ETSI GS ISI 002 V1.2.1 (2015-11)

Information Security Indicators (ISI); Event Model A security event classification model and taxonomy

RGS/ISI-002ed2

General Information

• Status: Published
• Publication Date: 05-Nov-2015
• Technical Committee: ISI - Information Security Indicators
• Current Stage: 12 - Completion
• Due Date: 06-Nov-2015
• Completion Date: 06-Nov-2015

Standards Content (Sample)

GROUP SPECIFICATION
Information Security Indicators (ISI);
Event Model
A security event classification model and taxonomy

2 ETSI GS ISI 002 V1.2.1 (2015-11)

Reference
RGS/ISI-002ed2
Keywords
ICT, security
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3 ETSI GS ISI 002 V1.2.1 (2015-11)
Contents
Intellectual Property Rights . 6
Foreword . 6
Modal verbs terminology . 7
Introduction . 7
1 Scope . 9
2 References . 9
2.1 Normative references . 9
2.2 Informative references . 9
3 Definitions and abbreviations . 10
3.1 Definitions . 10
3.2 Abbreviations . 14
4 Positioning of the proposed event classification model . 16
4.1 Relationship with the ISO 27004 standard . 16
4.2 The critical importance of positioning the model appropriately . 16
4.3 The necessity for the model to rest on a detailed taxonomy . 18
4.4 Description of the taxonomy . 18
4.5 Complex security incidents versus basic security incidents . 20
4.6 The key drivers underlying the representation proposed . 21
4.7 The general description of the representation . 21
4.8 Link between the event model representation and the list of indicators (and related families) . 22
5 Comparison with other event classification models . 22
5.0 Introduction . 22
5.1 Risk analysis methods classifications . 23
5.2 CAPEC classification . 23
5.3 FIRST classifications . 23
6 Detailed description of the proposed representation of the different categories and sub-categories . 24
6.0 Introduction . 24
6.1 Intrusions and external attacks (Category IEX). 24
6.2 Malfunctions (Category IMF) . 26
6.3 Deviant internal behaviours (Category IDB) . 28
6.4 Behavioural vulnerabilities (Category VBH) . 30
6.5 Software vulnerabilities (Category VSW) . 32
6.6 Configuration vulnerabilities (Category VCF) . 33
6.7 General security (technical & organizational) vulnerabilities (Category VTC and Category VOR) . 33
7 Practical uses of the event classification model . 35
7.0 Introduction . 35
7.1 The classification model pivotal role. 35
7.2 The objective shared with operational risks . 36
7.3 The link with existing studies on cybercrime motivation (threat intelligence) . 37
7.4 The link with incident exchange . 40
7.5 Other uses of the classification model . 42
Annex A (informative): Overview of the ISO 27004 standard measurement model . 44
Annex B (informative): Field dictionary for the taxonomy . 45
B.0 Introduction . 45
B.1 Incidents . 45
B.1.1 Who and/or Why . 45
B.1.1.1 Accident . 45
B.1.1.2 Unwitting or unintentional act (error) . 45
B.1.1.3 Unawareness or carelessness or irresponsibility . 46
B.1.1.4 Malicious act . 46
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B.1.2 What . 47
B.1.2.1 Unauthorized access to a system and/or to information . 47
B.1.2.2 Unauthorized action on the information system and/or against the organization . 48
B.1.2.3 Installation of unauthorized software programs (malware) on a system (without the owner's consent) . 49
B.1.2.4 Information system remote disturbance . 49
B.1.2.5 Social engineering attacks . 49
B.1.2.6 Personal attack on organization's personnel or organization disturbance . 50
B.1.2.7 Physical intrusion or illicit action . 50
B.1.2.8 Illicit activity carried out on the public Internet (harming an organization) . 50
B.1.2.9 Various errors (administration, handling, programming, general use) . 51
B.1.2.10 Breakdown or malfunction . 52
B.1.2.11 Environmental events (unavailability caused by a natural disaster) . 52
B.1.3 How . 52
B.1.3.1 Unauthorized access to a system and/or to information . 52
B.1.3.2 Unauthorized action on the information system and/or against the organization . 53
