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MISP core format
draft-dulaunoy-misp-core-format-00

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This is an older version of an Internet-Draft whose latest revision state is "Active".
Authors Alexandre Dulaunoy , Andras Iklody
Last updated 2016-10-15
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draft-dulaunoy-misp-core-format-00
Network Working Group                                        A. Dulaunoy
Internet-Draft                                                 A. Iklody
Intended status: Informational                                     CIRCL
Expires: April 18, 2017                                 October 15, 2016

                            MISP core format
                   draft-dulaunoy-misp-core-format-00

Abstract

   This document describes the MISP core format used to exchange
   indicators and threat information between MISP (Malware Information
   and threat Sharing Platform) instances.  The JSON format includes the
   overall structure along with the semantic associated for each
   respective key.  The format is described to support other
   implementations which reuse the format and ensuring an
   interoperability with existing MISP [MISP-P] software and other
   Threat Intelligence Platforms.

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   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 18, 2017.

Copyright Notice

   Copyright (c) 2016 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
   (http://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

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   include Simplified BSD License text as described in Section 4.e of
   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.  Event . . . . . . . . . . . . . . . . . . . . . . . . . .   3
       2.2.1.  Event Attributes  . . . . . . . . . . . . . . . . . .   3
     2.3.  Objects . . . . . . . . . . . . . . . . . . . . . . . . .   7
       2.3.1.  Org . . . . . . . . . . . . . . . . . . . . . . . . .   7
       2.3.2.  Orgc  . . . . . . . . . . . . . . . . . . . . . . . .   7
     2.4.  Attribute . . . . . . . . . . . . . . . . . . . . . . . .   8
       2.4.1.  Sample Attribute Object . . . . . . . . . . . . . . .   8
       2.4.2.  Attribute Attributes  . . . . . . . . . . . . . . . .   8
     2.5.  ShadowAttribute . . . . . . . . . . . . . . . . . . . . .  13
       2.5.1.  Sample Attribute Object . . . . . . . . . . . . . . .  13
       2.5.2.  ShadowAttribute Attributes  . . . . . . . . . . . . .  14
       2.5.3.  Org . . . . . . . . . . . . . . . . . . . . . . . . .  18
     2.6.  Tag . . . . . . . . . . . . . . . . . . . . . . . . . . .  19
       2.6.1.  Sample Tag  . . . . . . . . . . . . . . . . . . . . .  19
   3.  Manifest  . . . . . . . . . . . . . . . . . . . . . . . . . .  19
     3.1.  Format  . . . . . . . . . . . . . . . . . . . . . . . . .  20
       3.1.1.  Sample Manifest . . . . . . . . . . . . . . . . . . .  21
   4.  Implementation  . . . . . . . . . . . . . . . . . . . . . . .  23
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  23
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  23
   7.  Sample MISP file  . . . . . . . . . . . . . . . . . . . . . .  23
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  23
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  23
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  24
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  24

1.  Introduction

   Sharing threat information became a fundamental requirements in 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.  MISP [MISP-P] started as an open source
   project in late 2011 and the MISP format started to be widely used as
   an exchange format within the community in the past years.  The aim
   of this document is to describe the specification and the MISP core
   format.

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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

2.1.  Overview

   The MISP core format is in the JSON [RFC4627] format.  In MISP, an
   event is composed of a single JSON object.

   A capitalized key (like Event, Org) represent a data model and a non-
   capitalized key is just an attribute.  This nomenclature can support
   an implementation to represent the MISP format in another data
   structure.

2.2.  Event

   An event is a simple meta structure scheme where attributes and meta-
   data are embedded to compose a coherent set of indicators.  An event
   can be composed from an incident, a security analysis report or a
   specific threat actor analysis.  The meaning of an event only depends
   of the information embedded in the event.

2.2.1.  Event Attributes

2.2.1.1.  uuid

   uuid represents the Universally Unique IDentifier (UUID) [RFC4122] of
   the event.  The uuid MUST be preserved for any updates or transfer of
   the same event.  UUID version 4 is RECOMMENDED when assigning it to a
   new event.

   uuid is represented as a JSON string. uuid MUST be present.

