Security Area B.-C. Boesch
Internet Draft independent
Intended status: Experimental February 28, 2016
Expires: August 2016
Intrusion Detection Parametrization Exchange Format (IDPEF)
draft-boesch-idxp-idpef-04.txt
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Abstract
The Intrusion Detection Parametrization Exchange Format (IDPEF)
defines data formats and exchange procedures to standardize
parametrization information exchange within intrusion detection and
response systems from a Manager to an Analyzer.
This Internet-Draft describes a data model to represent
parametrization information of intrusion detection system entities,
and explains the rationale for using this model. An implementation
of the data model in the Extensible Markup Language (XML) is
presented, a XML Document Type Definition is developed, and
parametrization examples are provided.
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Table of Contents
1. Introduction ................................................ 6
1.1. Intention of this Format................................ 6
1.2. Structure of this Document.............................. 7
1.3. Rationale for IDPEF..................................... 7
1.3.1. Problems Addressed by the Parametrization Data Model8
1.3.2. Data Model Design Focus............................ 9
1.4. Architecture Assumptions................................ 9
1.5. Focus of Format........................................ 11
1.6. Parametrization Methodology............................ 11
2. The Communication Proceeding................................ 12
2.1. Parametrization Communication.......................... 12
2.2. Version Update on Hierarchical Lower IDS-Entities...... 13
3. The IDPEF XML Implementation................................ 14
3.1. Notational Conventions and Formatting Issues........... 15
3.2. IDPEF XML Documents.................................... 16
3.2.1. Character Data Processing in IDPEF................ 16
3.2.2. Languages in IDPEF................................ 16
3.2.3. The Document Header - The XML Declaration......... 16
3.3. IDPEF Data Types....................................... 17
3.4. Case-Sensitivity....................................... 17
4. The IDPEF Parametrization Data Model........................ 17
4.1. Overview .............................................. 17
4.2. Message Nodes ......................................... 18
4.2.1. IDPEF-Message..................................... 18
4.2.2. The Entity Section................................ 20
4.2.2.1. network...................................... 23
4.2.2.2. address...................................... 25
4.2.2.3. location..................................... 26
4.2.2.4. contact...................................... 27
4.2.2.5. fservice..................................... 28
4.2.2.6. tadmin....................................... 29
4.2.3. The Update Section................................ 29
4.2.3.1. update-file.................................. 30
4.2.3.2. data ........................................ 32
4.2.4. The Alert Section................................. 32
4.2.4.1. group........................................ 32
4.2.4.1.1. event................................... 33
4.2.4.1.1.1. connection......................... 35
4.2.4.1.1.2. system............................. 37
4.2.4.1.1.3. ipara.............................. 37
4.2.4.1.2. react................................... 38
5. Extending the IDPEF ........................................ 39
6. Special Considerations...................................... 40
6.1. XML Validity and Well-Formed........................... 40
6.2. Unrecognized XML Tags.................................. 41
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7. Security Considerations..................................... 41
7.1. Privacy Considerations................................. 42
7.2. Systems Security Issues................................ 43
7.3. Communications Security Issues......................... 44
7.3.1. Passive Attacks................................... 44
7.3.1.1. Confidentiality Violations (Eavesdropping)... 44
7.3.1.2. Password Sniffing............................ 45
7.3.1.3. Offline Cryptographic Attacks................ 45
7.3.2. Active Attacks.................................... 45
7.3.2.1. Replay Attacks............................... 45
7.3.2.2. Message Insertion............................ 45
7.3.2.3. Message Deletion............................. 45
7.3.2.4. Message Modification......................... 46
7.3.2.5. Man-In-The-Middle............................ 46
7.3.3. Topological Issues................................ 46
7.3.4. Denial of Service................................. 46
7.4. Digital Signatures..................................... 46
8. IANA Considerations ........................................ 46
9. Conclusions ................................................ 47
10. Acknowledgments ........................................... 47
APPENDIX A: Examples .......................................... 48
A.1. Feature-Requests....................................... 48
A.1.1. Global Feature-Request............................ 48
A.1.2. Entity Feature-Request............................ 48
A.1.3. Single Attribute Request.......................... 48
A.1.4. Single Alert-Request (Port-Scan).................. 49
A.1.5. Multiple Alert Request............................ 49
A.1.6. Global Alert-Request.............................. 50
A.1.7. Multiple Global Alert-Request..................... 50
A.1.8. Global Alert-Request to sensor with individual IDPEF
Port .................................................... 50
A.2. Feature-Replies........................................ 51
A.2.1. Global Feature-Reply.............................. 51
A.2.2. Version-Reply..................................... 55
A.2.3. Single Alert Feature-Reply (Port-Scan)............ 55
A.3. Entity Information Update.............................. 56
A.4. Analyzer-Update........................................ 59
A.4.1. Single Update..................................... 59
A.4.2. Multiple Updates and Notifications................ 60
A.4.3. Single Backup-Request............................. 61
A.4.4. Single Backup-Reply............................... 62
A.4.5. Single Backup-Restore............................. 62
A.5. Alert Parametrization.................................. 63
A.5.1. Single Parameter-Update (Port-Scan)............... 63
A.5.2. Multiple Parameter Update......................... 64
APPENDIX B: The IDPEF Document Type Definition (Normative)..... 67
APPENDIX C: The IDPEF Schema Definition (Non-normative)........ 83
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APPENDIX D: Change History.................................... 106
11. References ............................................... 107
11.1. Normative References................................. 107
11.2. Informative References............................... 108
Intellectual Property Statement............................... 108
D.1.1. Author's Address................................. 108
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1. Introduction
In examples, "C:" and "S:" indicate lines sent by the client and
server respectively.
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 [1].
In this document, these words will appear with that interpretation
only when in ALL CAPS. Lower case uses of these words are not to be
interpreted as carrying RFC-2119 significance.
In this document, the characters ">>" preceding an indented line(s)
indicates a compliance requirement statement using the key words
listed above. This convention aids reviewers in quickly identifying
or finding the explicit compliance requirements of this RFC.
1.1. Intention of this Format
The Intrusion Detection Parametrization Exchange Format (IDPEF) is
intended to be a standard data format to parametrize Intrusion
Detection Systems (IDS). The development of this standardized format
and the Intrusion Detection Message Exchange Format (IDMEF) [2] are
enabling in combination interoperability among commercial, open
source, and research systems, allowing users to mix-and-match the
deployment of these systems according to their strong and weak
points to obtain an optimal IDS implementation.
The most obvious place to implement IDPEF is in the data channel
between a Manager and an Analyzer of an IDS within this data channel
where the Manager sends the configuration parameters to the
Analyzers. But there are other places where the IDPEF can be useful:
o Combination of specialized IDS like application-IDS combined with
server-IDS, WLAN-IDS and/or network-IDS to one functional
interacting meta-IDS.
o Management of different IDS vendors with one central management
interface.
o Interaction of different IDS by using IDPEF and IDMEF.
o A common data exchange format would make it easier for different
organizations (users, vendors, response teams, etc.) to not only
exchange data, but also communicate about it.
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o The diversity of uses for the IDPEF needs to be considered when
selecting its method of implementation.
o Parametrization backups and restore of network basic configured
(connected and reachable) IDS entities.
o For a communication between a Manager and a Manager in a multi-
stage management architecture.
1.2. Structure of this Document
The remaining paper is organized as follows: The rest of section 1
is focused on the problems that will be addressed by IDPEF,
architectural assumptions and the parametrization methodology.