B.1.3.3 Installation of unauthorized software programs (malware) on a system (without the owner's consent) . 54
B.1.3.4 Information system remote disturbance . 55
B.1.3.5 Social engineering attacks . 56
B.1.3.6 Personal attack on organization's personnel or organization disturbance . 56
B.1.3.7 Physical intrusion or illicit action . 56
B.1.3.8 Illicit activity carried out on the public Internet network (harming an organization) . 57
B.1.3.9 Various errors (administration, handling, programming, general use) . 57
B.1.3.10 Breakdown or malfunction . 57
B.1.3.11 Environmental events (unavailability caused by a natural disaster) . 57
B.1.4 Status . 57
B.1.4.1 Security event attempt (or occurrence) underway . 57
B.1.4.2 Succeeded (or performed) security event . 58
B.1.4.3 Failed security event . 58
B.1.5 With what vulnerability(ies) exploited (up to 3 combined kinds of vulnerabilities) . 58
B.1.5.1 Behavioural vulnerability . 58
B.1.5.2 Software vulnerability. 58
B.1.5.3 Configuration vulnerability . 58
B.1.5.4 General security vulnerability . 58
B.1.5.5 Conception vulnerability . 58
B.1.5.6 Material vulnerability . 58
B.1.6 On what kind of asset . 58
B.1.6.1 Data bases and applications . 58
B.1.6.2 Systems . 59
B.1.6.3 Networks and telecommunications . 61
B.1.6.4 Offline storage devices . 62
B.1.6.5 End-user devices . 62
B.1.6.6 People . 63
B.1.6.7 Facilities and environment . 63
B.1.7 With what CIA consequences . 64
B.1.7.1 Loss of confidentiality (with types of loss and with the amount of data as a possible complement) . 64
B.1.7.2 Loss of integrity (with types of loss) . 65
B.1.7.3 Loss of availability (with types of loss and with the duration as a possible complement) . 65
B.1.8 With what kind of impact . 66
B.1.8.1 Direct impact . 66
B.1.8.2 Indirect impact . 66
B.2 Vulnerabilities . 66
B.2.1 What . 66
B.2.1.1 Behavioural vulnerabilities . 66
B.2.1.2 Software vulnerabilities . 69
B.2.1.3 Configuration vulnerabilities . 69
B.2.1.4 General security (organizational) vulnerabilities . 70
B.2.1.5 Conception vulnerability . 72
B.2.1.6 Material vulnerability . 72
B.2.2 On what kind of assets . 73
B.2.3 Who (only for behavioural vulnerabilities) . 73
B.2.4 For what purpose (only for behavioural vulnerabilities) . 73
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5 ETSI GS ISI 002 V1.2.1 (2015-11)
B.2.5 To what kind of possible exploitation . 74
Annex C (informative): Authors & contributors . 75
Annex D (informative): Bibliography . 76
History . 78

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6 ETSI GS ISI 002 V1.2.1 (2015-11)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://ipr.etsi.org).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Group Specification (GS) has been produced by ETSI Industry Specification Group (ISG) Information Security
Indicators (ISI).
The present document is included in a series of 6 ISI specifications. These 6 specifications are the following (see
figure 1 summarizing the various concepts involved in event detection and interactions between all parts):
• ETSI GS ISI 001-1 [i.3] addressing (together with its associated guide ETSI GS ISI 001-2 [i.4]) information
security indicators, meant to measure application and effectiveness of preventative measures.
• The present document (ETSI GS ISI 002) addressing the underlying event classification model and the
associated taxonomy.
• ETSI GS ISI 003 [i.11] addressing the key issue of assessing an organization's maturity level regarding overall
event detection (technology/process/ people) in order to evaluate event detection results.
• ETSI GS ISI 004 [i.12] addressing demonstration through examples how to produce indicators and how to
detect the related events with various means and methods (with a classification of the main categories of use
cases/symptoms).
• ETSI GS ISI 005 [i.13] addressing ways to produce security events and to test the effectiveness of existing
detection means within organizations (for major types of events), which is a more detailed and a more case by
case approach than in ETSI GS ISI 003 [i.11] and which can therefore complement it.
