . . . . . . . . .  27
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  28
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  28
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  29
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