2.2.1.2.  id

   id represents the human-readable identifier associated to the event
   for a specific MISP instance.

   id is represented as a JSON string. id SHALL be present.

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2.2.1.3.  published

   published represents the event publication state.  If the event was
   published, the published value MUST be true.  In any other
   publication state, the published value MUST be false.

   published is represented as a JSON boolean. published MUST be
   present.

2.2.1.4.  info

   info represents the information field of the event. info a free-text
   value to provide a human-readable summary of the event. info SHOULD
   NOT be bigger than 256 characters and SHOULD NOT include new-lines.

   info is represented as a JSON string. info MUST be present.

2.2.1.5.  threat_level_id

   threat_level_id represents the threat level.

   0:
      Undefined

   1:
      Low

   2:
      Medium

   3:
      High

   If a higher granularity is required, a MISP taxonomy applied as a Tag
   SHOULD be preferred.

   threat_level_id is represented as a JSON string. threat_level_id
   SHALL be present.

2.2.1.6.  analysis

   analysis represents the analysis level.

   0:
      Initial

   1:
      Ongoing

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   2:
      Complete

   If a higher granularity is required, a MISP taxonomy applied as a Tag
   SHOULD be preferred.

   analysis is represented as a JSON string. analysis SHALL be present.

2.2.1.7.  date

   date represents a reference date to the event in ISO 8601 format
   (date only: YYYY-MM-DD).  This date corresponds to the date the event
   occured, which may be in the past.

   date is represented as a JSON string. date MUST be present.

2.2.1.8.  timestamp

   timestamp represents a reference time when the event, or one of the
   attributes within the event was created, or last updated/edited on
   the instance. timestamp is expressed in seconds (decimal) since 1st
   of January 1970 (Unix timestamp).  The time zone MUST be UTC.

   timestamp is represented as a JSON string. timestamp MUST be present.

2.2.1.9.  publish_timestamp

   publish_timestamp represents a reference time when the event was
   published on the instance. published_timestamp is expressed in
   seconds (decimal) since 1st of January 1970 (Unix timestamp).  At
   each publication of an event, publish_timestamp MUST be updated.  The
   time zone MUST be UTC.

   publish_timestamp is represented as a JSON string. publish_timestamp
   MUST be present.

2.2.1.10.  org_id

   org_id represents a human-readable identifier referencing an Org
   object of the organization which generated the event.

   The org_id MUST be updated when the event is generated by a new
   instance.

   org_id is represented as a JSON string. org_id MUST be present.

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2.2.1.11.  orgc_id

   orgc_id represents a human-readable identifier referencing an Orgc
   object of the organization which created the event.

   The orgc_id and Orc object MUST be preserved for any updates or
   transfer of the same event.

   orgc_id is represented as a JSON string. orgc_id MUST be present.

2.2.1.12.  attribute_count

   attribute_count represents the number of attributes in the event.
   attribute_count is expressed in decimal.

   attribute_count is represented as a JSON string. attribute_count
   SHALL be present.

2.2.1.13.  distribution

   distribution represents the basic distribution rules of the event.
   The system must adhere to the distribution setting for access control
   and for dissemination of the event.

   distribution is represented by a JSON string. distribution MUST be
   present and be one of the following options:

   0
      Your Organisation Only

   1
      This Community Only

   2
      Connected Communities

   3
      All Communities

   4
      Sharing Group

2.2.1.14.  sharing_group_id

   sharing_group_id represents a human-readable identifier referencing a
   Sharing Group object that defines the distribution of the event, if
   distribution level "4" is set.

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   sharing_group_id is represented by a JSON string and MUST be present.
   If a distribution level other than "4" is chosen the sharing_group_id
   MUST be set to "0".

2.3.  Objects

2.3.1.  Org

   An Org object is composed of an uuid, name and id.

   The uuid represents the Universally Unique IDentifier (UUID)
   [RFC4122] of the organization.  The organization UUID is globally
   assigned to an organization and SHALL be kept overtime.

