RFC 5070
The Incident Object Description Exchange Format
3.7. Contact Class
The Contact class describes contact information for organizations and personnel involved in the incident. This class allows for the naming of the involved party, specifying contact information for them, and identifying their role in the incident. People and organizations are treated interchangeably as contacts; one can be associated with the other using the recursive definition of the class (the Contact class is aggregated into the Contact class). The 'type' attribute disambiguates the type of contact information being provided. The inheriting definition of Contact provides a way to relate information without requiring the explicit use of identifiers in the classes or duplication of data. A complete point of contact is derived by a particular traversal from the root Contact class to the leaf Contact class. As such, multiple points of contact might be specified in a single instance of a Contact class. Each child Contact class logically inherits contact information from its ancestors.
+------------------+ | Contact | +------------------+ | ENUM role |<>--{0..1}--[ ContactName ] | STRING ext-role |<>--{0..*}--[ Description ] | ENUM type |<>--{0..*}--[ RegistryHandle ] | STRING ext-type |<>--{0..1}--[ PostalAddress ] | ENUM restriction |<>--{0..*}--[ Email ] | |<>--{0..*}--[ Telephone ] | |<>--{0..1}--[ Fax ] | |<>--{0..1}--[ Timezone ] | |<>--{0..*}--[ Contact ] | |<>--{0..*}--[ AdditionalData ] +------------------+ Figure 7: The Contact Class The aggregate classes that constitute the Contact class are: ContactName Zero or one. ML_STRING. The name of the contact. The contact may either be an organization or a person. The type attribute disambiguates the semantics. Description Zero or many. ML_STRING. A free-form description of this contact. In the case of a person, this is often the organizational title of the individual. RegistryHandle Zero or many. A handle name into the registry of the contact. PostalAddress Zero or one. The postal address of the contact. Email Zero or many. The email address of the contact. Telephone Zero or many. The telephone number of the contact. Fax Zero or one. The facsimile telephone number of the contact. Timezone Zero or one. TIMEZONE. The timezone in which the contact resides formatted according to Section 2.9.
Contact
Zero or many. A Contact instance contained within another Contact
instance inherits the values of the parent(s). This recursive
definition can be used to group common data pertaining to multiple
points of contact and is especially useful when listing multiple
contacts at the same organization.
AdditionalData
Zero or many. A mechanism by which to extend the data model.
At least one of the aggregate classes MUST be present in an instance
of the Contact class. This is not enforced in the IODEF schema as
there is no simple way to accomplish it.
The Contact class has five attributes:
role
Required. ENUM. Indicates the role the contact fulfills. This
attribute is defined as an enumerated list:
1. creator. The entity that generate the document.
2. admin. An administrative contact for a host or network.
3. tech. A technical contact for a host or network.
4. irt. The CSIRT involved in handling the incident.
5. cc. An entity that is to be kept informed about the handling
of the incident.
6. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-role
Optional. STRING. A means by which to extend the role attribute.
See Section 5.1.
type
Required. ENUM. Indicates the type of contact being described.
This attribute is defined as an enumerated list:
1. person. The information for this contact references an
individual.
2. organization. The information for this contact references an
organization.
3. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.
restriction
Optional. ENUM. This attribute is defined in Section 3.2.
3.7.1. RegistryHandle Class
The RegistryHandle class represents a handle into an Internet
registry or community-specific database. The handle is specified in
the element content and the type attribute specifies the database.
+---------------------+
| RegistryHandle |
+---------------------+
| STRING |
| |
| ENUM registry |
| STRING ext-registry |
+---------------------+
Figure 8: The RegistryHandle Class
The RegistryHandle class has two attributes:
registry
Required. ENUM. The database to which the handle belongs. The
default value is 'local'. The possible values are:
1. internic. Internet Network Information Center
2. apnic. Asia Pacific Network Information Center
3. arin. American Registry for Internet Numbers
4. lacnic. Latin-American and Caribbean IP Address Registry
5. ripe. Reseaux IP Europeens
6. afrinic. African Internet Numbers Registry
7. local. A database local to the CSIRT
8. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-registry
Optional. STRING. A means by which to extend the registry
attribute. See Section 5.1.
3.7.2. PostalAddress Class
The PostalAddress class specifies a postal address formatted
according to the POSTAL data type (Section 2.11).