Section 2 defines basic communication procedures. General XML
conventions for IDPEF are set out in section 3. The IDPEF data model
and its nodes including each single attribute are defined in section
4. Extending of IDPEF and special considerations are set out in the
sections 5 and 6. Subsequent the sections 7 to 10 include IANA
considerations, a short conclusion and acknowledgements.
Appendix A provides some examples for IDPEF in such a way that
unfamiliar readers are able to understand this document better.
Appendix B shows the DTD of IDPEF and a non-normative XML Schema
Definition of IDPEF is set out in Appendix C.
1.3. Rationale for IDPEF
Methods of hacking are changing over periods of time and become more
and more complex. As a result of this, techniques are developed to
raise interoperability of IDS. One part is a standardized
signalizing format to collect event messages of different IDS-
entities. The Intrusion Detection Exchange Format Working Group
(IDWG) has standardized the communication between Analyzer and
Manager with the Intrusion Detection eXchange Protocol (IDXP) [4].
As data format for event signalization from Analyzer to Manager the
Intrusion Detection Message Exchange Format (IDMEF) [2] was defined.
Today, IDS are still operating in encapsulated IT-landscapes. Many
vendors provide IDS-functionalities in their network-components or
applications and IDS-vendors focus their intrusion detection
products to special services. Vendor-dependent tools and
configurations are still needed for administration. This is a big
barrier for an extensive IDS-integration in complex environments. It
is important to standardize the communication and data exchange
between Manager and Analyzer for administration and operations, to
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combine IDS-Analyzers with its Sensors of different vendors and
integrate them into one IDS.
Continuative of IDMEF, an exchange format for administration of IDS
has to standardize the communication from Manager to Analyzer. As
result a fully standardized communication between Managers and
Analyzers enhance interoperability and integration of different IDS.
As result, management front ends will become independent to IDS-
Analyzers.
1.3.1. Problems Addressed by the Parametrization Data Model
The data model addresses several problems associated with
representing intrusion detection parameters:
o Potential intrusion detection environments are very different.
IDS are more and more specialized. Some Analyzers detect attacks
by analyzing network traffic; others use operating system logs or
application audit trail information. The combination of different
specialized IDS, different vendors and/or analyzing techniques
will be more and more important. Interaction of different IDS
and/or vendors is not trivial, because parametrization
information and formats are vendor-specific. The data model that
represents different parametrization information MUST be highly
standardized, but has to be also so flexible to support different
needs of Analyzers and vendors.
o Large enterprises have several security specialists with
different focuses. The working focus of these security
specialists requires different competences. Organizational upper
security groups make regulations for their work. These groups
have to handle different configuration structures today. A
standardized parametrization format makes it easier to exchange
and auditing working results between IDS security specialists
with different vendor focus.
o Administrators are working with several specialized IDS-
parametrization interfaces, sometimes distributed on separate
systems. A standardized parametrization format helps to develop
independent and consistent administration interfaces on one
hardware platform. Administrators are then able to parametrize
IDS of different vendors and analyzing levels by using one
administration interface. As result, the best administration
interface for the operations focus could be selected.
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o A standardized communication allows combining several vendors and
IDS-entities to operate like one IDS. The best fitting Analyzer
could be integrated in the solution.
o Research prototypes and specialized IDS like VoIP-IDS are able to
be better integrated in existing IDS-architectures. Research
results are better portable and interoperability of dedicate
research-projects, like IDS management usability, alert
correlations or automated signature generation [13], will be
enhanced.
1.3.2. Data Model Design Focus
The data model is designed to provide standardized parametrization
for IDS entities. It allows together with IDMEF to combine IDS-
entities of different vendors and analyzing levels to one meta-IDS.
IDPEF provides a closed solution together with IDMEF. Therefore
IDPEF provide at least parameters that are necessary for IDMEF.
The data model design is focused on several IDS entities, their
individual parameter structure and the feature set.
Structure and format of the data model MUST be unambiguous. The
information parameters to an event vary by the event itself and its
characterizing parameters. For example, port-scans or ICMP-floods
need a time-interval and a quantity of packets (port-requests resp.
icmp-packets) to characterize an intrusion. Also the event-name
varies from vendor to vendor and it SHOULD be directly set as
parameter value. Parameters of an Analyzer are individual and have
to be requested by a general parameter request.
This work is focused to standardize parametrization data and format
to enhance the interoperability of IDS.
1.4. Architecture Assumptions
Figure 1 is an enhanced illustration of functional IDS-entities. It
illustrates the intrusion detection entities as defined in [3] and
their relationships. Not every IDS has all of these separate
entities exactly as shown. Some IDS combine these components into a
single module; some will have multiple instances of single modules.
Based on a Data Source the Activity will be recognized and the
Sensor examines necessary Event information and sends it to the
Analyzer. The Analyzer checks the Event information against his
Security Policy and database. The Manager is the entity, which acts
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as single point of administration for the complete system. It
provides the Security Policy, receives the Event notifications and
coordinates Response entities which could be separated from the
identifying Analyzer.
+----------+
|DataSource|----+--Activity------+
+----------+ | |
A V V
| +------+ +------+
Reaction |Sensor| |Sensor|
| +------+ +------+
| | A | A
| Event | Event |
| | Config | Config
| V | V |
| +--------+ +--------+
| |Analyzer| |Analyzer|
| +--------+ +--------+
| | A A |
+--------+ | | | |
|Response| IDMEF IDPEF IDPEF IDMEF
+--------+ | +-+-------+-+ |
A +----->|Manager|<------+
+--------------+-------+
A | A
+---------------+ | |
| | |
+--------+ | | +-------------+
|Operator|<-Notify--+ +----|Administrator|
+--------+ Security +-------------+
| Policy A
| |
+--Security Process-------------+
Figure 1 Relationship of IDS entities.
For the purposes of this document, we assume that the Analyzer and
the Manager are separate components, and that they are communicating
pair wise across a TCP/IP network. No other form of communication
between these entities is contemplated in this document, and no
other use of IDPEF is considered. As transport protocol for IDPEF
the IDXP [4] will be used.
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The following points SHOULD NOT matter for the integration:
o Whether Sensor and Analyzer are integrated or separated.
o Whether Analyzer and Manager are isolated, or embedded in some
large hierarchy or distributed mesh of components.
o Whether the Manager is used for configuration only or
additionally used for notification and/or alert-correlation.
o Whether a component might act as an Analyzer with respect to one
component, while also acting as a Manager with respect to
another.
o Analyzers are homogeneous or mixed by multiple vendors or types.
1.5. Focus of Format
The parametrization format is not designed to be used for initial
setup or basic configuration of new/replaced hardware. The focus of
the parametrization format is to administer and operate different
IDS-applications from one instance and by one user front end.
The format is not intent for signalization. Focus is the
administration with parametrization and parametrization request of
different IDS-applications with a standardized procedure.
The format MUST NOT be designed to create signature or anomaly
pattern. This information has to be created external and uploaded as
update file.
1.6. Parametrization Methodology
IDS compare Activity against a reference database. References
consist of a baseline part and a customizing part. The baseline part
describes the event itself (intrusion activity, vulnerability or
baseline). The references will be customized by baseline part to the
individual implementation. For example, a SYN-flood contains in the
baseline part the attack description. In this case, the TCP/IP
protocol with a set SYN-flag. The customizing part defines a
threshold and a time interval for the individual implementation of
the event. As result, the SYN-request (attack description) has to
occur more than 200 times (threshold) within 1 second (time
interval) to cause a SYN-flood signalization. The baseline part of a
rule is vendor-specific and depends on the internal processing of
Sensor and Analyzer. Therefore it is out of scope for
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parametrization. IDPEF customizes the vendor-specific baseline-part
to the individual implementation of the IDS entity.