   The name is a readable description of the organization and SHOULD be
   present.  The id is a human-readable identifier generated by the
   instance and used as reference in the event.

   uuid, name and id are represented as a JSON string. uuid, name and id
   MUST be present.

2.3.1.1.  Sample Org Object

          "Org": {
                  "id": "2",
                  "name": "CIRCL",
                  "uuid": "55f6ea5e-2c60-40e5-964f-47a8950d210f"
                 }

2.3.2.  Orgc

   An Orgc object is composed of an uuid, name and id.

   The uuid MUST be preserved for any updates or transfer of the same
   event.  UUID version 4 is RECOMMENDED when assigning it to a new
   event.  The organization UUID is globally assigned to an organization
   and SHALL be kept overtime.

   The name is a readable description of the organization and SHOULD be
   present.  The id is a human-readable identifier generated by the
   instance and used as reference in the event.

   uuid, name and id are represented as a JSON string. uuid, name and id
   MUST be present.

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2.4.  Attribute

   Attributes are used to describe the indicators and contextual data of
   an event.  The main information contained in an attribute is made up
   of a category-type-value triplet, where the category and type give
   meaning and context to the value.  Through the various category-type
   combinations a wide range of information can be conveyed.

   A MISP document MUST at least includes category-type-value triplet
   described in section "Attribute Attributes".

2.4.1.  Sample Attribute Object

       "Attribute": {
                     "id": "346056",
                     "type": "comment",
                     "category": "Other",
                     "to_ids": false,
                     "uuid": "57f4f6d9-cd20-458b-84fd-109ec0a83869",
                     "event_id": "3357",
                     "distribution": "5",
                     "timestamp": "1475679332",
                     "comment": "",
                     "sharing_group_id": "0",
                     "deleted": false,
                     "value": "Hello world",
                     "SharingGroup": [],
                     "ShadowAttribute": [],
                     "RelatedAttribute": []
                    }

2.4.2.  Attribute Attributes

2.4.2.1.  uuid

   uuid represents the Universally Unique IDentifier (UUID) [RFC4122] of
   the event.  The uuid MUST be preserved for any updates or transfer of
   the same event.  UUID version 4 is RECOMMENDED when assigning it to a
   new event.

   uuid is represented as a JSON string. uuid MUST be present.

2.4.2.2.  id

   id represents the human-readable identifier associated to the event
   for a specific MISP instance.

   id is represented as a JSON string. id SHALL be present.

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2.4.2.3.  type

   type represents the means through which an attribute tries to
   describe the intent of the attribute creator, using a list of pre-
   defined attribute types.

   type is represented as a JSON string. type MUST be present and it
   MUST be a valid selection for the chosen category.  The list of valid
   category-type combinations is as follows:

   Internal reference
      text, link, comment, other

   Targeting data
      target-user, target-email, target-machine, target-org, target-
      location, target-external, comment

   Antivirus detection
      link, comment, text, attachment, other

   Payload delivery
      md5, sha1, sha224, sha256, sha384, sha512, sha512/224, sha512/256,
      ssdeep, imphash, authentihash, pehash, tlsh, filename,
      filename|md5, filename|sha1, filename|sha224, filename|sha256,
      filename|sha384, filename|sha512, filename|sha512/224,
      filename|sha512/256, filename|authentihash, filename|ssdeep,
      filename|tlsh, filename|imphash, filename|pehash, ip-src, ip-dst,
      hostname, domain, email-src, email-dst, email-subject, email-
      attachment, url, user-agent, AS, pattern-in-file, pattern-in-
      traffic, yara, attachment, malware-sample, link, malware-type,
      comment, text, vulnerability, x509-fingerprint-sha1, other

   Artifacts dropped
      md5, sha1, sha224, sha256, sha384, sha512, sha512/224, sha512/256,
      ssdeep, imphash, authentihash, filename, filename|md5,
      filename|sha1, filename|sha224, filename|sha256, filename|sha384,
      filename|sha512, filename|sha512/224, filename|sha512/256,
      filename|authentihash, filename|ssdeep, filename|tlsh,
      filename|imphash, filename|pehash, regkey, regkey|value, pattern-
      in-file, pattern-in-memory, pdb, yara, attachment, malware-sample,
      named pipe, mutex, windows-scheduled-task, windows-service-name,
      windows-service-displayname, comment, text, x509-fingerprint-sha1,
      other