+---------------------+
| PostalAddress |
+---------------------+
| POSTAL |
| |
| ENUM meaning |
| ENUM lang |
+---------------------+
Figure 9: The PostalAddress Class
The PostalAddress class has two attributes:
meaning
Optional. ENUM. A free-form description of the element content.
lang
Required. ENUM. A valid language code per RFC 4646 [7]
constrained by the definition of "xs:language". The
interpretation of this code is described in Section 6.
3.7.3. Email Class
The Email class specifies an email address formatted according to
EMAIL data type (Section 2.14).
+--------------+
| Email |
+--------------+
| EMAIL |
| |
| ENUM meaning |
+--------------+
Figure 10: The Email Class
The Email class has one attribute:
meaning
Optional. ENUM. A free-form description of the element content.
3.7.4. Telephone and Fax Classes
The Telephone and Fax classes specify a voice or fax telephone number
respectively, and are formatted according to PHONE data type
(Section 2.13).
+--------------------+
| {Telephone | Fax } |
+--------------------+
| PHONE |
| |
| ENUM meaning |
+--------------------+
Figure 11: The Telephone and Fax Classes
The Telephone class has one attribute:
meaning
Optional. ENUM. A free-form description of the element content
(e.g., hours of coverage for a given number).
3.8. Time Classes
The data model uses five different classes to represent a timestamp.
Their definition is identical, but each has a distinct name to convey
a difference in semantics.
The element content of each class is a timestamp formatted according
to the DATETIME data type (see Section 2.8).
+----------------------------------+
| {Start| End| Report| Detect}Time |
+----------------------------------+
| DATETIME |
+----------------------------------+
Figure 12: The Time Classes
3.8.1. StartTime
The StartTime class represents the time the incident began.3.8.2. EndTime
The EndTime class represents the time the incident ended.3.8.3. DetectTime
The DetectTime class represents the time the first activity of the incident was detected.3.8.4. ReportTime
The ReportTime class represents the time the incident was reported. This timestamp SHOULD coincide to the time at which the IODEF document is generated.3.8.5. DateTime
The DateTime class is a generic representation of a timestamp. Its semantics should be inferred from the parent class in which it is aggregated.3.9. Method Class
The Method class describes the methodology used by the intruder to perpetrate the events of the incident. This class consists of a list of references describing the attack method and a free form description of the technique. +------------------+ | Method | +------------------+ | ENUM restriction |<>--{0..*}--[ Reference ] | |<>--{0..*}--[ Description ] | |<>--{0..*}--[ AdditionalData ] +------------------+ Figure 13: The Method Class The Method class is composed of three aggregate classes. Reference Zero or many. A reference to a vulnerability, malware sample, advisory, or analysis of an attack technique.
Description
Zero or many. ML_STRING. A free-form text description of the
methodology used by the intruder.
AdditionalData
Zero or many. A mechanism by which to extend the data model.
Either an instance of the Reference or Description class MUST be
present.
The Method class has one attribute:
restriction
Optional. ENUM. This attribute is defined in Section 3.2.
3.9.1. Reference Class
The Reference class is a reference to a vulnerability, IDS alert,
malware sample, advisory, or attack technique. A reference consists
of a name, a URL to this reference, and an optional description.
+------------------+
| Reference |
+------------------+
| |<>----------[ ReferenceName ]
| |<>--{0..*}--[ URL ]
| |<>--{0..*}--[ Description ]
+------------------+
Figure 14: The Reference Class
The aggregate classes that constitute Reference:
ReferenceName
One. ML_STRING. Name of the reference.
URL
Zero or many. URL. A URL associated with the reference.
Description
Zero or many. ML_STRING. A free-form text description of this
reference.
3.10. Assessment Class
The Assessment class describes the technical and non-technical
repercussions of the incident on the CSIRT's constituency.
This class was derived from the IDMEF[17]. +------------------+ | Assessment | +------------------+ | ENUM occurrence |<>--{0..*}--[ Impact ] | ENUM restriction |<>--{0..*}--[ TimeImpact ] | |<>--{0..*}--[ MonetaryImpact ] | |<>--{0..*}--[ Counter ] | |<>--{0..1}--[ Confidence ] | |<>--{0..*}--[ AdditionalData ] +------------------+ Figure 15: Assessment Class The aggregate classes that constitute Assessment are: Impact Zero or many. Technical impact of the incident on a network. TimeImpact Zero or many. Impact of the activity measured with respect to time. MonetaryImpact Zero or many. Impact of the activity measured with respect to financial loss. Counter Zero or more. A counter with which to summarize the magnitude of the activity. Confidence Zero or one. An estimate of confidence in the assessment. AdditionalData Zero or many. A mechanism by which to extend the data model. A least one instance of the possible three impact classes (i.e., Impact, TimeImpact, or MonetaryImpact) MUST be present. The Assessment class has two attributes: occurrence Optional. ENUM. Specifies whether the assessment is describing actual or potential outcomes. The default is "actual" and is assumed if not specified.
