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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Security Analysis Models for Multimedia Information Resources in Social Networks</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Stanislav Milevskyi</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Volodymyr Aleksiyev</string-name>
          <email>aleksiyev@gmail.com</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Olha Korol</string-name>
          <email>korol.olha2016@gmail.com</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Oleksandr Milov</string-name>
          <email>oleksandr.milov@hneu.net</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Serhii Yevseiev</string-name>
          <email>serhii.yevseiev@hneu.net</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Simon Kuznets Kharkiv National University of Economics</institution>
          ,
          <addr-line>9a Nauki ave., Kharkiv, 61166</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
      </contrib-group>
      <fpage>60</fpage>
      <lpage>67</lpage>
      <abstract>
        <p>The paper presents a description of classical and modern multimedia information resources security threats in social networks. It also provides an overview of methods and models for analyzing social networks. Proposed an approach to the creation of a methodology for building security systems for the exchange of multimedia content in social networks through the development of conceptual foundations, methods, and technologies for detecting, assessing, and countering information security threats.</p>
      </abstract>
      <kwd-group>
        <kwd>1 Cybersecurity</kwd>
        <kwd>social networks</kwd>
        <kwd>multimedia content</kwd>
        <kwd>security threats</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>The continuous development of global communication services has turned social networks into the
dominant segment of information exchange and citizen communication in the virtual space.</p>
      <p>
        The availability of personal media for generating multimedia content and online communities for
sharing it has led to explosive growth in the volume of multimedia information that circulates in
social networks. In contrast to textual information, for the processing of which there are a wide
number of tools and methods [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ], for the processing of multimedia content, a wide range of available
tools and methods are not observed. Simultaneously with the increase in the volume of multimedia
content in social networks, the number, and variety of negative impacts carried out on information
resources of a multimedia type or with their help are increasing. Such actions are a source of threats to
information security [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ].
      </p>
      <p>The growth in the number of users of social networks and multimedia services is currently so
active that it outstrips the increase in the world’s population. In Fig. 1, it can be seen that the growth
rates of the number of users of Facebook and YouTube are significantly higher than the rate of
population growth (151.87 and 111.64 compared to 83.873). The increase in information security
threats in social networks is directly related to the emergence of such an effect. This can be explained
both by an increase in the number and complexity of the content structure and by a significant
increase in the number of inexperienced (unprepared, new) users.</p>
      <sec id="sec-1-1">
        <title>Facebook users</title>
      </sec>
      <sec id="sec-1-2">
        <title>Youtube users</title>
      </sec>
      <sec id="sec-1-3">
        <title>World population</title>
      </sec>
    </sec>
    <sec id="sec-2">
      <title>2. Problem Review</title>
      <p>
        Information security threats are of a different nature and can be implemented using special
software or technologies that are inaccessible to the vast majority of users of social networks due to
their lack of appropriate professional competence [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ] (Fig. 2).
      </p>
      <p>Information security threats in social networks
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      <p>Informational and psychological impact on group users by imitating the mass discussion of any
information (the so-called astroturfing). This type of threat has a negative impact on the joint work of
the group members, reflecting on the consciousness of the participants in the discussion.</p>
      <p>Manipulation with information (information overload, misinformation, distortion of information,
or mixing true facts with false ones). This threat is capable of affecting the mind and consciousness of
the group members, as well as inciting them to carry out destructive and socially dangerous actions.</p>
      <p>Posting materials in the social network community without the consent of the copyright holder.
The ease of infringement of copyright in community-posted student work leads to unauthorized
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copying and use of fragments of the work.</p>
      <p>Reproduction, duplication, or distribution of objectionable material intentionally posted by group
members.</p>
      <p>Cyber humiliation and cyberbullying of network members. Humiliation and insult in community
discussions destroy the moral and psychological atmosphere and hinders the implementation of
activities.</p>
      <p>
        In [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ], a specific list of information security threats arising in social networks was highlighted.