   Payload installation
      md5, sha1, sha224, sha256, sha384, sha512, sha512/224, sha512/256,
      ssdeep, imphash, authentihash, pehash, tlsh, filename,
      filename|md5, filename|sha1, filename|sha224, filename|sha256,

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      filename|sha384, filename|sha512, filename|sha512/224,
      filename|sha512/256, filename|authentihash, filename|ssdeep,
      filename|tlsh, filename|imphash, filename|pehash, pattern-in-file,
      pattern-in-traffic, pattern-in-memory, yara, vulnerability,
      attachment, malware-sample, malware-type, comment, text, x509-
      fingerprint-sha1, other

   Persistence mechanism
      filename, regkey, regkey|value, comment, text, other

   Network activity
      ip-src, ip-dst, hostname, domain, domain|ip, email-dst, url, uri,
      user-agent, http-method, AS, snort, pattern-in-file, pattern-in-
      traffic, attachment, comment, text, x509-fingerprint-sha1, other

   Payload type
      comment, text, other

   Attribution
      threat-actor, campaign-name, campaign-id, whois-registrant-phone,
      whois-registrant-email, whois-registrant-name, whois-registrar,
      whois-creation-date, comment, text, x509-fingerprint-sha1, other

   External analysis
      md5, sha1, sha256, filename, filename|md5, filename|sha1,
      filename|sha256, ip-src, ip-dst, hostname, domain, domain|ip, url,
      user-agent, regkey, regkey|value, AS, snort, pattern-in-file,
      pattern-in-traffic, pattern-in-memory, vulnerability, attachment,
      malware-sample, link, comment, text, x509-fingerprint-sha1, other

   Financial fraud
      btc, iban, bic, bank-account-nr, aba-rtn, bin, cc-number, prtn,
      comment, text, other

   Other
      comment, text, other

   Attributes are based on the usage within their different communities.
   Attributes can be extended on a regular basis and this reference
   document is updated accordingly.

2.4.2.4.  category

   category represents the intent of what the attribute is describing as
   selected by the attribute creator, using a list of pre-defined
   attribute categories.

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   category is represented as a JSON string. category MUST be present
   and it MUST be a valid selection for the chosen type.  The list of
   valid category-type combinations is mentioned above.

2.4.2.5.  to_ids

   to_ids represents whether the attribute is meant to be actionable.
   Actionable defined attributes that can be used in automated processes
   as a pattern for detection in Local or Network Intrusion Detection
   System, log analysis tools or even filtering mechanisms.

   to_ids is represented as a JSON boolean. to_ids MUST be present.

2.4.2.6.  event_id

   event_id represents a human-readable identifier referencing the Event
   object that the attribute belongs to.

   The event_id SHOULD be updated when the event is imported to reflect
   the newly created event's id on the instance.

   event_id is represented as a JSON string. event_id MUST be present.

2.4.2.7.  distribution

   distribution represents the basic distribution rules of the
   attribute.  The system must adhere to the distribution setting for
   access control and for dissemination of the attribute.

   distribution is represented by a JSON string. distribution MUST be
   present and be one of the following options:

   0
      Your Organisation Only

   1
      This Community Only

   2
      Connected Communities

   3
      All Communities

   4
      Sharing Group

   5

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      Inherit Event

2.4.2.8.  timestamp

   timestamp represents a reference time when the attribute was created
   or last modified. timestamp is expressed in seconds (decimal) since
   1st of January 1970 (Unix timestamp).  The time zone MUST be UTC.

   timestamp is represented as a JSON string. timestamp MUST be present.

2.4.2.9.  comment

   comment is a contextual comment field.

   comment is represented by a JSON string. comment MAY be present.

2.4.2.10.  sharing_group_id

   sharing_group_id represents a human-readable identifier referencing a
   Sharing Group object that defines the distribution of the attribute,
   if distribution level "4" is set.

   sharing_group_id is represented by a JSON string and MUST be present.
   If a distribution level other than "4" is chosen the sharing_group_id
   MUST be set to "0".