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GS ISG ISI Series Summary Definition
Event
reaction
measures
Fake events
(Simulation)
Security Event
Real Detected
prevention detection
events events
measures
measures
Residual risk
(event model-
centric vision)
Figure 1: Positioning the 5 GS ISI against the 3 main security measures
Modal verbs terminology
In the present document "shall", "shall not", "should", "should not", "may", "need not", "will", "will not", "can" and
"cannot" are to be interpreted as described in clause 3.2 of the ETSI Drafting Rules (Verbal forms for the expression of
provisions).
"must" and "must not" are NOT allowed in ETSI deliverables except when used in direct citation.
Introduction
A corporate Cyber Defence and SIEM approach implements continuously security improvements with the main goals
to:
• operationally and constantly reduce the residual risk incurred by their Information Systems (see figure 2,
which highlights the two associated types of events - incidents and vulnerabilities - and the joint area covered
by IT security policy through the concept of usage or implementation drift); and
• to assess the actual application and real effectiveness of their security policies (or of their ISMS, if they have
one), for the purpose of their constant improvement.
Such an approach, which to a large extent relies on using the traces available in the Information System's various
components, is organized around an "event-model centric" vision, and can also be tied up to the PDCA model that is
commonly used in quality and security areas. As such, this primarily involves implementing this model's PDCA
"Check" step on the basis of very detailed knowledge of threats and vulnerabilities.
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8 ETSI GS ISI 002 V1.2.1 (2015-11)
The 3 kinds of residual risk
Area covered by
IT Security policy
Known Known
Unknown
Actually
residual residual
residual
covered
risk
risk
risk
risk
(accepted)
(suffered)
Incidents exploi-
Incidents exploiting Incidents not
ting unknown
known but uncovered possible
Incidents exploiting
vulnerabilities
or not tackled vulne- (vulnerabilities
known vulnerabilities
rabilities due to usage remediated by
or implementation drift operational or
not practices)
Figure 2: The 3 kinds of residual risks
Worldwide trends in ICT security show that significant progress can be accomplished within a few years with the
deployment of an organization-wide operational Cyber Defence and SIEM approach. A recent survey by a major
consulting firm of 15 major companies and organizations brings to light nine key success criteria. The two most
important criteria are:
• The reliance of the Cyber Defence and SIEM approach on a security event classification model that takes into
account both incidents and vulnerabilities, and that stresses particular attention to malicious and intentional
acts, the monitored events themselves being selected on the basis of main relevant CIA risks and associated
metrics (e.g. statistics).
• Training with this model for the relevant people using the Information System, with particular attention to the
presentation of concrete examples of disasters associated with inventoried security event main types.
As such, the present document's objective is to build a full taxonomy to thoroughly describe all IT security events (and
when appropriate and necessary non-IT security events) and, based on this, to present an original representation that
leverages the current international best practices and enables diversified and complex uses. The choice of a detailed
taxonomy, which describes security events through a set of attributes (different for incidents and vulnerabilities),
ensures that all possible situations can be taken into account with the required flexibility (especially thanks to the
provided open dictionary), while the representation chosen for the taxonomy, highlighting the main categories generally
accepted by industry consensus, makes the event classification model easier to understand and embrace for
stakeholders. ®
The present document is based on work carried out by the Club R2GS , a French association created in 2008,
specializing in Cyber Defence and Security Information and Event Management (SIEM), gathering large French
companies and organizations (mainly users). The present document (ETSI GS ISI 002), as well as the other GS of ISG
ISI, are therefore based on a strong experience, this community of users having adopted and used the event
classification model and the related reference framework for indicators for more than three years on a national and
world-wide scale.
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1 Scope
The present document provides a comprehensive security event classification model and associated taxonomy (based on
existing results and hands-on user experience), covering both security incidents and vulnerabilities. The two latter ones
become nonconformities when they violate an organization's security policy. The present document mainly supports
operational security staff in their effort to qualify and categorize detected security events, and more generally all
stakeholders (especially CISOs and IT security managers) in their needs to establish a common language.