1. actual. This assessment describes activity that has occurred.
2. potential. This assessment describes potential activity that
might occur.
restriction
Optional. ENUM. This attribute is defined in Section 3.2.
3.10.1. Impact Class
The Impact class allows for categorizing and describing the technical
impact of the incident on the network of an organization.
This class is based on the IDMEF [17].
+------------------+
| Impact |
+------------------+
| ML_STRING |
| |
| ENUM lang |
| ENUM severity |
| ENUM completion |
| ENUM type |
| STRING ext-type |
+------------------+
Figure 16: Impact Class
The element content will be a free-form textual description of the
impact.
The Impact class has five attributes:
lang
Required. ENUM. A valid language code per RFC 4646 [7]
constrained by the definition of "xs:language". The
interpretation of this code is described in Section 6.
severity
Optional. ENUM. An estimate of the relative severity of the
activity. The permitted values are shown below. There is no
default value.
1. low. Low severity
2. medium. Medium severity
3. high. High severity
completion
Optional. ENUM. An indication whether the described activity was
successful. The permitted values are shown below. There is no
default value.
1. failed. The attempted activity was not successful.
2. succeeded. The attempted activity succeeded.
type
Required. ENUM. Classifies the malicious activity into incident
categories. The permitted values are shown below. The default
value is "other".
1. admin. Administrative privileges were attempted.
2. dos. A denial of service was attempted.
3. file. An action that impacts the integrity of a file or
database was attempted.
4. info-leak. An attempt was made to exfiltrate information.
5. misconfiguration. An attempt was made to exploit a mis-
configuration in a system.
6. policy. Activity violating site's policy was attempted.
7. recon. Reconnaissance activity was attempted.
8. social-engineering. A social engineering attack was
attempted.
9. user. User privileges were attempted.
10. unknown. The classification of this activity is unknown.
11. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-type
Optional. STRING. A means by which to extend the type attribute.
See Section 5.1.
3.10.2. TimeImpact Class
The TimeImpact class describes the impact of the incident on an
organization as a function of time. It provides a way to convey down
time and recovery time.
+---------------------+
| TimeImpact |
+---------------------+
| REAL |
| |
| ENUM severity |
| ENUM metric |
| STRING ext-metric |
| ENUM duration |
| STRING ext-duration |
+---------------------+
Figure 17: TimeImpact Class
The element content is a positive, floating point (REAL) number
specifying a unit of time. The duration and metric attributes will
imply the semantics of the element content.
The TimeImpact class has five attributes:
severity
Optional. ENUM. An estimate of the relative severity of the
activity. The permitted values are shown below. There is no
default value.
1. low. Low severity
2. medium. Medium severity
3. high. High severity
metric
Required. ENUM. Defines the metric in which the time is
expressed. The permitted values are shown below. There is no
default value.
1. labor. Total staff-time to recovery from the activity (e.g.,
2 employees working 4 hours each would be 8 hours).
2. elapsed. Elapsed time from the beginning of the recovery to
its completion (i.e., wall-clock time).
3. downtime. Duration of time for which some provided service(s)
was not available.
4. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-metric
Optional. STRING. A means by which to extend the metric
attribute. See Section 5.1.
duration
Required. ENUM. Defines a unit of time, that when combined with
the metric attribute, fully describes a metric of impact that will
be conveyed in the element content. The permitted values are
shown below. The default value is "hour".
1. second. The unit of the element content is seconds.
2. minute. The unit of the element content is minutes.
3. hour. The unit of the element content is hours.
4. day. The unit of the element content is days.
5. month. The unit of the element content is months.
6. quarter. The unit of the element content is quarters.
7. year. The unit of the element content is years.
8. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-duration
Optional. STRING. A means by which to extend the duration
attribute. See Section 5.1.
