MISP taxonomy format
draft-dulaunoy-misp-taxonomy-format-03

Versions: 00 01 02 03                                                   
Network Working Group                                        A. Dulaunoy
Internet-Draft                                                 A. Iklody
Intended status: Informational                                     CIRCL
Expires: March 8, 2018                                 September 4, 2017


                          MISP taxonomy format
                 draft-dulaunoy-misp-taxonomy-format-03

Abstract

   This document describes the MISP taxonomy format which describes a
   simple JSON format to represent machine tags (also called triple
   tags) vocabularies.  A public directory of common vocabularies MISP
   taxonomies is available and relies on the MISP taxonomy format.  MISP
   taxonomies are used to classify cyber security events, threats or
   indicators.

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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   This Internet-Draft will expire on March 8, 2018.

Copyright Notice

   Copyright (c) 2017 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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   publication of this document.  Please review these documents
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   include Simplified BSD License text as described in Section 4.e of




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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions and Terminology . . . . . . . . . . . . . . .   3
   2.  Format  . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.2.  predicates  . . . . . . . . . . . . . . . . . . . . . . .   4
     2.3.  values  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.4.  optional fields . . . . . . . . . . . . . . . . . . . . .   4
       2.4.1.  colour  . . . . . . . . . . . . . . . . . . . . . . .   4
       2.4.2.  description . . . . . . . . . . . . . . . . . . . . .   5
       2.4.3.  numerical_value . . . . . . . . . . . . . . . . . . .   5
   3.  Directory . . . . . . . . . . . . . . . . . . . . . . . . . .   6
     3.1.  Sample Manifest . . . . . . . . . . . . . . . . . . . . .   7
   4.  Sample Taxonomy in MISP taxonomy format . . . . . . . . . . .   7
     4.1.  Admiralty Scale Taxonomy  . . . . . . . . . . . . . . . .   7
     4.2.  Open Source Intelligence - Classification . . . . . . . .   9
   5.  JSON Schema . . . . . . . . . . . . . . . . . . . . . . . . .  11
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  14
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  14
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .  14
     7.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   Sharing threat information became a fundamental requirements on the
   Internet, security and intelligence community at large.  Threat
   information can include indicators of compromise, malicious file
   indicators, financial fraud indicators or even detailed information
   about a threat actor.  While sharing such indicators or information,
   classification plays an important role to ensure adequate
   distribution, understanding, validation or action of the shared
   information.  MISP taxonomies is a public repository of known
   vocabularies that can be used in threat information sharing.

   Machine tags were introduced in 2007 [machine-tags] to allow users to
   be more precise when tagging their pictures with geolocation.  So a
   machine tag is a tag which uses a special syntax to provide more
   information to users and machines.  Machine tags are also known as
   triple tags due to their format.

   In the MISP taxonomy context, machine tags help analysts to classify
   their cybersecurity events, indicators or threats.  MISP taxonomies
   can be used for classification, filtering, triggering actions or



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   visualisation depending on their use in threat intelligence platforms
   such as MISP [MISP-P].

1.1.  Conventions and Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

2.  Format

   A machine tag is composed of a namespace (MUST), a predicate (MUST)
   and an optional value (OPTIONAL).

   Machine tags are represented as a string.  Below listed are a set of
   sample machine tags for different namespaces such as tlp, admiralty-
   scale and osint.

                tlp:amber
                admiralty-scale:information-credibility="1"
                osint:source-type="blog-post"

   The MISP taxonomy format describes how to define a machine tag
   namespace in a parseable format.  The objective is to provide a
   simple format to describe machine tag (aka triple tag) vocabularies.

2.1.  Overview

   The MISP taxonomy format uses the JSON [RFC4627] format.  Each
   namespace is represented as a JSON object with meta information
   including the following fields: namespace, description, version,
   type.

   namespace defines the overall namespace of the machine tag.  The
   namespace is represented as a string and MUST be present.  The
   description is represented as a string and MUST be present.  A
   version is represented as a decimal and MUST be present.  A type
   defines where a specific taxonomy is applicable and a type can be
   applicable at event, user or org level.  The type is represented as
   an array containing one or more type and SHOULD be present.  If a
   type is not mentioned, by default, the taxonomy is applicable at
   event level only.

   predicates defines all the predicates available in the namespace
   defined. predicates is represented as an array of JSON objects.
   predicates MUST be present and MUST at least content one element.