2. The Communication Proceeding
The communication proceeding has to work in different IDS architec-
tures. The transport protocol IDXP [4] is responsible for transport
and grants appropriate security. The basic communication proceeding
within IDXP for the format exchange is described in detail here.
Protection of the communication and the exchanged content between
IDS entities is focus by the transport protocol e.g. IDXP [4]. At
least TLS 1.2 [11] and password protection of SASL [12] MUST be
supported. These are not part of the communication proceeding of
IDPEF, but MUST be granted by the transport protocol.
The following points do not have influence on communication and
format:
o Different analyzing techniques
o Mixed feature sets, versions and/or vendors
o Different sensor types
o Parametrization status of Sensors if they are completely or only
partial or not parameterized or have a mix of parametrization
states.
o If a Manager parameterize an Analyzer directly or over a second
Manager.
2.1. Parametrization Communication
A change of the Manager SHOULD be done with minimal impact and
expenditure of work time. The Manager does not keep any feature or
parameter information of Analyzers after the parametrization
session. An information request is a good way to allow more than one
Manager to administrate individual Analyzers. The parametrization
proceeds global like:
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Manager: Analyzer:
selection of
Analyzer
---- begin of OPTIONAL request ----
-------parameter-request------> preparation of
IDPEF response
<-------parameter-reply--------
---- end of OPTIONAL request ----
change of
parameters
-------parameter-update-------> update of para-
meters in the
Analyzer
parametrization- <-------parameter-reply--------
check
2.2. Version Update on Hierarchical Lower IDS-Entities
The parametrization format has to support update of hierarchical
lower IDS entities i.e. updates from a Manager to an Analyzer.
Updates will be terminated to a time specification - derivate
absolute (e.g. 23:00) or relative terminations (e.g. +02:00) are
possible. An update file numeration defines the update order.
The update MUST be checked after every update execution and an
update status MUST be send. If an update execution fails, all
following updates SHOULD set out and not be executed. A notification
SHOULD be sent for each update file if the update processing is
canceled. Updates will be applied like:
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Manager: Analyzer:
Version update
Initialization
---- begin of OPTIONAL request ----
-------version request-------->
<-------version reply----------
---- end of OPTIONAL request ----
Update preparation
Selection of files
schedule of update
-------update information------>
----------update files---------> Update termination
Update execution
<--update status notification-- Update check
signalization of (outside of IDPEF)
update status
3. The IDPEF XML Implementation
The IDPEF implementation uses a Document Type Definition (DTD) to
describe XML documents. The XML solution was primary selected,
because it provides a closed solution together with IDMEF.
A widely spread and powerful used standard is XML and its
flexibility makes it a good choice for applications, also for
implementing the IDPEF as well. Other, more specific reasons for
choosing XML to implement the IDPEF are:
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o Software tools for processing XML documents are widely available,
as commercial and open source version. Numerous tools and
programming interfaces for parsing and/or validating XML are
available in a variety of languages. Widespread access to tools
makes adoption of the IDPEF by product developers easier and
faster. Web technologies like Java Script enable an easy
processing of XML.
o XML supports fully internationalization and localization for IT
solutions that cross political and/or cultural boarders. XML
enables a global usage to parameterize the Analyzer to the
individual implementation and to maintain the IDS in operations.
UTF-8 and UTF-16 make XML applications compatible with these
common character encodings.
o XML also provides support for specifying, on a per-element basis,
the language in which the element's content is written, making
IDPEF easy to adapt to "Natural Language Support" versions of a
product.
o XML is free and has no license, license fees or royalties.
o XML is human readable. Security teams are able to revise the
parametrization or publish specification guidelines for IDS.
3.1. Notational Conventions and Formatting Issues
The IDPEF description bases on three specifications:
o The data-model bases on a Unified Modeling Language description.
o XML describes the markup used in IDPEF documents
o Documents are represented in IDPEF markup.
In Appendix A these notations will be described in sufficient detail
by examples in a way that unfamiliar readers are able to understand
the document. These descriptions are not comprehensive. They only
cover the components of the notations used by the data model and
document format.
Several document formatting issues will be shown in Appendix A
(examples) and Appendix C. These will be applying to XML documents,
including formats for particular data types, special character and
white space processing, character sets and languages.
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3.2. IDPEF XML Documents
This section describes basic IDPEF XML document formatting rules.
Most of these rules are based of rules for formatting XML documents.
3.2.1. Character Data Processing in IDPEF
The character processing was already defined for IDMEF [2], and will
be also used analogue for IDPEF. This section recapitulates it here
for better understanding:
IDPEF compliant applications and messages SHOULD use the character
encodings UTF-8 or UTF-16 only to grant portability. If no encoding
is specified for an IDPEF message, UTF-8 will be assumed, consistent
with the XML standard. At least UTF-8 MUST be supported. Not more
than UTF-8 and UTF-16 SHOULD be used.
IDPEF documents, encoded in UTF-16, MUST begin with the Byte Order
Mark. This is consistent to ISO/IEC 10646 Annex E and Unicode
Appendix B (the "ZERO WIDTH NO-BREAK SPACE" character, #xFEFF).
It is RECOMMENDED that IDPEF compliant applications use the entity
form (section 4.1 of [9]) of the characters '&', ,'<', '>', '"', and
''' (single-quote) whenever writing these characters in data, to
avoid any possibility of misinterpretation [2].
Analogue to the IDMEF specification, the "xml:space" attribute has
to be supported for all IDPEF elements for white space processing
[6].
3.2.2. Languages in IDPEF
The language of the content is encoded and has to be specified in
IDPEF compliant communication. This will be done in a generally way
by applying the attribute "xml:lang" for the top-level element [8].
All other elements will inherit that definition else the language
has to be specified separately for a single element branch. This
specification is set for the single/data record.
3.2.3. The Document Header - The XML Declaration
IDPEF documents will be exchanged between IDPEF compliant
applications. The exchange begins with an XML declaration, followed
by the used XML version. Specification of the used encoding is
RECOMMENDED.
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Each XML document contains a Document Type Declaration (DTD). The
DTD represents significant overhead by bandwidth consume and
performance for XML processing to an IDPEF compliant parametrization
message. To reduce these negatives Analyzers and Managers agree on a
particular DTD via a local reference to the accessing Manager.
Therefore IDPEF messages have to as example start with:
3.3. IDPEF Data Types
XML is a text formatting language and all data will be expressed as
"text" (as opposed to "binary") within an XML IDPEF message, except
it is explicate declared here.
Each data type in the model has specific formatting requirements in
an XML IDPEF message. The data types are Integers, Real Numbers,
Bytes, Enumerated Types, Date Time Strings [7], Port Lists and also
Characters and Strings which are already defined in the IDMEF data
model specification [2].
3.4. Case-Sensitivity
All values are not case-sensitive, except it will be explicit
defined here.
4. The IDPEF Parametrization Data Model
This section illustrates the structure of the IDPEF parametrization
and the relationship between single elements. The individual
elements are explained in detail in the respective section of the
parametrization nodes.
The IDPEF parametrization model describes only the node structure of
the parametrization information. The communication procedure was
already described in section 2.
4.1. Overview
The structure of the IDPEF core components is displayed in figure 2.
The top level node (root node) is called "IDPEF-Message".
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The "IDPEF-Message" node is structured in the three sections
"entity", "alert" and "update". Each section focuses on detailed
parametrization information for global analyzer information, event
parametrization and updates.