2.4.2.11.  deleted

   deleted represents a setting that allows attributes to be revoked.
   Revoked attributes are not actionable and exist merely to inform
   other instances of a revocation.

   deleted is represented by a JSON boolean. deleted MUST be present.

2.4.2.12.  data

   data contains the base64 encoded contents of an attachment or a
   malware sample.  For malware samples, the sample MUST be encrypted
   using a password protected zip archive, with the password being
   "infected".

   data is represented by a JSON string in base64 encoding. data MUST be
   set for attributes of type malware-sample and attachment.

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2.4.2.13.  RelatedAttribute

   RelatedAttribute is an array of attributes correlating with the
   current attribute.  Each element in the array represents an JSON
   object which contains an Attribute dictionnary with the external
   attributes who correlate.  Each Attribute MUST include the id,
   org_id, info and a value.  Only the correlations found on the local
   instance are shown in RelatedAttribute.

   RelatedAttribute MAY be present.

2.4.2.14.  ShadowAttribute

   ShadowAttribute is an array of shadow attributes that serve as
   proposals by third parties to alter the containing attribute.  The
   structure of a ShadowAttribute is similar to that of an Attribute,
   which can be accepted or discarded by the event creator.  If
   accepted, the original attribute containing the shadow attribute is
   removed and the shadow attribute is converted into an attribute.

   Each shadow attribute that references an attribute MUST contain the
   containing attribute's ID in the old_id field and the event's ID in
   the event_id field.

2.4.2.15.  value

   value represents the payload of an attribute.  The format of the
   value is dependent on the type of the attribute.

   value is represented by a JSON string. value MUST be present.

2.5.  ShadowAttribute

   ShadowAttributes are 3rd party created attributes that either propose
   to add new information to an event or modify existing information.
   They are not meant to be actionable until the event creator accepts
   them - at which point they will be converted into attributes or
   modify an existing attribute.

   They are similar in structure to Attributes but additionally carry a
   reference to the creator of the ShadowAttribute as well as a
   revocation flag.

2.5.1.  Sample Attribute Object

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"ShadowAttribute":  {
                       "id": "8",
                       "type": "ip-src",
                       "category": "Network activity",
                       "to_ids": false,
                       "uuid": "57d475f1-da78-4569-89de-1458c0a83869",
                       "event_uuid": "57d475e6-41c4-41ca-b450-145ec0a83869",
                       "event_id": "9",
                       "old_id": "319",
                       "comment": "",
                       "org_id": "1",
                       "proposal_to_delete": false,
                       "value": "5.5.5.5",
                       "deleted": false,
                       "Org": {
                           "id": "1",
                           "name": "MISP",
                           "uuid": "568cce5a-0c80-412b-8fdf-1ffac0a83869"
                       }
                   }

2.5.2.  ShadowAttribute Attributes

2.5.2.1.  uuid

   uuid represents the Universally Unique IDentifier (UUID) [RFC4122] of
   the event.  The uuid MUST be preserved for any updates or transfer of
   the same event.  UUID version 4 is RECOMMENDED when assigning it to a
   new event.

   uuid is represented as a JSON string. uuid MUST be present.

2.5.2.2.  id

   id represents the human-readable identifier associated to the event
   for a specific MISP instance.

   id is represented as a JSON string. id SHALL be present.

2.5.2.3.  type

   type represents the means through which an attribute tries to
   describe the intent of the attribute creator, using a list of pre-
   defined attribute types.

   type is represented as a JSON string. type MUST be present and it
   MUST be a valid selection for the chosen category.  The list of valid
   category-type combinations is as follows:

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   Internal reference
      text, link, comment, other

   Targeting data
      target-user, target-email, target-machine, target-org, target-
      location, target-external, comment