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   values defines all the values for each predicate in the namespace
   defined. values SHOULD be present.

2.2.  predicates

   The predicates array contains one or more JSON objects which lists
   all the possible predicates.  The JSON object contains two fields:
   value and expanded. value MUST be present. expanded SHOULD be
   present. value is represented as a string and describes the predicate
   value.  The predicate value MUST not contain spaces or colons.
   expanded is represented as a string and describes the human-readable
   version of the predicate value.

2.3.  values

   The values array contain one or more JSON objects which lists all the
   possible values of a predicate.  The JSON object contains two fields:
   predicate and entry. predicate is represented as a string and
   describes the predicate value. entry is an array with one or more
   JSON objects.  The JSON object contains two fields: value and
   expanded. value MUST be present. expanded SHOULD be present. value is
   represented as a string and describes the machine parsable value.
   expanded is represented as a string and describes the human-readable
   version of the value.

2.4.  optional fields

2.4.1.  colour

   colour fields MAY be used at predicates or values level to set a
   specify colour that MAY be used by the implementation.  The colour
   field is described as an RGB colour fill in hexadecimal
   representation.

   Example use of the colour field in the Traffic Light Protocol (TLP):
















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    "predicates": [
        {
          "colour": "#CC0033",
          "expanded": "(TLP:RED) Information exclusively and directly
                       given to (a group of) individual recipients.
                       Sharing outside is not legitimate.",
          "value": "red"
        },
        {
          "colour": "#FFC000",
          "expanded": "(TLP:AMBER) Information exclusively given
                       to an organization; sharing limited within
                       the organization to be effectively acted upon.",
          "value": "amber"
        }...]

2.4.2.  description

   description fields MAY be used at predicates or values level to add a
   descriptive and human-readable information about the specific
   predicate or value.  The field is represented as a string.
   Implementations MAY use the description field to improve more
   contextual information.  The description at the namespace level is a
   MUST as described above.

2.4.3.  numerical_value

   numerical_value fields MAY be used at a predicate or value level to
   add a machine-readable numeric value to a specific predicate or
   value.  The field is represented as a JSON number.  Implementations
   SHOULD use the decimal value provided to support scoring or
   filtering.

   Example use of the numerical_value in the MISP confidence level:

















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              {
               "predicate": "confidence-level",
               "entry": [
                  {
                    "expanded": "Completely confident",
                    "value": "completely-confident",
                    "numerical_value": 100
                  },
                  {
                    "expanded": "Usually confident",
                    "value": "usually-confident",
                    "numerical_value": 75
                  },
                  {
                    "expanded": "Fairly confident",
                    "value": "fairly-confident",
                    "numerical_value": 50
                  },
                  {
                    "expanded": "Rarely confident",
                    "value": "rarely-confident",
                    "numerical_value": 25
                  },
                  {
                    "expanded": "Unconfident",
                    "value": "unconfident",
                    "numerical_value": 0
                  },
                  {
                    "expanded": "Confidence cannot be evaluated",
                    "value": "confidence-cannot-be-evalued"
                  }
               ]
               }

3.  Directory

   The MISP taxonomies directory is publicly available [MISP-T] in a git
   repository.  The repository contains a directory per namespace then a
   file machinetag.json which contains the taxonomy as described in the
   format above.  In the root of the repository, a MANIFEST.json exists
   containing a list of all the taxonomies.

   The MANIFEST.json file is composed of an JSON object with metadata
   like version, license, description, url and path.  A taxonomies array
   describes the taxonomy available with the description, name and
   version field.