+------------------------------------------------------------+
| IDPEF-Message |
+------------------------------------------------------------+
A A A
| | |
V V V
+------------------+ +-----------------+ +-----------------+
| entity | | alert | | update |
+------------------+ +-----------------+ +-----------------+
| +-------------+ | +------------+ | +------------+
+->| network | +->| group | +->| updatefile |
| +-------------+ +------------+ +------------+
| +---------+ |
| +-------------+ | +-----------+ V
+->| location | +--->| event | +----------+
| +-------------+ | +-----------+ | data |
| | | +-------+ +----------+
| V | |
| +---------+ | | +------------+
| | address |<--+ | +->| connection |
| +---------+ | | | +------------+
| +---------+ | | | +------------+
| | contact |<--+ | +->| system |
| +---------+ | | | +------------+
| | | | +------------+
| | | +->| ipara |
| +-------------+ | | +------------+
+->| tadmin |-+ |
| +-------------+ | |
| +-------------+ | | +------------+
+->| fservice |-+ +--->| react |
+-------------+ +------------+
Figure 2 Overview of IDPEF data model
4.2. Message Nodes
4.2.1. IDPEF-Message
The IDPEF-Message node is the top-level of the IDPEF data model. All
IDPEF parametrization nodes are child nodes of the IDPEF-Message
node. It is the root node of all IDPEF-Messages as well as the IDPEF
DTD. The root node is represented in the IDPEF DTD as:
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This node includes the attributes:
format
REQUIRED: The format attribute defines the type of data contents.
Possible values are "request", "reply" or "update".
errorcode
OPTIONAL: RECOMMENDED to be set in case of a reply:
100: ok
200: Request or Update not valid
250: Request or Update not well-formed
300: Internal processing error by the XML
400: Activation of new parameters failed, restart with
old parametrization.
device
REQUIRED: This attribute defines on which device the
parametrization has to be applied. This attribute supports multi-
hop parametrization. In case of a change of "analyzer-ID"/name in
the entity section the old attribute value has to be used. In case
of a bulk update, the devices are separated by comma (,). In case
of a port other than the standard port the port will be specified
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by a double point (:) after the device name (i.e.
analyzer.example.com:603 or 192.168.2.1:603).
4.2.2. The Entity Section
The "entity" node specifies the IDS entity. It includes basic
information about the entity itself and contains also additional
information about the environment of the device. Figure 2
illustrates the sub-node structure of the "entity" section on the
left side.
The node "entity" accumulates the child nodes "network", "location",
"tadmin" and "fservice". The three nodes "location", "tadmin" and
"fservice" contain the additional node "address". The nodes "tadmin"
and "fservice" include additional the node "contact".
The node "entity" contains characterizing attributes of the entity.
The "entity" node is represented in the IDPEF DTD as:
Each entity node includes the individual attributes:
analyzer-ID
Exactly one string: Unique ID to identify the individual IDS-
entity (physical node).
domain
Exactly one string: Domain where the Analyzer belongs to.
name
Exactly one string: Name to identify the individual IDS-entity
(logical node).
version
Exactly one string: This attribute refers to the software version
of each IDS software entity. This is a read-only attribute and
will be set automatically by the IDS-entity itself. This value is
case-sensitive.
model
REQUIRED: The model attribute characterizes the Analyzer's soft-
and/or hardware.
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manufacturer
OPTIONAL: Manufacturer of the Analyzer's soft- and/or hardware.
Set by the Analyzer to identify the manufacturer for update
selection.
ostype
OPTIONAL: Operating systems type of the Analyzer. On POSIX 1003.1
compliant systems, is this the value returned in utsname.sysname
by the uname() system call, or the output of the "uname -s"
command. This is a read-only attribute and will be set
automatically by the IDS-entity itself to identify the os type for
update selections. This value is case-sensitive.
osversion
OPTIONAL: Operating systems version of the Analyzer. On POSIX
1003.1 compliant systems, is this the value returned in
utsname.release by the uname() system call, or the output of the
"uname -r" command. This is a read-only attribute and will be set
automatically by the IDS-entity itself to identify the current os
version for update selections. This value is case-sensitive.
serialnr
Exactly one string: Contains the serial number of the device for
replacement information purposes. This value is case-sensitive.
license
Exactly one string: Contains the license key/string. If no license
is used the value is "none". This value is case-sensitive.
expiration
Exactly one data string: Indicates the expiration date of the
license (date or "never"). The date format is yyyy/mm/dd.
time-zone
Exactly one time-string: Difference of local time to UTC.
(+/-00:00)
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ntp-server
Exactly one string: IP-addresses of the NTP servers in dotted
notation (IPv4 or IPv6) or server name. Multiple entries are
separated by comma (,).
dns-server
Exactly one string: IP-addresses of the DNS servers in dotted
notation (IPv4 or IPv6). Multiple entries are separated by comma
(,).
class
REQUIRED: This attribute specifies global, if this entity executes
active response or notify only.
focus
Exactly one value or more: Specification of the protected system.
Keywords are defined as: "network", "server", "application" and
"wireless". This is a read-only attribute and will be set
automatically by the IDS-entity itself.
certificate
OPTIONAL: String with the certificate that has to be used for the
next management access for the Manager. This value is case-
sensitive.
protect
OPTIONAL: This attribute will be used to provide additional
information about the protected systems and/or networks of this
IDS-entity for incident handling. It is a string with a free
description.
4.2.2.1. network
Network configuration parameters of the IDS management interface of
the entity will be summarized in this node. The network node is
represented in the IDPEF DTD as:
The individual attributes are brief described here:
IP-address
None or exactly one IP-address: IP-address of the IDS
communication interface in dotted IPv4 or IPv6 notation. This
interface is used for IDS communication only. For redundant
systems the collective IP-address will be set. If no exclusive IDS
management interface is in place, this attribute value MUST NOT be
set.
netmask
None or exactly one netmask: Netmask of the IDS communication
interface in dotted IPv4 or IPv6 notation corresponding to the
attribute IP-address of this node. This interface is used for IDS
communication only. If no exclusive IDS management interface is in
place, this attribute value MUST NOT be set.
gateway
None or exactly one IP-address: IP-address of the gateway for the
IDS communication in dotted IPv4 or IPv6 notation, corresponding
to the attribute IP-address of this node. This interface is used
for IDS communication only. If no exclusive IDS management
interface is in place, this attribute value MUST NOT be set.
ifspeed
None or exact one string: Settings for the interface like
interface speed, negotiations or duplex parameters. These
parameters will be set for the IDS communication interface only.
This value is case-sensitive. For redundant systems the value will
be set on all entities. If no exclusive IDS management interface
is in place, this attribute value MUST NOT be set.
port
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Exact one number: Port of the IDS management application (IDPEF
port for IDXP). The default port is 603 that is already defined
for IDXP by the IANA.
4.2.2.2. address
The node "address" contains information about the geographical
location. These are (location)name, street, building number, ZIP-
code and city. The address node is represented in the IDPEF DTD as:
It is RECOMMENDED to set all attributes of this node. Undefined
attributes will be accepted, but in case of problems with the entity
hardware, more time has be spend to locate the geographical address
of the physical device.
name
OPTIONAL, but SHOULD be set: Defines the company- or location-name
in which rooms the physical IDS entity is located. This value is
case-sensitive.
street
OPTIONAL, but SHOULD be set: Defines the street where the physical
IDS entity is located. This value is case-sensitive.
number
OPTIONAL, but SHOULD be set: Specifies the building number where
the physical IDS entity is located. This value is case-sensitive.
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ZIP
OPTIONAL, but SHOULD be set: Specifies the ZIP-Code where the
physical IDS entity is located. This value is case-sensitive.
city
OPTIONAL, but SHOULD be set: Specifies the city where the physical
IDS entity is located. This value is case-sensitive.
country
OPTIONAL, but SHOULD be set: Specifies the country where the
physical IDS entity is located. This value is case-sensitive.