3.10.3. MonetaryImpact Class
The MonetaryImpact class describes the financial impact of the
activity on an organization. For example, this impact may consider
losses due to the cost of the investigation or recovery, diminished
productivity of the staff, or a tarnished reputation that will affect future opportunities. +------------------+ | MonetaryImpact | +------------------+ | REAL | | | | ENUM severity | | STRING currency | +------------------+ Figure 18: MonetaryImpact Class The element content is a positive, floating point number (REAL) specifying a unit of currency described in the currency attribute. The MonetaryImpact class has two attributes: severity Optional. ENUM. An estimate of the relative severity of the activity. The permitted values are shown below. There is no default value. 1. low. Low severity 2. medium. Medium severity 3. high. High severity currency Required. STRING. Defines the currency in which the monetary impact is expressed. The permitted values are defined in ISO 4217:2001, Codes for the representation of currencies and funds [14]. There is no default value.3.10.4. Confidence Class
The Confidence class represents a best estimate of the validity and accuracy of the described impact (see Section 3.10) of the incident activity. This estimate can be expressed as a category or a numeric calculation. This class if based upon the IDMEF [17]).
+------------------+ | Confidence | +------------------+ | REAL | | | | ENUM rating | +------------------+ Figure 19: Confidence Class The element content expresses a numerical assessment in the confidence of the data when the value of the rating attribute is "numeric". Otherwise, this element should be empty. The Confidence class has one attribute. rating Required. ENUM. A rating of the analytical validity of the specified Assessment. The permitted values are shown below. There is no default value. 1. low. Low confidence in the validity. 2. medium. Medium confidence in the validity. 3. high. High confidence in the validity. 4. numeric. The element content contains a number that conveys the confidence of the data. The semantics of this number outside the scope of this specification.3.11. History Class
The History class is a log of the significant events or actions performed by the involved parties during the course of handling the incident. The level of detail maintained in this log is left up to the discretion of those handling the incident. +------------------+ | History | +------------------+ | ENUM restriction |<>--{1..*}--[ HistoryItem ] | | +------------------+
Figure 20: The History Class
The class that constitutes History is:
HistoryItem
One or many. Entry in the history log of significant events or
actions performed by the involved parties.
The History class has one attribute:
restriction
Optional. ENUM. This attribute is defined in Section 3.2.
3.11.1. HistoryItem Class
The HistoryItem class is an entry in the History (Section 3.11) log
that documents a particular action or event that occurred in the
course of handling the incident. The details of the entry are a
free-form description, but each can be categorized with the type
attribute.
+-------------------+
| HistoryItem |
+-------------------+
| ENUM restriction |<>----------[ DateTime ]
| ENUM action |<>--{0..1}--[ IncidentId ]
| STRING ext-action |<>--{0..1}--[ Contact ]
| |<>--{0..*}--[ Description ]
| |<>--{0..*}--[ AdditionalData ]
+-------------------+
Figure 21: HistoryItem Class
The aggregate classes that constitute HistoryItem are:
DateTime
One. Timestamp of this entry in the history log (e.g., when the
action described in the Description was taken).
IncidentID
Zero or One. In a history log created by multiple parties, the
IncidentID provides a mechanism to specify which CSIRT created a
particular entry and references this organization's incident
tracking number. When a single organization is maintaining the
log, this class can be ignored.
Contact
Zero or One. Provides contact information for the person that
performed the action documented in this class.
Description
Zero or many. ML_STRING. A free-form textual description of the
action or event.
AdditionalData
Zero or many. A mechanism by which to extend the data model.
The HistoryItem class has three attributes:
restriction
Optional. ENUM. This attribute has been defined in Section 3.2.
action
Required. ENUM. Classifies a performed action or occurrence
documented in this history log entry. As activity will likely
have been instigated either through a previously conveyed
expectation or internal investigation, this attribute is identical
to the category attribute of the Expectation class. The
difference is only one of tense. When an action is in this class,
it has been completed. See Section 3.13.
ext-action
Optional. STRING. A means by which to extend the action
attribute. See Section 5.1.
3.12. EventData Class
The EventData class describes a particular event of the incident for
a given set of hosts or networks. This description includes the
systems from which the activity originated and those targeted, an
assessment of the techniques used by the intruder, the impact of the
activity on the organization, and any forensic evidence discovered.