   Antivirus detection
      link, comment, text, attachment, other

   Payload delivery
      md5, sha1, sha224, sha256, sha384, sha512, sha512/224, sha512/256,
      ssdeep, imphash, authentihash, pehash, tlsh, filename,
      filename|md5, filename|sha1, filename|sha224, filename|sha256,
      filename|sha384, filename|sha512, filename|sha512/224,
      filename|sha512/256, filename|authentihash, filename|ssdeep,
      filename|tlsh, filename|imphash, filename|pehash, ip-src, ip-dst,
      hostname, domain, email-src, email-dst, email-subject, email-
      attachment, url, user-agent, AS, pattern-in-file, pattern-in-
      traffic, yara, attachment, malware-sample, link, malware-type,
      comment, text, vulnerability, x509-fingerprint-sha1, other

   Artifacts dropped
      md5, sha1, sha224, sha256, sha384, sha512, sha512/224, sha512/256,
      ssdeep, imphash, authentihash, filename, filename|md5,
      filename|sha1, filename|sha224, filename|sha256, filename|sha384,
      filename|sha512, filename|sha512/224, filename|sha512/256,
      filename|authentihash, filename|ssdeep, filename|tlsh,
      filename|imphash, filename|pehash, regkey, regkey|value, pattern-
      in-file, pattern-in-memory, pdb, yara, attachment, malware-sample,
      named pipe, mutex, windows-scheduled-task, windows-service-name,
      windows-service-displayname, comment, text, x509-fingerprint-sha1,
      other

   Payload installation
      md5, sha1, sha224, sha256, sha384, sha512, sha512/224, sha512/256,
      ssdeep, imphash, authentihash, pehash, tlsh, filename,
      filename|md5, filename|sha1, filename|sha224, filename|sha256,
      filename|sha384, filename|sha512, filename|sha512/224,
      filename|sha512/256, filename|authentihash, filename|ssdeep,
      filename|tlsh, filename|imphash, filename|pehash, pattern-in-file,
      pattern-in-traffic, pattern-in-memory, yara, vulnerability,
      attachment, malware-sample, malware-type, comment, text, x509-
      fingerprint-sha1, other

   Persistence mechanism
      filename, regkey, regkey|value, comment, text, other

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   Network activity
      ip-src, ip-dst, hostname, domain, domain|ip, email-dst, url, uri,
      user-agent, http-method, AS, snort, pattern-in-file, pattern-in-
      traffic, attachment, comment, text, x509-fingerprint-sha1, other

   Payload type
      comment, text, other

   Attribution
      threat-actor, campaign-name, campaign-id, whois-registrant-phone,
      whois-registrant-email, whois-registrant-name, whois-registrar,
      whois-creation-date, comment, text, x509-fingerprint-sha1, other

   External analysis
      md5, sha1, sha256, filename, filename|md5, filename|sha1,
      filename|sha256, ip-src, ip-dst, hostname, domain, domain|ip, url,
      user-agent, regkey, regkey|value, AS, snort, pattern-in-file,
      pattern-in-traffic, pattern-in-memory, vulnerability, attachment,
      malware-sample, link, comment, text, x509-fingerprint-sha1, other

   Financial fraud
      btc, iban, bic, bank-account-nr, aba-rtn, bin, cc-number, prtn,
      comment, text, other

   Other
      comment, text, other

   Attributes are based on the usage within their different communities.
   Attributes can be extended on a regular basis and this reference
   document is updated accordingly.

2.5.2.4.  category

   category represents the intent of what the attribute is describing as
   selected by the attribute creator, using a list of pre-defined
   attribute categories.

   category is represented as a JSON string. category MUST be present
   and it MUST be a valid selection for the chosen type.  The list of
   valid category-type combinations is mentioned above.

2.5.2.5.  to_ids

   to_ids represents whether the Attribute to be created if the
   ShadowAttribute is accepted is meant to be actionable.  Actionable
   defined attributes that can be used in automated processes as a
   pattern for detection in Local or Network Intrusion Detection System,
   log analysis tools or even filtering mechanisms.

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   to_ids is represented as a JSON boolean. to_ids MUST be present.

2.5.2.6.  event_id

   event_id represents a human-readable identifier referencing the Event
   object that the ShadowAttribute belongs to.

   The event_id SHOULD be updated when the event is imported to reflect
   the newly created event's id on the instance.

   event_id is represented as a JSON string. event_id MUST be present.