4.2.2.3. location
The node "location" contains the child node "address" and enriches
this by the attributes "floor", "room", "rack" and "position" to
specify the location more in detail. In case of one logical but
physical redundant Analyzers with different postal addresses this
node will be used multiple times. The node "location" is represented
in the IDPEF DTD as:
floor
OPTIONAL, but SHOULD be set: Specifies the floor where the
physical IDS entity is located. This value is case-sensitive.
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room
OPTIONAL, but SHOULD be set: Specifies the room where the physical
IDS entity is located. This value is case-sensitive.
rack
OPTIONAL, but SHOULD be set: Specifies the rack where the physical
IDS entity is located. This value is case-sensitive.
position
OPTIONAL: Locates the hardware by an individual description. This
could be any hints or also longitude, latitude and altitude for an
open graphical position system. This value is case-sensitive.
4.2.2.4. contact
The node "contact" contains information to inform the corresponding
group or person. In "contact" are information about the
communication channel and the preferred communication channel. This
node is represented in the IDPEF DTD as:
mobile
OPTIONAL, but SHOULD be set: Provides the mobile phone number of
the contact.
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e-mail
OPTIONAL, but SHOULD be set: Provides the e-mail address of the
contact.
phone
OPTIONAL, but SHOULD be set: Provides the landline number of the
contact.
FAX
OPTIONAL, but SHOULD be set: Provides the FAX number of the
contact.
TTS
OPTIONAL, but SHOULD be set: Provides the assignment group of the
trouble ticket system for the contact. This value is case-
sensitive.
preferred
REQUIRED: Defines, which contact interface is preferred by the
contact. This attribute SHOULD be used, when more than one contact
information is defined.
4.2.2.5. fservice
The node "fservice" includes information about a local field service
to solve problems. This node uses the node "contact" with the
attribute "contactname" for additional contact information like name
of a person or the group name. This node is represented in the IDPEF
DTD as:
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contactname
REQUIRED: "contactname" is an open field to specify additional
information i.e. name of a contact person or the name of the field
service department. This value is case-sensitive.
4.2.2.6. tadmin
The node "tadmin" includes information about the technical
administrative (responsible) for this IDS entity. This node uses the
node "contact" with the attribute "contactname" for additional
contact information like name of a person or the group name. This
node is represented in the IDPEF DTD as:
contactname
REQUIRED: "contactname" is an open field to specify additional
information i.e. name of a main contact person or a team-name.
This value is case-sensitive.
4.2.3. The Update Section
The "update" section specifies all relevant information and data of
IDS entity updates. Therefore an unique ID, execution- and
reference-time have be set. Additional the update files, update
schedule and update notification are defined.
This node will be represented in the IDPEF DTD as:
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The update node has four attributes:
ID
REQUIRED: The "ID" is the unique identifier for the update. This
MUST be defined unique by the Manager or the Administrator. This
value is case-sensitive.
reference-time
OPTIONAL: The "reference-time" is the time of the Manager. Time
differences between the local IDS entity and the central IDS
Manager will be eliminated. By timely relative updates this
attribute is REQUIRED.
exec-time
REQUIRED: The "exec-time" terminates the time of execution start.
If no reference-time is specified, the exec-time refers to the
system time of the entity.
type
REQUIRED: Defines the kind of update. The value "update" is used
for patches, updates and upgrades. "backup" is used to collect all
important files for a parameter restore and the value "restore" is
used to restore a parameter configuration by the transferred
"update-file".
4.2.3.1. update-file
The "update-file" node specifies name and location of the update
files. Additional notifications for each update result will be
specified. This node uses the attribute "notification" to specify
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the result notification of each update file execution. This node
will be represented in the IDPEF DTD as:
The update node has six attributes:
filename
REQUIRED: This attribute contains the name of the file on the
local updated IDS entity. This value is case-sensitive.
location
REQUIRED: This attribute specifies the location of the update file
on the local updated IDS entity. This value is case-sensitive.
updateparameter
REQUIRED: This attribute contains the execution parameters. This
value is case-sensitive.
rank
OPTIONAL: Specifies the update-schedule by numeration.
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notification
OPTIONAL: "notification" refers to the attribute "response-ID" of
"react", which general notification channel has to be used for
notification. This value is case-sensitive.
ninfo
OPTIONAL: This attribute contains additional static information to
the IDS entity or the notification. This value is case-sensitive.
4.2.3.2. data
This node is REQUIRED and contains the (binary) update file in
base64 coded format. This value is case-sensitive.
4.2.4. The Alert Section
The "alert" section includes groups for parametrization of events
and reactions. The "alert" section is used to group and parameterize
single "event" and the "react" nodes for signalizations or
responses. The "alert" section structures all "event" and "react"
nodes by "group" nodes. The "alert" section will be represented in
the IDPEF DTD as:
4.2.4.1. group
The node "group" contains the parametrization nodes for events and
reactions. The "event" nodes are used to parameterize single events
and the "react" nodes contain general notification parameters for
signalizations or responses. The "group" node structures all "event"
and "react" nodes for a clustering of events and responses. The
"group" child node will be represented in the IDPEF DTD as:
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Each "event" node contains these 12 attributes:
enable
REQUIRED: The "enable" attribute defines if this alert is active
or not ("yes" or "no").
name
REQUIRED: This attribute defines the vendor-specific unique
identification for the event. This value is case-sensitive.
displayedas
REQUIRED: This value will be displayed in case of alarming/
notification. It should briefly characterize the occurred event.
This value is case-sensitive.
impact
OPTIONAL: This attribute specifies, which security value
(preferred: "confidence", "integrity", "availability" and/or
"none") would be affected primary by this attack.
severity
REQUIRED: The value of the attribute "severity" characterizes the
intrusion impact in context to other systems and/or applications.
The severity supports Operators to aggregate all severities of a
complex attack and several intrusions. This value is split in
"informational", "low", "medium", and "high" or a numeric rating
(e.g CVSS base value).
priority
OPTIONAL: The "priority" supports Operators to decide which
intrusion has to be observed and what will be primary reported for
statistical information like port-scans or sporadic connections
overload. In case of multiple detections of several simultaneous
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intrusions this value supports the Operator on which intrusion
should be the focus and in which order are the intrusions to
respond. This value covers a range from 1 to 255.
interface
OPTIONAL: The attribute "interface" defines the interface for the
alert parameters if possible/necessary. Multiple interfaces are
separated by a comma (,). This value is case-sensitive.
origin
OPTIONAL: Reference link to more information of this event:
unknown, vendor-specific, user-specific, bugtraqid, cve, osvdb,
etc. It could also include a link for more information about this
event. This value is case-sensitive.
frequency
OPTIONAL: Specifies the threshold within the measure interval, how
often the event has to be occur or a percentage value (threshold
or change), before the event will be raised.
interval
OPTIONAL: The "interval" attribute specifies the measure interval
in seconds for the value in "frequency", before the event will be
raised.
ignore
OPTIONAL: Defines an inactivity period of this event in seconds,
after it was raised. This prevents that a recurrent event floods
the alert panel.
ngroup
REQUIRED: This attribute will be used to map the notification for
this event.
