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    <article-meta>
      <title-group>
        <article-title>Security Measurement Model for Large Scale Dynamic Systems *</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Syed Naqvi</string-name>
          <email>naqvi@enst.fr</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Michel Riguidel</string-name>
          <email>riguide@enst.fr</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Computer Science and Networks Department École Nationale Supérieure des Télécommunications 46 Rue Barrault</institution>
          ,
          <addr-line>75013 Paris</addr-line>
          ,
          <country country="FR">France</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>This article presents an overview of our proposed Security Management Model (SMM) for large scale dynamic systems. The goal of the SMM is to offer a simplified view of the overall system by taking into consideration the relevant data for the evaluation of the security assurance. A new thin infrastructure composed of the data/information relevant to the security evaluation of the system and services is proposed in SMM.</p>
      </abstract>
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  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>Traditionally, network administrators handle privileges,
exceptions, policies and other security settings; however,
today’s exponential growth of the mobile networks and
their dynamic interconnections have made it impossible for
the network administrators to manually handle all the
security functions. Moreover, the increasing complexity of
these heterogeneous networks has lead to a number of
security flaws. Any change or adjustment in a highly
dynamic context is prone to inconsistencies that result in
the serious security vulnerabilities. Hence it is desirable to
develop security assurance infrastructure that can monitor
and manage the overall state of security at any instant of
time. This security assurance infrastructure requires
interaction with the core security infrastructure, so that the
authorizations, exceptions, and security management as a
whole, can be achieved. The provision of such security
assurances is the prime objective of the BUGYO Project
[1].</p>
      <p>The rest of the paper is organized as: A brief description
of the project BUGYO is given in section 2. The Security
Management Model (SMM) is presented in section 3.
Some conclusions are drawn in section 4 with a note of our
future directions.
* This research is supported by the European Eureka-Celtic
Project BUGYO (Building Security Assurance in Open
Infrastructures) under reference number CP02-002</p>
    </sec>
    <sec id="sec-2">
      <title>2. The BUGYO Project</title>
      <p>The BUGYO project aims to define a security
framework to measure, document and maintain the security
assurance level of services based on telecommunications
system. The project intends to fill the current gap of a
general way to measure the confidence that operators and
end customers can have in the security of the
infrastructure, in end-to-end security services and in the
security of end-to-end services above those architectures.</p>
      <p>The main focus of the BUGYO project is to build a
framework providing integrated means to measure the
security assurances of a telecommunications infrastructure
and the overlay services in open infrastructures. The
project addresses security as a full system approach, and
the major expected result is a system security assurance
framework including methodologies, control metrics and
measures, best practices, tools and a certification cockpit.
The security cockpit represents the interface for the
operator or the service provider to perform necessary
operations in order to obtain and maintain a security
assurance level for a specified service.</p>
    </sec>
    <sec id="sec-3">
      <title>3. The Security Measurement Model (SMM)</title>
      <sec id="sec-3-1">
        <title>3.1. Overview</title>
        <p>
          The main idea behind the proposed modeling follows
the originally proposed Web model [
          <xref ref-type="bibr" rid="ref2">2</xref>
          ] for document
interlinking. If a subject s is a logical entity related to an
object of evaluation. s obtains a well-formatted document
ds that is established on demand by an appropriate agent bs.
These agents are designed to be able to gather security
assurance related information about s. The document ds is
specific to the particular requirements on s. In other words,
the different entities are not the same and possess different
document formats and agents. The security cockpit can be
used at any time to connect to one of the deployed bs to
visualize the network map and the deployment of the
updated implementation of any bi. Metaphorically, s can be
considered as a web-server serving a specific dynamically
generated webpage ds and is dynamically established by bs.
In this metaphor, the security cockpit appears as a
webbrowser and as an independent web-crawler.
        </p>
        <p>Our proposed model is a directed graph of security
assurance related documents starting with the object of
evaluation (typically a service) at the root. According to
this model, every logical, service-related entity s is
represented by its security assurance related document ds.