2.5.2.7.  old_id

   old_id represents a human-readable identifier referencing the
   Attribute object that the ShadowAttribute belongs to.  A
   ShadowAttribute can this way target an existing Attribute, implying
   that it is a proposal to modify an existing Attribute, or
   alternatively it can be a proposal to create a new Attribute for the
   containing Event.

   The old_id SHOULD be updated when the event is imported to reflect
   the newly created Attribute's id on the instance.  Alternatively, if
   the ShadowAttribute proposes the creation of a new Attribute, it
   should be set to 0.

   old_id is represented as a JSON string. old_id MUST be present.

2.5.2.8.  timestamp

   timestamp represents a reference time when the attribute was created
   or last modified. timestamp is expressed in seconds (decimal) since
   1st of January 1970 (Unix timestamp).  The time zone MUST be UTC.

   timestamp is represented as a JSON string. timestamp MUST be present.

2.5.2.9.  comment

   comment is a contextual comment field.

   comment is represented by a JSON string. comment MAY be present.

2.5.2.10.  org_id

   org_id represents a human-readable identifier referencing the
   proposal creator's Organisation object.

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   Whilst attributes can only be created by the event creator
   organisation, shadow attributes can be created by third parties.
   org_id tracks the creator organisation.

   org_id is represented by a JSON string and MUST be present.

2.5.2.11.  proposal_to_delete

   proposal_to_delete is a boolean flag that sets whether the shadow
   attribute proposes to alter an attribute, or whether it proposes to
   remove it completely.

   Accepting a shadow attribute with this flag set will remove the
   target attribute.

   proposal_to_delete is a JSON boolean and it MUST be present.  If
   proposal_to_delete is set to true, old_id MUST NOT be 0.

2.5.2.12.  deleted

   deleted represents a setting that allows shadow attributes to be
   revoked.  Revoked shadow attributes only serve to inform other
   instances that the shadow attribute is no longer active.

   deleted is represented by a JSON boolean. deleted SHOULD be present.

2.5.2.13.  data

   data contains the base64 encoded contents of an attachment or a
   malware sample.  For malware samples, the sample MUST be encrypted
   using a password protected zip archive, with the password being
   "infected".

   data is represented by a JSON string in base64 encoding. data MUST be
   set for shadow attributes of type malware-sample and attachment.

2.5.3.  Org

   An Org object is composed of an uuid, name and id.

   The uuid represents the Universally Unique IDentifier (UUID)
   [RFC4122] of the organization.  The organization UUID is globally
   assigned to an organization and SHALL be kept overtime.

   The name is a readable description of the organization and SHOULD be
   present.  The id is a human-readable identifier generated by the
   instance and used as reference in the event.

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   uuid, name and id are represented as a JSON string. uuid, name and id
   MUST be present.

2.5.3.1.  Sample Org Object

          "Org": {
                  "id": "2",
                  "name": "CIRCL",
                  "uuid": "55f6ea5e-2c60-40e5-964f-47a8950d210f"
                 }

2.5.3.2.  value

   value represents the payload of an attribute.  The format of the
   value is dependent on the type of the attribute.

   value is represented by a JSON string. value MUST be present.

2.6.  Tag

   A Tag is a simple method to classify an event with a simple tag name.
   The tag name can be freely chosen.  The tag name can be also chosen
   from a fixed machine-tag vocabulary called MISP taxonomies[[MISP-T]].
   A Tag is represented as a JSON array where each element describes
   each tag associated.  A Tag array SHALL be, at least, at Event level.
   A tag element is described with a name, id, colour and exportable
   flag.

   exportable represents a setting if the tag is kept local or
   exportable to other MISP instances. exportable is represented by a
   JSON boolean. id is a human-readable identifier that references the
   tag on the local instance. colour represents an RGB value of the tag.

   name MUST be present. colour, id and exportable SHALL be present.