4.2.4.1.1.1. connection
The "connection" node summarizes all parameters related to the
network connection. The node "connection" will be represented in the
IDPEF DTD as:
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Each "connection" node could contain these four attributes:
source
REQUIRED: This attribute defines initiating IP-addresses of the
connection. It will be used in dotted form with OPTIONAL "/" for
the netmask in dotted or bit-noted form. Multiple IP-addresses or
address ranges will be separated with a comma (,). IP-address
ranges could be specified by a hyphen (-) operator or netmask
after a slash (/) or wild card operator (*) like 192.168.*.10.
destination
REQUIRED: This attribute defines destination IP-addresses of the
connection. It will be used in dotted form with OPTIONAL "/" for
the netmask in dotted or bit-noted form. Multiple IP-addresses
will be separated with a comma. IP-address ranges could be
specified by a hyphen (-) operator or netmask after a slash (/) or
wild card operator (*) like 192.168.*.10.
port
REQUIRED: Defines the destination port or a port range for this
event. A port range will be specified by a hyphen operator (-).
Multiple ports or port ranges are separated by a comma (,).
direction
REQUIRED: This attribute defines if the connection parameters will
be analyzed in both directions ("bidirectional") or only in the
defined direction from source to destination ("unidirectional").
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4.2.4.1.1.2. system
The node "system" pools the attributes for system specific
parameters. The DTD representation for this node is:
type
REQUIRED: This attribute defines the type for the value, e.g. if
it is a directory or a file.
value
REQUIRED: This attribute defines the value of the attribute.
Multiple values are separated with a comma (,). This value is
case-sensitive.
enable
REQUIRED: The "enable" attribute defines if this alert is active
or not.
4.2.4.1.1.3. ipara
The "ipara" node provides individual parameter-extensions. It makes
it possible to set individual parameter names which are not
predefined. The "ipara" node provides the attributes "name", "value"
and "time". The DTD representation for this node is:
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This node could include these four attributes:
enable
REQUIRED: The "enable" attribute defines if this alert is active
or not.
name
REQUIRED: The attribute "name" defines the name of the individual
parameter for a correct assignment. This value is case-sensitive.
value
REQUIRED: The attribute "value" contains the individual parameters
of the individual attribute "name". This value is case-sensitive.
time
OPTIONAL: This attribute defines a time interval (i.e. 3600) in
seconds or a local time window (i.e. 10:00:00 - 23:00:00) for the
specified attribute. The time interval specifies an increase or
decrease of the attribute "value". If a time interval will be
defined the value of the attribute "value" is a fixed threshold.
4.2.4.1.2. react
The response and notification parametrization depends primary on the
feature set of the single IDS entity. All parameterized responses
and notifications MUST be checked before the local IDS entity
accepts the configuration. The "react" node will be represented in
the IDPEF DTD as:
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The "react" node could contain the five attributes:
enable
REQUIRED: The "enable" attribute defines if this alert is active
or not ("yes" or "no").
response-ID
REQUIRED: This attribute specifies the unique ID of the reaction
(response or notification).
type
REQUIRED: This attribute specifies the notification or response
type that will be taken by an identified attack. This could be to
block of this packet/connection by the Sensor or another device, a
redirect to a honey net, to take the sever offline, or an attack/
event signalization only.
structure
OPTIONAL: Some notification contents have an open structure. This
attribute defines the notification content. This value is case-
sensitive.
iaddress
REQUIRED: The attribute "iaddress" contains the IP-address (IPv4
or IPv6) of the notification receiving system or phone-number for
SMS notification.
5. Extending the IDPEF
IDS will be still developed in the future. Standardized protocols
MUST be the cutting edge to support research prototypes. Also IDPEF
has to support state of the art requirements of research projects.
To fulfill these requirements IDPEF will be extended by using the
individual parameter option "ipara". This technique is designed in a
way that adding new data will not require a change to the base IDPEF
schema and supports a lot of variants to extend the IDPEF.
If the extension with the "ipara" section does not provide needed
extension of IDPEF this section discusses how additional new data
elements that have no current representation in the data model could
be incorporated into the IDPEF. These techniques are designed in
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such a way that adding new data will not require a change to the
base IDPEF schema. This approach also supports extension of values
and attribute-names and an extension with specially marked
attributes and values is not necessary.
For example, an extended instance of the attributes of the event
class with the "ipara" option would look as follows:
6. Special Considerations
6.1. XML Validity and Well-Formed
Instead to include the DTD in the IDPEF compliant communication, it
will be defined in the header of the IDPEF-Message. Such IDPEF
documents will be well-formed and valid as defined in [5]. Other
IDPEF documents will be specified that a document header will be not
included (e.g. entries in an IDPEF-format configuration file). This
IDPEF documents are well-formed but not valid.
A document has a single element that contains everything else, and
that all other elements embedded nicely within each other without
any overlapping. Only in this case a document is valid and well-
formed.
A document is valid when it is well-formed, but it follows also
specific events (contained in the DTD) about which elements are
allowed in the document. A document could not be valid without a
DTD.
XML processors have to parse valid documents only. Without
validation, a document may contain elements in nonsense order and
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could not process correctly. A not valid document is not suited for
a proper parameter transfer. Therefore IDPEF documents MUST be
valid. Documents which are not valid abet misparametrizations and
will be not processed or applied.
6.2. Unrecognized XML Tags
In case that an IDPEF compliant application receives a well-formed
and valid IDPEF message containing tags that it does not understand,
this IDPEF message MUST continue to process, provided that such
messages meet the well-formatting requirement of section 6.1. It is
up to the individual application to decide how to process (or
ignore) any content from the unknown element(s). Unrecognized tags
MUST be notified and the new running parametrization of the entity
will be sent back as reply message. Within the replied IDPEF message
the error code has to be set with the error codes:
100: ok
200: Request or Update not valid
250: Request or Update not well-formed
300: Internal processing error by the XML
400: Activation of new parameters failed, restart with
old parametrization.
7. Security Considerations
IDPEF itself does not treat security matters directly. It is only an
exchange format to standardize and structure parametrization
information of IDS. The data encoded by the IDPEF might be
considered privacy sensitive information. Therefore care needs to be
taken in ensuring the appropriate disclosure during both document
exchange and subsequent processing entities.
IDPEF could be used local by the IDS software or in combination with
a transport protocol like IDXP [4] between Manager and Analyzers.
The exchange of the information MUST be handled by a transport
protocol, but the latter risk must be addressed by the systems that
process, store, and archive IDPEF data and information derived from
them.
The underlying messaging format and protocol used to exchange
instances of the IDPEF MUST provide appropriate guarantees of
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confidentiality, integrity, and authenticity. The use of a
standardized security protocol is encouraged. The security
considerations are provided by e.g. IDXP [4], TLS [10] and SASL
[12]. At least TLS 1.2 [11] and password authentication MUST be
used.
After the submission of IDPEF, care must be taken by the parser to
properly authenticate the recipient of the document and ascribe an
appropriate confidence to the data prior to action. Summarized
considerations are made here:
7.1. Privacy Considerations
Privacy is primary focused on information relating to an individual
or information which makes it possible to identify an individual.
Based on local law this could be defined very different. In this
context IP-addresses (of Analyzer and Manager as well as IP-
addresses for customizing the reference database) are not classified
as personnel information. The Administrator manages Analyzers of the
IDS over the Manager as intermediate with an individual user
interface.
The IDPEF standardizes the information exchange between Manager and
Analyzer. A trust relationship exists between these two
communication peers. The Manager controls the parametrization rights
of each individual (access control). The Manager entity acts as
intermediate between the Administrator and the Analyzer and provides
an individual user interface for the Administrator. A correct
identification and admission control of the individual Administrator
MUST be provided by the Manager. The authorization of the individual
Administrator on the manager entity is beyond the scope of IDPEF.