+------------------+ | EventData | +------------------+ | ENUM restriction |<>--{0..*}--[ Description ] | |<>--{0..1}--[ DetectTime ] | |<>--{0..1}--[ StartTime ] | |<>--{0..1}--[ EndTime ] | |<>--{0..*}--[ Contact ] | |<>--{0..1}--[ Assessment ] | |<>--{0..*}--[ Method ] | |<>--{0..*}--[ Flow ] | |<>--{0..*}--[ Expectation ] | |<>--{0..1}--[ Record ] | |<>--{0..*}--[ EventData ] | |<>--{0..*}--[ AdditionalData ] +------------------+ Figure 22: The EventData Class The aggregate classes that constitute EventData are: Description Zero or more. ML_STRING. A free-form textual description of the event. DetectTime Zero or one. The time the event was detected. StartTime Zero or one. The time the event started. EndTime Zero or one. The time the event ended. Contact Zero or more. Contact information for the parties involved in the event. Assessment Zero or one. The impact of the event on the target and the actions taken. Method Zero or more. The technique used by the intruder in the event.
Flow
Zero or more. A description of the systems or networks involved.
Expectation
Zero or more. The expected action to be performed by the
recipient for the described event.
Record
Zero or one. Supportive data (e.g., log files) that provides
additional information about the event.
EventData
Zero or more. EventData instances contained within another
EventData instance inherit the values of the parent(s); this
recursive definition can be used to group common data pertaining
to multiple events. When EventData elements are defined
recursively, only the leaf instances (those EventData instances
not containing other EventData instances) represent actual events.
AdditionalData
Zero or more. An extension mechanism for data not explicitly
represented in the data model.
At least one of the aggregate classes MUST be present in an instance
of the EventData class. This is not enforced in the IODEF schema as
there is no simple way to accomplish it.
The EventData class has one attribute:
restriction
Optional. ENUM. This attribute is defined in Section 3.2.
3.12.1. Relating the Incident and EventData Classes
There is substantial overlap in the Incident and EventData classes.
Nevertheless, the semantics of these classes are quite different.
The Incident class provides summary information about the entire
incident, while the EventData class provides information about the
individual events comprising the incident. In the most common case,
the EventData class will provide more specific information for the
general description provided in the Incident class. However, it may
also be possible that the overall summarized information about the
incident conflicts with some individual information in an EventData
class when there is a substantial composition of various events in
the incident. In such a case, the interpretation of the more
specific EventData MUST supersede the more generic information
provided in IncidentData.
3.12.2. Cardinality of EventData
The EventData class can be thought of as a container for the properties of an event in an incident. These properties include: the hosts involved, impact of the incident activity on the hosts, forensic logs, etc. With an instance of the EventData class, hosts (i.e., System class) are grouped around these common properties. The recursive definition (or instance property inheritance) of the EventData class (the EventData class is aggregated into the EventData class) provides a way to related information without requiring the explicit use of unique attribute identifiers in the classes or duplicating information. Instead, the relative depth (nesting) of a class is used to group (relate) information. For example, an EventData class might be used to describe two machines involved in an incident. This description can be achieved using multiple instances of the Flow class. It happens that there is a common technical contact (i.e., Contact class) for these two machines, but the impact (i.e., Assessment class) on them is different. A depiction of the representation for this situation can be found in Figure 23. +------------------+ | EventData | +------------------+ | |<>----[ Contact ] | | | |<>----[ EventData ]<>----[ Flow ] | | [ ]<>----[ Assessment ] | | | |<>----[ EventData ]<>----[ Flow ] | | [ ]<>----[ Assessment ] +------------------+ Figure 23: Recursion in the EventData Class3.13. Expectation Class
The Expectation class conveys to the recipient of the IODEF document the actions the sender is requesting. The scope of the requested action is limited to purview of the EventData class in which this class is aggregated.
+-------------------+ | Expectation | +-------------------+ | ENUM restriction |<>--{0..*}--[ Description ] | ENUM severity |<>--{0..1}--[ StartTime ] | ENUM action |<>--{0..1}--[ EndTime ] | STRING ext-action |<>--{0..1}--[ Contact ] +-------------------+ Figure 24: The Expectation Class The aggregate classes that constitute Expectation are: Description Zero or many. ML_STRING. A free-form description of the desired action(s). StartTime Zero or one. The time at which the action should be performed. A timestamp that is earlier than the ReportTime specified in the Incident class denotes that the expectation should be fulfilled as soon as possible. The absence of this element leaves the execution of the expectation to the discretion of the recipient. EndTime Zero or one. The time by which the action should be completed. If the action is not carried out by this time, it should no longer be performed. Contact Zero or one. The expected actor for the action. The Expectations class has four attributes: restriction Optional. ENUM. This attribute is defined in Section 3.2. severity Optional. ENUM. Indicates the desired priority of the action. This attribute is an enumerated list with no default value, and the semantics of these relative measures are context dependent. 1. low. Low priority 2. medium. Medium priority 3. high. High priority
action
Optional. ENUM. Classifies the type of action requested. This
attribute is an enumerated list with no default value.