2 References
2.1 Normative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are necessary for the application of the present document.
Not applicable.
2.2 Informative references
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific. For specific references, only the cited version applies. For non-specific references, the latest version of the
reference document (including any amendments) applies.
NOTE: While any hyperlinks included in this clause were valid at the time of publication, ETSI cannot guarantee
their long term validity.
The following referenced documents are not necessary for the application of the present document but they assist the
user with regard to a particular subject area.
[i.1] NIST SP 800-126 Revision 2 (September 2011): "The Technical Specification for the Security
Content Automation Protocol (SCAP): SCAP Version 1.2".
[i.2] MITRE CCE List Version 5.20120314 (March 2012): "Common Configuration Enumeration".
[i.3] ETSI GS ISI 001-1: "Information Security Indicators (ISI); Indicators (INC); Part 1: A full set of
operational indicators for organizations to use to benchmark their security posture".
[i.4] ETSI GS ISI 001-2: "Information Security Indicators (ISI); Indicators (INC); Part 2: Guide to
select operational indicators based on the full set given in part 1".
[i.5] ISO/IEC 27000:2012: "Information technology -- Security techniques -- Information security
management systems -- Overview and vocabulary".
[i.6] draft-ietf-mile-rfc5070-bis-11: "The Incident Object Description Exchange Format v2".
[i.7] ISO 27002:2013: "Information technology -- Security techniques -- Code of practice for
information security management".
[i.8] ISO 27004:2009: "Information technology -- Security techniques -- Information security
management -- Measurement".
[i.9] ISO 27005:2011: "Information technology -- Security techniques -- Information security risk
management".
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10 ETSI GS ISI 002 V1.2.1 (2015-11)
[i.10] FIRST Classification (November 2004): "CSIRT Case Classification (Example for enterprise
CSIRT)".
[i.11] ETSI GS ISI 003: "Information Security Indicators (ISI); Key Performance Security Indicators
(KPSI) to evaluate the maturity of security event detection".
[i.12] ETSI GS ISI 004: "Information Security Indicators (ISI); Guidelines for event detection
implementation".
[i.13] ETSI GS ISI 005: "Information Security Indicators (ISI); Guidelines for security event detection
testing and assessment of detection effectiveness".
3 Definitions and abbreviations
3.1 Definitions
For the purposes of the present document, the following terms and definitions apply (ISO/IEC 27000 [i.5] compliant
where applicable):
NOTE: See also the summary chart at the end of this list.
asset: information asset that has value to the organization and that can be broken down in primary assets (such as
business activities, data, application software, etc. which hold the business value) and secondary/supporting assets
(network or system infrastructure, which host primary assets)
assurance: refers to the planned and systematic activities implemented in a management system so that management
requirements for a service will be fulfilled
NOTE: It is the systematic measurement, comparison with a standard, monitoring of processes and an associated
feedback loop that confers error prevention. This can be contrasted with Management "Control", which is
focused on process outputs.
base measure: regarding the "indicator" issue, a base measure is defined in terms of an attribute and the specified
measurement method for quantifying it (e.g. number of trained personnel, number of sites, cumulative cost to date)
NOTE: As data is collected, a value is assigned to a base measure.
continuous auditing: periodic verification and collection of a series of controls identified within the Information
System, corresponding with the detection of incidents and of software, configuration, behavioural or global security
framework vulnerabilities and/or non-conformities
NOTE: There are three checking levels (in principle, hierarchy notably implemented within banking and financial
institutions):
Detailed behavioural, global security framework or technical checking at the security software or
equipment level (network, system, application software).
Level 1 checking via monitoring of trends and deviations of a series of significant measurement
points.
Level 2 checking (verification of existence of a satisfactory assurance and coverage level of the
chosen control and measurement points, and of implementation of regulatory requirements).
Continuous auditing can be either manual or automatic (for example, monitoring by means of tools
appropriate for a SIEM approach). Finally, continuous auditing is generally associated with statistical
indicators (levels of application and effectiveness of security controls), that provide information
regarding the coverage and assurance level of the security controls in question.