A correct processing of the information of IDPEF is part of the IDS
applications (Analyzer and Manager). Attributes and values that
could not be processed correctly MUST be signalized as described in
2.1. Parametrization Communication. Based on the parametrization
check the difference MUST be displayed to the Administrator. This
supports a check of the input (input control) to avoid
misparametrization of attributes and values.
The IDPEF is designed that the Manager holds no data permanently
about the parametrization of any Analyzer. Therefore the Manager has
to request the actual parametrization if needed. It is up to the
Analyzer application to store and protect the IDPEF information in a
safe environment and protects it against unattended access
(confidentiality) and modifications (integrity).
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It is assumed that the entities (Manager and Analyzer) are located
in a safe environment with a physical access control. The IDPEF is
created to parametrize IDS in a common structured way. To achieve
most interoperability all values are set in clear text. The IDPEF
information MUST be safely processed and stored (e.g. encrypted) by
the Analyzer application after receive. During the transport the
transport protocol MUST ensure appropriate confidence and integrity
for all IDPEF information. The logical access control has to be
handled also by the transport protocol to ensure that the Manager
will be authorized to set the transmitted parameters.
Analyzers provide requested information to any authorized Manager.
If there has to be set a transmission control, a proxy gateway
(intermediate handler) e.g. a Manager has to be set up at the border
to control the transmitted IDPEF parameters. The Manager (acting as
intermediate handler) checks and controls the transmitted
information to and from the peering Manager. The Manager (acting as
Administrator interface) MUST identify and control the input of the
individual Administrator (admission control).
IDPEF may contain personnel information (team names or names of
individuals, e-mail-addresses and/or telephone numbers) in the
entity section. It is not required but recommended to set these
attributes. It is up to the Administrator to decide if any of these
values is set or not. This information is intended to be used by the
Analyzer application for signalization of events or defects.
Therefore a subsequent transmission might be possible of this
personnel information. The Administrator should be aware who is able
to request the information and where the information will be
transmitted by the Analyzer. If these attributes are used, the
Administrator has to care that these values are not in conflict with
local law (on site of the Analyzer and the Manager as well as his
local site).
In any case the Analyzer application MUST grant confidence,
availability and integrity of received, processed, and stored IDPEF
information. Confidence and integrity of the IDPEF information
during the communication between Analyzer and Manager has to be
granted by the transport protocol. The subsequent sections are
focused on several security issues and its prevention during the
transport.
7.2. Systems Security Issues
The local usage of IDPEF data (i.e. stored in IDS configuration
files) MUST be protected at least against unauthorized usage,
inappropriate usage and/or Denial of Service. Confidentiality and
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integrity of local IDPEF configuration files MUST be handled in
responsibility of the particular IDS software. A peer entity
authentication within closed local software is RECOMMENDED. To
provide most flexibility the IDS software MUST choose which
mechanisms are adequate and has to ensure that its IDS configuration
files (IDPEF) is sufficient and state of the art protected.
The remote provisioning of IDPEF data MUST be protected against
unauthorized and inappropriate usage. All transmitted IDPEF
information has to be accepted from the Analyzers. The Manager has
to ensure, that only appropriate IDPEF data corresponding to the
authorization will be transmitted to the Analyzers. The Manager
authorizes as appropriate managing peer entity. So the Manager has
to check and enforce the authorization of its local users or
managing peer entities. The Manager will be authorized as
appropriate Manager based on SASL mechanisms.
7.3. Communications Security Issues
IDPEF itself provides no transport security and depends on the
security of the transport protocol. In case of transmission of IDPEF
between Manager and Analyzer the transport protocol e.g. IDXP [4]
MUST be guaranteed adequate data integrity, confidentiality and peer
entity authentication of the transferred message. The IDPEF use the
security features of the transport protocol IDXP [4].
The transport protocol has to provide separate mechanisms for
transport security, user authentication, and secure data exchange.
The transport protocol e.g. IDXP profile MUST offer the REQUIRED
security properties. At least TLS 1.2 [11] and SASL MUST be used to
provide transport security for IDPEF data. TLS supported cipher
suites provide varying levels of security. Administrators SHOULD use
the strongest cipher suite but SHOULD also carefully choose which
cipher suites are provisioned.
7.3.1. Passive Attacks
7.3.1.1. Confidentiality Violations (Eavesdropping)
Confidentiality violations such as eavesdropping are a serious
attack against IDPEF data. So the transport protocol IDXP [4] MUST
be used with the TLS and SASL profiles so that the communication is
adequate protected.
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7.3.1.2. Password Sniffing
IDPEF MAY also handle authentication information among others. Due
to the circumstances that IDPEF provides itself no transport
security confidentiality, integrity and peer entity authentication
MUST be provided by SASL and TLS profile option of IDXP. IDPEF MUST
NOT used without the TLS and SASL options of the transport protocol.
7.3.1.3. Offline Cryptographic Attacks
Offline cryptographic attacks are a serious risk to configuration
information. To hamper this kind of attacks Analyzer and Manager
SHOULD provide and use always state of the art algorithms. So the
Analyzer SHOULD refuse weak cryptographic algorithms for
confidentiality and/or authentication. IDXP has to be used with the
TLS 1.2 [11] and SASL option.
7.3.2. Active Attacks
7.3.2.1. Replay Attacks
To protect messages against replay IDPEF will be transmitted with
TLS [10] option of IDXP [4]. The appropriate level of security MUST
be chosen by the administrator carefully. To protect application
data refer to Appendix F2 of [10] for a discussion of security
considerations.
7.3.2.2. Message Insertion
To protect messages against insertions IDPEF will be transmitted
with TLS [10] option of IDXP [4]. The appropriate level of security
MUST be chosen by the administrator carefully. To protect
application data refer to Appendix F of [10] for a discussion of
security considerations.
7.3.2.3. Message Deletion
The communication proceeding of IDPEF ensures, that parameter
modification messages (classified as parameter-update) MUST send
back (classified as parameter-reply) so that the send Manager is
able to compare the send update message and the received update
response. Other deleted messages are uncritical and could be
requested a second time.
Transport layer of IDXP provides additional mechanisms to ensure a
correct message transport to the peer entity.
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7.3.2.4. Message Modification
To protect messages against modification IDPEF will be transmitted
with TLS [10] option of IDXP [4]. The appropriate level of security
MUST be chosen by the administrator carefully. To protect
application data refer to Appendix F2 of [10] for a discussion of
security considerations.
7.3.2.5. Man-In-The-Middle
IDPEF MUST be transported with TLS and SASL options of IDXP.
7.3.3. Topological Issues
Architectural solutions like firewalls and separated networks keep
the IDS communication in a WALLED GARDEN to make the communication
safer. This protects also against Denial of Service attacks.
7.3.4. Denial of Service
None of these security measures provide any real protection against
denial of service. Based on the transport layer security (SASL and
TLS 1.2) of the transport protocol e.g. IDXP [4], it is possible to
limit a variety of attacks on individual connections using forged
RSTs or other kinds of packet injection.
7.4. Digital Signatures
IDPEF assigns responsibility for integrity and authentication of the
message to the communications protocol IDXP [4], not the message
format. However, in situations where IDPEF messages are
parametrization part of a local configuration file, or in cases
where the digital signatures MUST be archived for later use, the
inclusion of digital signatures within an IDPEF message itself may
be desirable.
Specifications for the use of digital signatures [13] within IDPEF
messages are outside the scope of this document. However, if such
functionality is needed, use of the XML signature standard is
RECOMMENDED.
8. IANA Considerations
The IDMEF is registered by the IANA already. IDPEF will be used
local in closed environments primary. DTD reference links
preferential to the Manager of the IDS composite.