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3.1.  Sample Manifest

 {
   "version": "20161009",
   "license": "CC-0",
   "description": "Manifest file of MISP taxonomies available.",
   "url":
     "https://raw.githubusercontent.com/MISP/misp-taxonomies/master/",
   "path": "machinetag.json",
   "taxonomies": [
     {
       "description": "The Admiralty Scale (also called the NATO System)
                       is used to rank the reliability of a source and
                       the credibility of an information.",
       "name": "admiralty-scale",
       "version": 1
     },
     {
       "description": "Open Source Intelligence - Classification.",
       "name": "osint",
       "version": 2
     }]
 }

4.  Sample Taxonomy in MISP taxonomy format

4.1.  Admiralty Scale Taxonomy

      "namespace": "admiralty-scale",
      "description": "The Admiralty Scale (also called the NATO System)
                      is used to rank the reliability of a source and
                      the credibility of an information.",
      "version": 1,
      "predicates": [
        {
          "value": "source-reliability",
          "expanded": "Source Reliability"
        },
        {
          "value": "information-credibility",
          "expanded": "Information Credibility"
        }
      ],
      "values": [
        {
          "predicate": "source-reliability",
          "entry": [
            {



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              "value": "a",
              "expanded": "Completely reliable"
            },
            {
              "value": "b",
              "expanded": "Usually reliable"
            },
            {
              "value": "c",
              "expanded": "Fairly reliable"
            },
            {
              "value": "d",
              "expanded": "Not usually reliable"
            },
            {
              "value": "e",
              "expanded": "Unreliable"
            },
            {
              "value": "f",
              "expanded": "Reliability cannot be judged"
            }
          ]
        },
        {
          "predicate": "information-credibility",
          "entry": [
            {
              "value": "1",
              "expanded": "Confirmed by other sources"
            },
            {
              "value": "2",
              "expanded": "Probably true"
            },
            {
              "value": "3",
              "expanded": "Possibly true"
            },
            {
              "value": "4",
              "expanded": "Doubtful"
            },
            {
              "value": "5",
              "expanded": "Improbable"
            },



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            {
              "value": "6",
              "expanded": "Truth cannot be judged"
            }
          ]
        }
      ]
    }

4.2.  Open Source Intelligence - Classification

 {
   "values": [
     {
       "entry": [
         {
           "expanded": "Blog post",
           "value": "blog-post"
         },
         {
           "expanded": "Technical or analysis report",
           "value": "technical-report"
         },
         {
           "expanded": "News report",
           "value": "news-report"
         },
         {
           "expanded": "Pastie-like website",
           "value": "pastie-website"
         },
         {
           "expanded": "Electronic forum",
           "value": "electronic-forum"
         },
         {
           "expanded": "Mailing-list",
           "value": "mailing-list"
         },
         {
           "expanded": "Block or Filter List",
           "value": "block-or-filter-list"
         },
         {
           "expanded": "Expansion",
           "value": "expansion"
         }
       ],



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       "predicate": "source-type"
     },
     {
       "predicate": "lifetime",
       "entry": [
         {
           "value": "perpetual",
           "expanded": "Perpetual",
           "description": "Information available publicly on long-term"
         },
         {
           "value": "ephemeral",
           "expanded": "Ephemeral",
           "description": "Information available publicly on short-term"
         }
       ]
     },
     {
       "predicate": "certainty",
       "entry": [
         {
           "numerical_value": 100,
           "value": "100",
           "expanded": "100% Certainty",
           "description": "100% Certainty"
         },
         {
           "numerical_value": 93,
           "value": "93",
           "expanded": "93% Almost certain",
           "description": "93% Almost certain"
         },
         {
           "numerical_value": 75,
           "value": "75",
           "expanded": "75% Probable",
           "description": "75% Probable"
         },
         {
           "numerical_value": 50,
           "value": "50",
           "expanded": "50% Chances about even",
           "description": "50% Chances about even"
         },
         {
           "numerical_value": 30,
           "value": "30",
           "expanded": "30% Probably not",



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           "description": "30% Probably not"
         },
         {
           "numerical_value": 7,
           "value": "7",
           "expanded": "7% Almost certainly not",
           "description": "7% Almost certainly not"
         },
         {
           "numerical_value": 0,
           "value": "0",
           "expanded": "0% Impossibility",
           "description": "0% Impossibility"
         }
       ]
     }
   ],
   "namespace": "osint",
   "description": "Open Source Intelligence - Classification",
   "version": 3,
   "predicates": [
     {
       "value": "source-type",
       "expanded": "Source Type"
     },
     {
       "value": "lifetime",
       "expanded": "Lifetime of the information
                    as Open Source Intelligence"
     },
     {
       "value": "certainty",
       "expanded": "Certainty of the elements mentioned
                    in this Open Source Intelligence"
     }
   ]
 }


5.  JSON Schema

   The JSON Schema [JSON-SCHEMA] below defines the structure of the MISP
   taxonomy document as literally described before.  The JSON Schema is
   used validating a MISP taxonomy.  The validation is a _MUST_ if the
   taxonomy is included in the MISP taxonomies directory.