The edges of this graph are security evaluation related
dependencies, represented by arrows. The applied
semantics of an arrow leading from a document dA to a
document dB is “dA’s security assurance depends on dB’s
security assurance”. In other words, to evaluate the
security assurance of the entity A, one needs to consider
the security evaluation of an entity B.</p>
        <p>In a dynamic view, we need to represent data flows.
That is why every instantiation of the presented model is
required to provide a special format for data flows (i.e.
sessions, flows, exchanges, etc.) A data flow has a source
and a destination. It typically traverses various entities.
Thus, its security assurance evaluation typically depends
on several entities.</p>
        <p>The BUGYO project has considerable performance
constraints and, hence, it requires efficient mechanisms.
These constraints give birth to the idea of defining a new
infrastructure composed of the data/information relevant to
the security evaluation of the system and services. The
resulting simplified database will form a Security
Assurance Information Base (SAIB). A SAIB is a
collection of information that can be managed by the
cockpit and is relative to a subject or an object of the
system. The SAIB allow the cockpit to evaluate the
security assurance of this subject or object.</p>
        <p>A topological graph allows the cockpit to join the
different SAIB and to collect the information relative to the
security assurance of all the subjects and the objects. In
order to evaluate the overall security assurance of the
infrastructure the cockpit has to know the dependencies
between these subjects and objects. The cockpit evaluates
the overall security assurance of the system and the
management team is informed of the current assurance
level.</p>
      </sec>
      <sec id="sec-3-2">
        <title>3.3. Open Issues</title>
        <p>This work is still in progress and hence there are some
open issues that require further research considerations. A
list of some of these open and working issues is provided
in this section:</p>
      </sec>
      <sec id="sec-3-3">
        <title>Identification of the entities to be measured: Security</title>
        <p>assurance metrics are fundamental for the identification of
the entities to be measured or a set of measurable, direct
and indirect, security relevant and security enforcing
entities that can be mapped to specified security assurance
metrics.</p>
      </sec>
      <sec id="sec-3-4">
        <title>Determination of the granularity of the various entities:</title>
        <p>The sets of entities and relations constitute the system
model. They are the basis for the system security assurance
measurement. In some cases, the entities of a system are
complex themselves and, possibly, referred to as
subsystems, which in turn are divided into entities.</p>
      </sec>
      <sec id="sec-3-5">
        <title>Quantification of the security assurance with two</title>
        <p>proposed graphs: Methods aggregating the results for
individual system entities, possibly including other factors,
to system-wide security assurance values are needed.</p>
      </sec>
      <sec id="sec-3-6">
        <title>Semantically expressed assurance: Some mechanisms</title>
        <p>are needed to express semantically the assurances. It may
lead to the evolution of a Security Assurance Language.
Questions are: does SMM need a new language? Does
SMM require a descriptive or an executable language?</p>
      </sec>
      <sec id="sec-3-7">
        <title>How to guarantee the security of the cockpit: What</title>
        <p>about the Security Management Model if the cockpit itself
is attacked?</p>
      </sec>
      <sec id="sec-3-8">
        <title>Evaluation of the usability of the proposed model: This</title>
        <p>is one of the core issues of the project: how to use the
SMM to proceed to security assurance evaluation? Which
set of security related characteristics and entities have to be
considered? Which classification of basic model entities
has to be made? Which metrics will be used? Which
dependency and topological graph should be used?</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Conclusions and Future Directions</title>
      <p>Complexity of large scale dynamic systems is a major
obstacle to measure the security assurance. These systems
have to be modeled in such a way that security relevant
and security enforcing entities to be measured are captured.
The Security Management Model (SMM), briefed in this
paper, is an effort towards the adequate representation of
security assurance mechanism of such systems.</p>
      <p>This work is still in its nascent state with a number of
open issues. We foresee that in the coming months, a
refined SMM will be emerged with comprehensive
analytical validations. This stage will be followed by the
implementation of the model on a real test-bed.</p>
    </sec>
    <sec id="sec-5">
      <title>5. References</title>
    </sec>
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  <back>
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        <mixed-citation>
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            <given-names>The</given-names>
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          </string-name>
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  </back>
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