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For the IDPEF there will be no need to register the specifications
by the IANA [14]. The individual development and/or enhancement of
the DTD and their attribute values SHOULD offer more flexibility for
the use of the IDPEF and the DTD reference links to the Manager of
the IDS composite. The individual submission route of the RfC editor
accepts no IANA registrations and so no IANA registrations will be
aspired.
9. Conclusions
With IDPEF IDS are able to operate under one common independent IDS
Manager. As result, the IDS Manager was separated from the rest of
an IDS and could integrate Analyzers of different vendors and
analyzing levels.
Customizing of IDS could be due to a small amount of parameters and
values. Baseline configurations and references depend on the
internal processing and are not able to be standardized by a common
format.
With a single central administration entity it is possible to
operate, manage, maintain and administer a heterogeneous IDS
composite based on a small format. All connections are initialized
from the central Manager to the distributed Analyzer entities. All
updates (parameter and software) could be controlled, downloaded and
distributed to each single IDS entity from one central management
entity.
Connections from an IDS Analyzer entity to a system outside the
administrative IDS LAN are not necessary. The Manager still defines
the border of autonomous acted IDS but the environment is not longer
vendor-specific. The Manager is an independent system of IDS and
could be separated from the rest of the IDS. It is possible to
operate different IDS with one consistently administration front
end. This enables new and independent evolution streams for IDS
Analyzer as well as Manager.
10. Acknowledgments
A great inspiration was the IDMEF document [2] from Debar, Curry and
Feinstein and the IDXP document [4] from Feinstein and Metthews.
For writing this document [14] and [15] are very helpful for the
IANA section.
This document was prepared using 2-Word-v2.0.template.dot.
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APPENDIX A: Examples
This section shows different scenarios of IDPEF data exchange. For
all communication progressions at least one example will be
presented.
A.1. Feature-Requests
With a feature-request the current parameter setting will be
requested from an Analyzer. This section describes possible forms of
feature-requests of the Manager:
A.1.1. Global Feature-Request
A.1.2. Entity Feature-Request
A.1.3. Single Attribute Request
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A.1.4. Single Alert-Request (Port-Scan)
A.1.5. Multiple Alert Request
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A.1.6. Global Alert-Request
A.1.7. Multiple Global Alert-Request
A.1.8. Global Alert-Request to sensor with individual IDPEF Port
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A.2. Feature-Replies
The feature reply is the response of the contacted system with the
requested information. In this section the replies correspond with
the feature request of the section before.
A.2.1. Global Feature-Reply
This reply is based on the feature-set of two identifiable alerts by
this IDS-entity.
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frequency="20"
interval="900"
ngroup="DoS" >
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A.2.2. Version-Reply
version="10.3.x"
A.2.3. Single Alert Feature-Reply (Port-Scan)
frequency="20"
interval="60"
ngroup="portscan"
A.3. Entity Information Update
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A.4. Analyzer-Update
The Analyzer-update sets the values of the alert-attributes. This
will be described with an update by one and by two update-files.
A.4.1. Single Update
// binary Update file in base64 coded format
A.4.2. Multiple Updates and Notifications
// binary Update file in base64 coded format
// binary Update file in base64 coded format
A.4.3. Single Backup-Request
A.4.4. Single Backup-Reply
// binary restore file package in base64 coded format
A.4.5. Single Backup-Restore
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// binary restore file in base64 coded format
A.5. Alert Parametrization
Within this section the update of alert-parameter will be described
by update of the port scan alert and a multi-update including a
port-scan and a denial-of-service alert.
A.5.1. Single Parameter-Update (Port-Scan)
A.5.2. Multiple Parameter Update
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APPENDIX B: The IDPEF Document Type Definition (Normative)
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APPENDIX C: The IDPEF Schema Definition (Non-normative)
Intrusion Detection Parametrization Exchange Format
(IDPEF) Version 1.0
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default = "high"
default = "none"
default = "1"
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use="required"
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APPENDIX D: Change History
Changes from January 12, 2015 version to April 11, 2015 version:
o Typo-correction of "parameterization" to "parametrization".
o Add of "manufacturer", "ostype" and "osversion" attributes for
closer alignment with IDMEF and improved selection of Analyzer
criteria.
Changes from April 11, 2015 version to October 18, 2015 version:
o Several typo and grammar corrections.
o Correction of ToC misalignment.
o Drop out of BEEP usage (more common and open to transport
protocols)
o More precise to UFT-8 and UTF-16 usage in section 3.2.1
o Add Privacy Conditions
o Check to align with RfC5070-bis-14
o Update IANA Considerations (section8)
o Minor changes for better reading and understanding
Changes from October 18, 2015 version to November 21, 2015 version:
o Add informational reference RfC 6973 to list
o Move Privacy Considerations to Security Consideration's section
and rewrite privacy section
o Corrections of XML format in example Appendix.
Changes from November 21, 2015 version to February 28, 2016 version:
o Change back IANA Considerations (section8) that it fits to
individual submission route (No IANA actions)
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11. References
11.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[2] Debar H., Curry, D., and Feinstein, B., "Intrusion Detection
Message Exchange Format", RfC4765, 2007.
[3] Wood, M. and M. Erlinger, "Intrusion Detection Message
Exchange Requirements", RFC 4766, March 2007.
[4] Feinstein, B., Matthews, G., "The Intrusion Detection Exchange
Protocol (IDXP) ", RFC 4767, March 2007.
[5] Paoli, J., Sperberg-McQueen, C., Bray, T., and E. Maler,
"Extensible Markup Language (XML) 1.0 (Second Edition)", W3C
First Edition REC-xml-20001006, October 2000.
[6] Hollander, D., Bray, T., and A. Layman, "Namespaces in XML",
W3C REC REC-xml-names-19990114, January 1999.
[7] International Organization for Standardization, "Data elements
and interchange formats - Information interchange -
Representation of dates and times", ISO Standard 8601, Second
Edition, December 2000.
[8] Phillips, A. and Davis, M., "Matching of Language Tags", BCP
47, RFC 4647, September 2006.
[9] Hollenbeck, S., Rose, M., Masinter, L., "Guideline for the Use
of Extensible Markup Language (XML) within IETF Protocols",
BCP70, RfC 3470, January 2003
[10] Dierks, T., Rescorla, E., "The Transport Layer Security (TLS)
Protocol Version 1.2", RfC 5246, August 2008
[11] Sheffer, Y., Holz, R., P. Saint-Andre, P., "Recommendations
for Secure Use of Transport Layer Security (TLS) and Datagram
Transport Layer Security (DTLS) ", RfC 5725, May 2015
[12] Myers, J., "Simple Authentication and Security Layer (SASL)",
RfC 2222, October 1997
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11.2. Informative References
[13] Eastlake, D., Reagle, J., and D. Solo, "(Extensible Markup
Language) XML-Signature Syntax and Processing", RFC 3275,
March 2002.
[14] Freed, N. and J. Postel, "IANA Charset Registration
Procedures", BCP 19, RFC 2978, October 2000.
[15] Narten, T. and Alvestrand, H., "Guidelines for Writing an IANA
Considerations Section in RFCs", BCP 26, RFC 5226, May 2008.
[16] Cooper, A., Tschofenig, H., et al.,"Privacy Considerations for
Internet Protocols", RfC 6973, July 2013
Intellectual Property Statement
Copyright (c) 2015 IETF Trust and the persons identified as authors
of the code. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, is permitted pursuant to, and subject to the license
terms contained in, the Simplified BSD License set forth in Section
4.c of the IETF Trust's Legal Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info).
D.1.1. Author's Address
Bjoern-C. Boesch
Independent,
undisclosed
Germany
Email: bjoernboesch@gmx.net
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