1. nothing. No action is requested. Do nothing with the
information.
2. contact-source-site. Contact the site(s) identified as the
source of the activity.
3. contact-target-site. Contact the site(s) identified as the
target of the activity.
4. contact-sender. Contact the originator of the document.
5. investigate. Investigate the systems(s) listed in the event.
6. block-host. Block traffic from the machine(s) listed as
sources the event.
7. block-network. Block traffic from the network(s) lists as
sources in the event.
8. block-port. Block the port listed as sources in the event.
9. rate-limit-host. Rate-limit the traffic from the machine(s)
listed as sources in the event.
10. rate-limit-network. Rate-limit the traffic from the
network(s) lists as sources in the event.
11. rate-limit-port. Rate-limit the port(s) listed as sources in
the event.
12. remediate-other. Remediate the activity in a way other than
by rate limiting or blocking.
13. status-triage. Conveys receipts and the triaging of an
incident.
14. status-new-info. Conveys that new information was received
for this incident.
15. other. Perform some custom action described in the
Description class.
16. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-action
Optional. STRING. A means by which to extend the action
attribute. See Section 5.1.
3.14. Flow Class
The Flow class groups related the source and target hosts.
+------------------+
| Flow |
+------------------+
| |<>--{1..*}--[ System ]
+------------------+
Figure 25: The Flow Class
The aggregate class that constitutes Flow is:
System
One or More. A host or network involved in an event.
The Flow System class has no attributes.
3.15. System Class
The System class describes a system or network involved in an event.
The systems or networks represented by this class are categorized
according to the role they played in the incident through the
category attribute. The value of this category attribute dictates
the semantics of the aggregated classes in the System class. If the
category attribute has a value of "source", then the aggregated
classes denote the machine and service from which the activity is
originating. With a category attribute value of "target" or
"intermediary", then the machine or service is the one targeted in
the activity. A value of "sensor" dictates that this System was part
of an instrumentation to monitor the network.
+---------------------+ | System | +---------------------+ | ENUM restriction |<>----------[ Node ] | ENUM category |<>--{0..*}--[ Service ] | STRING ext-category |<>--{0..*}--[ OperatingSystem ] | STRING interface |<>--{0..*}--[ Counter ] | ENUM spoofed |<>--{0..*}--[ Description ] | |<>--{0..*}--[ AdditionalData ] +---------------------+ Figure 26: The System Class The aggregate classes that constitute System are: Node One. A host or network involved in the incident. Service Zero or more. A network service running on the system. OperatingSystem Zero or one. The operating system running on the system. Counter Zero or more. A counter with which to summarize properties of this host or network. Description Zero or more. ML_STRING. A free-form text description of the System. AdditionalData Zero or many. A mechanism by which to extend the data model. The System class has five attributes: restriction Optional. ENUM. This attribute is defined in Section 3.2. category Required. ENUM. Classifies the role the host or network played in the incident. The possible values are: 1. source. The System was the source of the event. 2. target. The System was the target of the event.
3. intermediate. The System was an intermediary in the event.
4. sensor. The System was a sensor monitoring the event.
5. infrastructure. The System was an infrastructure node of
IODEF document exchange.
6. ext-value. An escape value used to extend this attribute.
See Section 5.1.
ext-category
Optional. STRING. A means by which to extend the category
attribute. See Section 5.1.
interface
Optional. STRING. Specifies the interface on which the event(s)
on this System originated. If the Node class specifies a network
rather than a host, this attribute has no meaning.
spoofed
Optional. ENUM. An indication of confidence in whether this
System was the true target or attacking host. The permitted
values for this attribute are shown below. The default value is
"unknown".
1. unknown. The accuracy of the category attribute value is
unknown.
2. yes. The category attribute value is probably incorrect. In
the case of a source, the System is likely a decoy; with a
target, the System was likely not the intended victim.
3. no. The category attribute value is believed to be correct.
(page 42 continued on part 3)