These threats include spam on social networks, social engineering threats, posting honeypots on social
networks, impersonating friends, the possibility of replacing a person or a masquerade, stealing
passwords and phishing, using URL shortening services, using the same usernames and passwords in
corporate networks and external social resources, web attack, information leakage, and compromise
of the behavior of company employees, APT (Advanced Persistent Threat) attack.
      </p>
    </sec>
    <sec id="sec-3">
      <title>3. Research Materials</title>
      <p>To effectively reduce the degree of influence of threats to information security in social networks,
it is necessary to adequately apply methods of analysis of social networks, which make it possible to
identify potential “centers of influence” capable of forming a collective public opinion for destructive
purposes.</p>
      <p>
        Currently, in the analysis of social networks, there are four main areas of research [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ]: structural,
resource, normative and dynamic (Fig. 2).
      </p>
      <sec id="sec-3-1">
        <title>Trends in the analysis of social networks</title>
      </sec>
      <sec id="sec-3-2">
        <title>Structural</title>
      </sec>
      <sec id="sec-3-3">
        <title>Approach</title>
        <p>link
analysis</p>
        <p>Structural and
behavior</p>
        <sec id="sec-3-3-1">
          <title>Statistical</title>
          <p>analysis of social
networks</p>
          <p>Definition of
communities on
social network</p>
        </sec>
        <sec id="sec-3-3-2">
          <title>Analysis of network multimedia information</title>
        </sec>
      </sec>
      <sec id="sec-3-4">
        <title>Resource approach</title>
        <sec id="sec-3-4-1">
          <title>Social media content analysis</title>
        </sec>
        <sec id="sec-3-4-2">
          <title>Analysis of text information in social networks</title>
        </sec>
        <sec id="sec-3-4-3">
          <title>Integration of data from sensors and social networks</title>
        </sec>
        <sec id="sec-3-4-4">
          <title>Arrangement of tags</title>
        </sec>
      </sec>
      <sec id="sec-3-5">
        <title>Normative approach</title>
        <sec id="sec-3-5-1">
          <title>Social analysis</title>
        </sec>
        <sec id="sec-3-5-2">
          <title>Social privacy impact media</title>
        </sec>
        <sec id="sec-3-5-3">
          <title>Discovering experts networks on</title>
        </sec>
        <sec id="sec-3-5-4">
          <title>Random walk</title>
        </sec>
      </sec>
      <sec id="sec-3-6">
        <title>Dynamic approach</title>
        <sec id="sec-3-6-1">
          <title>Evolution in dynamic social networks</title>
        </sec>
        <sec id="sec-3-6-2">
          <title>Forecast of connections forming in social networks</title>
        </sec>
        <sec id="sec-3-6-3">
          <title>Social media visualization</title>
        </sec>
        <sec id="sec-3-6-4">
          <title>Vertex classification</title>
          <p>In the structural approach, all network participants are considered as nodes of the graph, which
affects the configuration of edges and other network participants. The main attention is paid to the
geometric shape of the network and the intensity of interactions (the weight of the edges); therefore,
such characteristics as the mutual arrangement of vertices, centrality, and transitivity of interactions
are investigated. Structural and network exchange theories are used to interpret the results in this
direction.</p>
          <p>The resource-based approach considers the possibilities of participants to attract individual and
network resources to achieve certain goals and differentiates participants who are in identical
structural positions of the social network by their resources. Knowledge, prestige, wealth, race, gender
can act as individual resources. Network resources are understood as an influence, status, information,
capital.</p>
          <p>The normative approach examines the level of trust between participants, as well as the norms,
rules, and sanctions that affect the behavior of participants in a social network and the processes of
their interactions. In this case, the social roles that are associated with this edge of the network are
analyzed, for example, the relationship between the manager and the subordinate, friendship, or
family ties. The combination of individual and network resources of a participant with the norms and
rules in force in this  social  network  forms  his  “network capital.” In a simplified form, “network
capital” can be viewed as the sum of some advantages that a participant can receive at an arbitrary
point in time to achieve a certain goal.</p>
          <p>A dynamic approach is a direction in the study of social networks, in which the objects of research
are changing in the network structure over time: for what reasons do the edges of the network
disappear and appear, how does the network change its structure under external influences, are there
any stationary configurations of the social network.</p>
          <p>As can be seen from previous, when analyzing social networks, a fairly wide range of problems is
solved and methods from various fields of knowledge are applied. However, to directly identify the
characteristics and properties of social networks and their segments in order to identify potential
sources of threats to information security, it is necessary to consider specific models for analyzing
social networks (Table 1).</p>