    {
      "$schema": "http://json-schema.org/schema#",



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      "title": "Validator for misp-taxonomies",
      "id": "https://www.github.com/MISP/misp-taxonomies/schema.json",
      "defs": {
        "entry": {
          "type": "array",
          "uniqueItems": true,
          "items": {
            "type": "object",
            "additionalProperties": false,
            "properties": {
              "numerical_value": {
                "type": "number"
              },
              "expanded": {
                "type": "string"
              },
              "description": {
                "type": "string"
              },
              "colour": {
                "type": "string"
              },
              "value": {
                "type": "string"
              },
              "required": [
                "value"
              ]
            }
          }
        },
        "values": {
          "type": "array",
          "uniqueItems": true,
          "items": {
            "type": "object",
            "additionalProperties": false,
            "properties": {
              "entry": {
                "$ref": "#/defs/entry"
              },
              "predicate": {
                "type": "string"
              }
            },
            "required": [
              "predicate"
            ]



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          }
        },
        "predicates": {
          "type": "array",
          "uniqueItems": true,
          "items": {
            "type": "object",
            "additionalProperties": false,
            "properties": {
              "numerical_value": {
                "type": "number"
              },
              "colour": {
                "type": "string"
              },
              "description": {
                "type": "string"
              },
              "expanded": {
                "type": "string"
              },
              "value": {
                "type": "string"
              },
              "required": [
                "value"
              ]
            }
          }
        }
      },
      "type": "object",
      "additionalProperties": false,
      "properties": {
        "version": {
          "type": "integer"
        },
        "description": {
          "type": "string"
        },
        "expanded": {
          "type": "string"
        },
        "namespace": {
          "type": "string"
        },
        "type": {
          "type": "array",



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          "uniqueItems": true,
          "items": {
            "type": "string",
            "enum": [
              "org",
              "user",
              "attribute",
              "event"
            ]
          }
        },
        "refs": {
          "type": "array",
          "uniqueItems": true,
          "items": {
            "type": "string"
          }
        },
        "predicates": {
          "$ref": "#/defs/predicates"
        },
        "values": {
          "$ref": "#/defs/values"
        }
      },
      "required": [
        "namespace",
        "description",
        "version",
        "predicates"
      ]
    }

6.  Acknowledgements

   The authors wish to thank all the MISP community to support the
   creation of open standards in threat intelligence sharing.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
              editor.org/info/rfc2119>.





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   [RFC4627]  Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", RFC 4627,
              DOI 10.17487/RFC4627, July 2006, <https://www.rfc-
              editor.org/info/rfc4627>.

7.2.  Informative References

   [JSON-SCHEMA]
              "JSON Schema: A Media Type for Describing JSON Documents",
              2016, <https://tools.ietf.org/html/draft-wright-json-
              schema>.

   [machine-tags]
              "Machine tags", 2007,
              <https://www.flickr.com/groups/51035612836@N01/
              discuss/72157594497877875/>.

   [MISP-P]   MISP, "MISP Project - Malware Information Sharing Platform
              and Threat Sharing", <https://github.com/MISP>.

   [MISP-T]   MISP, "MISP Taxonomies - shared and common vocabularies of
              tags", <https://github.com/MISP/misp-taxonomies>.

Authors' Addresses

   Alexandre Dulaunoy
   Computer Incident Response Center Luxembourg
   16, bd d'Avranches
   Luxembourg  L-1611
   Luxembourg

   Phone: +352 247 88444
   Email: alexandre.dulaunoy@circl.lu


   Andras Iklody
   Computer Incident Response Center Luxembourg
   16, bd d'Avranches
   Luxembourg  L-1611
   Luxembourg

   Phone: +352 247 88444
   Email: andras.iklody@circl.lu








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