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criticality level (of a security event): level defined according to the criteria which measures its potential impact
(financial or legal) on the company assets and information, and which make it possible to evaluate the appropriate level
of reaction to the event (incident treatment or vulnerability or nonconformity removal)
NOTE: The criticality level of a given event is determined by the combination of its severity level (inherent to the
event itself - see definition below) and of the sensitiveness of the target attacked or concerned (linked to
the asset estimated value for the company - whose value concerns confidentiality, integrity or
availability). This concept of criticality level (usually defined on a scale of four levels) is at the core of
any SIEM approach, for which classifying security events processing according to organization-defined
priorities is vital from both a security and economic point of view.
derived measure: regarding the "indicator" issue, a measure that is derived as a function of two or more base measures
effectiveness (of security policy or of ISMS): as a supplement to the actual application of security policy (or of ISMS)
and of its measures assessment, it is necessary to assess its level of effectiveness, that can be estimated through
identified residual risk (that corresponds with the residual vulnerabilities that are actually exploited and that have led to
security incidents)
NOTE: It should be added that the term "efficiency" is sometimes also used, but generally with a different
meaning of economy in the use of resources (not addressed here for reasons of lesser relevancy).
(security) incident: single unwanted or unexpected security event, or series thereof, that correspond to the exploitation
of an existing vulnerability (or attempt to), and with an actual or potential threat (attempt underway), that have a
significant probability of compromising business operations and threatening information security
NOTE: In case of success, an incident affects nominal operations of all or part of an information system
(according to the Confidentiality, Integrity and Availability criteria - English acronym CIA). An incident
that manifests itself through previously unseen phenomena, or is built as a complex combination of
elementary incidents often cannot be qualified and therefore inventoried or categorized easily; such an
incident will often be referred to as an anomaly.
indicator: measure that provides an estimate or evaluation of specified attributes derived from an analytical model with
respect to a defined information need
NOTE: Indicators are the basis for analysis and decision making.
log: continuous recording of software usage computer data, with specific characteristics: detailed and specified
structure, time-stamping, recording as soon as they occurs in files or other media
NOTE: Logs are a kind of trace (more general concept - see definition below).
non-conformity: security event that indicates that organization's required security rules and regulations have not been
properly enforced, and are therefore the consequence of a usage or implementation drift
NOTE: Continuous monitoring of non-conformities (similar to continuous auditing - Cf. this term above) enables
to better ensure that an organization's security policy is being enforced. Non-conformity can be further
refined according to their kind: configuration, behaviour, global security (technical and organizational)
and material. Non-conformities are also vulnerabilities or incidents, depending on the situation (see
definition).
periodic audit (Periodic scanning): using isolated audit means, periodic acquisition and verification of security
controls
NOTE: A periodic audit can also be either manual or automatic (for example, carried out through scanner type
tools). Finally, a periodic audit is generally Boolean (all or nothing compliance level).
risk: product of the probability of occurrence of a security incident involving a specific asset by its impact on this asset
(impact assessed according to the CIA sensitivity level)
NOTE: The level of risk exposure (concept which is used in risk assessment methods) corresponds to the product
of the vulnerability level of the asset in question by the threat level hanging over it.
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12 ETSI GS ISI 002 V1.2.1 (2015-11)
risk not covered (by existing security measures): Risk sometimes also referred to as "residual", which breaks down
into 3 shares:
• Known and realized suffered risk, corresponding to the impact suffered by the organization under attack when
the security policy is not applied (configuration, behavioural or global security non-conformities), and when
known and critical software vulnerabilities are not appropriately addressed.
• Known and accepted risk that corresponds to a risk taken by choice by an organization, by comparing the risk
associated with attacks with economic, usage and security level considerations.