          <p>Content and characteristics of the model
For many social tasks, such as finding a job, weak ties are much more
effective than strong ties (ant colony optimization approach)
The hypothesis is that each person is familiar with any other
inhabitant of the planet through a chain of mutual acquaintances, on
average, consisting of six people. So far, this claim has not been
refuted. On the contrary, as proof of the correctness of the
hypothesis, the observation is put forward that the diameter of most
networks is relatively small.</p>
          <p>Any social network can be mathematically represented as a graph
(stochastic block models, probabilistic graph models, conventional
graph models)
To determine the relative importance (weight) of the graph vertices
(that is, how influential a participant is within a particular network),
the concept of centrality is introduced—a measure of proximity to
the center of the graph.</p>
          <p>Designed to separate informative web pages from spam. TrustRank is
a value that gives an estimate of whether a particular site can be
trusted, assuming that it does not contain spam. The more links
there are on the site, the less trust is “passed” through each such
link. TrustRank decreases with increasing distance between it and the
original sample.</p>
          <p>The strength of the structural position is the main indicator that
determines the differences in the resources of network participants.</p>
          <p>Community analysis allows studying the stability of social structures.</p>
          <p>The simplest case of a linked group is a community where each
member is associated with everyone, and other members of the
network cannot be included in this group, since they do not have
Data dimensionality
reduction methods
Structural equivalence of
network participants
Role algebras
Analysis of dyads and triads
Stochastic models
Network dynamics models
Algorithmic tools for
analyzing the evolution of
networks
Analysis of network
development graphs
Predicting bond formation
Ontology-based models
connections with all members of the community.</p>
          <p>The projection of the network vertices into the Euclidean space of
reduced dimension is considered to describe the relationships
between the rows and columns of this matrix. As a result, it is
possible to visualize changes in the status of a network user against
the background of changes in the statuses of subgroups.</p>
          <p>The approach is the opposite of exploring related groups.</p>
          <p>Participants are equivalent when they occupy the same positions in
the social structure of the network, that is, when the structure and
type of interaction of these participants with others are equivalent,
while the equivalent participants in the network should not interact
with each other.</p>
          <p>The direction of analysis of social networks, which focuses on
identifying the logic of interactions of network participants in block
models, makes it possible to identify similarities in the principles of
relationships between participants in various social networks
Dyads are a set of two network members (vertices) and all
interactions (edges) between them. The dyad for each type of
interaction can be in one of four states: there is no connection
between the participants, the connection is directed from the first
participant to the second, the connection is directed from the second
participant to the first, mutual connections of the participants. The
analysis of dyads helps to establish the probability of the presence of
an edge between them, the degree of dependence on the properties
of participants, to determine the conditions and directions of
information transfer, etc. For triads (three interacting participants),
questions of transitivity of interactions are additionally investigated.</p>
          <p>The main idea behind probabilistic directed graph models is that
each social network can be viewed as a realization of a random
twodimensional binary array.</p>
          <p>Consider the strength and speed of changes in connections in social
networks (graph evolution models, “closed triangle” model, “forest
fires” model)
The algorithms are based on dynamic programming, exhaustive
search, maximum matching, and greedy heuristics. The main focus is
on identifying approximate user clusters and their temporary
changes.</p>
          <p>Approaches to the analysis of network evolution based on the
paradigm of association rule mining and frequent pattern mining.</p>
          <p>The rules of the evolution of the graph, a new type of frequency
models are introduced, and the problem of finding typical models of
structural changes in dynamic networks is considered.</p>
          <p>Graph evolution models are usually created to evaluate the general
statistical properties of existing graphs. You can also try to calculate
whether two specific vertices will be connected to each other after a
certain period of time. This is a computational task based on the
analysis of the evolution of a social network in time and is called the
problem of predicting connections.</p>
          <p>Parameters of social networks can be evaluated using ontologies.</p>
          <p>
            First, an analysis of the types of network elements is performed:
people, objects (music, photos, videos, messages), interactions
(knows, reports, comments, etc.). Then the authors use the existing
ontology resources and additional options for all kinds of
relationships. The FOAF ontology is used to identify the members of
a social network and the content they add to the network. A new
version of SCOT is used to describe tags.