2.6.1.  Sample Tag

                       "Tag": [{
                               "exportable": true,
                               "colour": "#ffffff",
                               "name": "tlp:white",
                               "id": "2" }]

3.  Manifest

   MISP events can be shared over an HTTP repository, a file package or
   USB key.  A manifest file is used to provide an index of MISP events

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   allowing to only fetch the recently updated files without the need to
   parse each json file.

3.1.  Format

   A manifest file is a simple JSON file named manifest.json in a
   directory where the MISP events are located.  Each MISP event is a
   file located in the same directory with the event uuid as filename
   with the json extension.

   The manifest format is a JSON object composed of a dictionary where
   the field is the uuid of the event.

   Each uuid is composed of a JSON object with the following fields
   which came from the original event referenced by the same uuid:

   o  info (MUST)

   o  Orgc object (MUST)

   o  analysis (SHALL)

   o  timestamp (MUST)

   o  date (MUST)

   o  threat_level_id (SHALL)

   In addition to the fields originating from the event, the following
   fields can be added:

   o  integrity:sha256 represents the SHA256 value in hexadecimal
      representation of the associated MISP event file to ensure
      integrity of the file.  (SHOULD)

   o  integrity:pgp represents a detached PGP signature [RFC4880] of the
      associated MISP event file to ensure integrity of the file.
      (SHOULD)

   If a detached PGP signature is used for each MISP event, a detached
   PGP signature is a MUST to ensure integrity of the manifest file.  A
   detached PGP signature for a manifest file is a manifest.json.pgp
   file containing the PGP signature.

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3.1.1.  Sample Manifest

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{
  "57c6ac4c-c60c-4f79-a38f-b666950d210f": {
    "info": "Malspam 2016-08-31 (.wsf in .zip) - campaign: Photo",
    "Orgc": {
      "id": "2",
      "name": "CIRCL"
    },
    "analysis": "0",
    "Tag": [
      {
        "colour": "#3d7a00",
        "name": "circl:incident-classification=\"malware\""
      },
      {
        "colour": "#ffffff",
        "name": "tlp:white"
      }
    ],
    "timestamp": "1472638251",
    "date": "2016-08-31",
    "threat_level_id": "3"
  },
  "5720accd-dd28-45f8-80e5-4605950d210f": {
    "info": "Malspam 2016-04-27 - Locky",
    "Orgc": {
      "id": "2",
      "name": "CIRCL"
    },
    "analysis": "2",
    "Tag": [
      {
        "colour": "#ffffff",
        "name": "tlp:white"
      },
      {
        "colour": "#3d7a00",
        "name": "circl:incident-classification=\"malware\""
      },
      {
        "colour": "#2c4f00",
        "name": "malware_classification:malware-category=\"Ransomware\""
      }
    ],
    "timestamp": "1461764231",
    "date": "2016-04-27",
    "threat_level_id": "3"
  }
}

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4.  Implementation

   MISP format is implemented by different software including the MISP
   threat sharing platform and libraries like PyMISP [MISP-P].
   Implementations use the format as an export/import mechanism, staging
   transport format or synchronisation format as used in the MISP core
   platform.  MISP format doesn't impose any restriction on the data
   representation of the format in data-structure of other
   implementations.

5.  Security Considerations

   MISP events might contain sensitive or confidential information.
   Adequate access control and encryption measures shall be implemented
   to ensure the confidentiality of the MISP events.

   Adversaries might include malicious content in MISP events and
   attributes.  Implementation MUST consider the input of malicious
   inputs beside the standard threat information that might already
   include malicious intended inputs.

6.  Acknowledgements

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

7.  Sample MISP file

8.  References

8.1.  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,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122,
              DOI 10.17487/RFC4122, July 2005,
              <http://www.rfc-editor.org/info/rfc4122>.

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

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   [RFC4880]  Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R.
              Thayer, "OpenPGP Message Format", RFC 4880,
              DOI 10.17487/RFC4880, November 2007,
              <http://www.rfc-editor.org/info/rfc4880>.

8.2.  Informative References

   [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
   41, avenue de la gare
   Luxembourg  L-1611
   Luxembourg

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

   Andras Iklody
   Computer Incident Response Center Luxembourg
   41, avenue de la gare
   Luxembourg  L-1611
   Luxembourg

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

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