• Unknown risk associated with unknown and unpatched vulnerabilities, or innovative attack vectors.
security event: information about a change of state in a system that may be security relevant and that indicates the
appearance of a risk for the organization
NOTE: A security event is either an incident or a vulnerability occurrence or detection (see definition of these
terms). 500 security events have been inventoried within the industry, and are grouped into 9 different
major categories, with the 3 first corresponding to incidents, and the 4 last to vulnerabilities: external
attacks and intrusions, malfunctions, internal deviant behaviours, behavioural vulnerabilities, software
vulnerabilities, configuration vulnerabilities, general security (technical or organizational) vulnerabilities.
severity level (of security incident): Level (generally defined on a 4-element scale) inherent to the event itself and that
depends on several criteria that vary according to the types of events (in decreasing order of importance):
• Dangerousness is the result of multiple factors with variable combinations according to circumstances or types
of incidents: propagation speed for a worm, virulence, effectiveness, importance and number of impacted
assets, capability of harm, target reachability, capability of remote action, persistence, weakness or lack of
curative means, and extend of compromise (depth of component which is can be or has been reached, concept
of Defence in Depth or DiD).
• Stealthiness covers the level to which the incident can be hidden to the defender: obvious visibility, visible
through simple and easy to use mechanisms, detection requires advanced technical tools, almost invisibility. It
is a key factor for monitoring and detection. Anonymization and camouflage, or active and passive masking
techniques are stealthiness techniques. Stealthiness takes on an indirect meaning when it applies to similar not
yet detected incidents.
• Feasibility relates to the attacker's motivation and skills. It increases proportionally to all the necessary
prerequisites (regarding skills, tools, financial means, collusion, initial access, etc.) combined with the
presence of exploitable vulnerabilities; feasibility can be tied often to the frequency of attacks that can be
detected in the world. Its assessment is not simple, because it is subject to change. For example, it may be
difficult to create a hacking tool for a given vulnerability. However, once the tool is released on the Internet, it
can be used by unskilled attackers. Feasibility takes on an indirect meaning when it applies to a potential threat
(see definition of this term), as the analysis of its factors required to evaluate it provides an interesting
evaluation of the risk.
NOTE: This notion appeared in the mid-1990s within the framework of the ITSEC certification, then towards the
end of this decade with the issue of global and public management of vulnerabilities and "malware"
(security software vendors and CERTs). It is once again being developed at the present time with the
recent release of log analysis and correlation tools that completely integrate this concept along with
criticality.
severity level (of vulnerability or of nonconformity): The severity level definition is about the same as the one for
incidents, with a few small differences:
• Dangerousness: impact of the related attacks, weakness of protective techniques, possible remote exploitation,
scope of the target / victim population (number of machines, of services, …), importance to organization of the
security rule that was violated.
• Stealthiness: same definition as for incident.
• Exploitability (by attackers), is the opposite definition of incident feasibility.
NOTE: The proposed definition is in line with the CVSS (NIST 800-126 [i.1] or SCAP) standard for software
vulnerabilities.
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13 ETSI GS ISI 002 V1.2.1 (2015-11)
security policy: overall intention and requirements as formally expressed by management
NOTE: Two levels are used: general statement and detailed rules. Rules apply to network and systems
configuration, user interaction with systems and applications, and detailed processes and procedures
(governance, operational teams, and audit). Violation of a rule brings about nonconformity, which is
either an incident or vulnerability.
sensitivity level: level which corresponds to the potential impact (financial, legal or brand image) of a security event on
an asset, an impact linked to the estimated value of the asset for the company along four possible viewpoints: its
Confidentiality, Integrity and Availability (CIA) and sometimes its accountability
SIEM (Security Information and Event Management): SIEM solutions are a combination of the formerly disparate
product categories of SIM (security information management) and SEM (security event management). SEM deals with
real-time monitoring, correlation of events, notifications and console views. SIM provides long-term storage, analysis
and reporting of log data
NOTE: The present document extends these two notions under the generic SIEM acronym, which encompasses
all organizational, processes and human aspects necessary to deploy and operate these tools, and which
include vulnerability and nonconformity management; it should be referred to Cyber Defence approaches
in the most complex case.
taxonomy: science of identifying and naming species, and arranging them into a classification
NOTE: The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description
and use of taxonomic units, known as taxa (singular taxon). A resulting taxonomy is a particular
classification ("the taxonomy of ."), arranged in a hierarchical structure or classifi
...