* Summarized from [
            <xref ref-type="bibr" rid="ref8">8</xref>
            ]
          </p>
          <p>Among the many existing models for analyzing social networks, the most interesting are those that
can actually be implemented on the basis of available statistical information (metrics of a social
network and its participants).</p>
          <p>
            One of these characteristics is the “level of trust.” The algorithm for calculating the level of trust
(TrustRank) [
            <xref ref-type="bibr" rid="ref9">9</xref>
            ] was created to separate informative web pages from spam. For a control sample,
experts manually assess the trust level of a small number of sites that can be considered reliable.
These sites are taken as a benchmark. Further, the algorithm is based on the statement that good sites
rarely link to bad ones, but bad ones very often link to good ones. TrustRank is a value that gives an
estimate of whether a particular site can be trusted, assuming that it does not contain spam. The more
links there are on the site, the less  trust  is  “passed” on each such link. TrustRank decreases with
increasing distance between it and the original sample.
          </p>
          <p>
            To strengthen the results of calculating the level of trust, it is advisable to use the indicator
“Strength of the structural position of a participant,” which determines the differences in the resources
of network participants. In the theory of network exchange, to measure this characteristic, [
            <xref ref-type="bibr" rid="ref10">10</xref>
            ] the
GPI index of the participant’s strength is introduced vi (Genuine Progress Indicator):
 −1
(1)
 =1
where  [ ] is the number of disjoint paths of length k, passing through the vertex vi. Participant
strength vi compared to the strength of the participant v j calculated as GPIij = GPIi - GPIj.
          </p>
          <p>
            It is advisable to track the spread of malicious information from centers of influence using
“Network Dynamics Models” [
            <xref ref-type="bibr" rid="ref11 ref12">11, 12</xref>
            ].
          </p>
          <p>
            Graph evolution models [
            <xref ref-type="bibr" rid="ref13">13</xref>
            ] according to which, when a new vertex is added to the network,
vertices are selected to which one can join using the joining preference rule. Also, the selection of a
vertex can be performed randomly or by “copying” some of its external links.
          </p>
          <p>
            Triangle-Closing Model [
            <xref ref-type="bibr" rid="ref13">13</xref>
            ] states that new vertices added to the network tend to close the
triangle. If we assume that the connections that arise between the participants form a triangle, then an
“open” triangle occurs when two participants can be connected with each other only through the third,
that is, one of the three connections is missing. When  a  third  bond  is  added,  a  “closed” triangle is
obtained.
          </p>
          <p>
            The model of “forest fires” [
            <xref ref-type="bibr" rid="ref14">14</xref>
            ] is, in a sense, a generalization of the closed triangle model. The
new vertex is joined to the existing one by selecting a subgraph containing this vertex and connecting
it to all vertices of this subgraph. The process begins at the selected vertex and resembles the
propagation of a fire through all vertices of the network.
          </p>
          <p>
            In addition, studies [
            <xref ref-type="bibr" rid="ref15">15</xref>
            ] have shown that the parameters of social networks (diameter, number of
participants, average path length, etc.) can be estimated using ontologies. First, an analysis of the
types of network elements is performed: people, objects (music, photos, videos, messages),
interactions (knows, reports, comments, etc.). Then the authors used the existing ontology resources
and added options for all kinds of connections, including “dad,” “mom,” “friend,” applied the FOAF
ontology to determine the participants of the social network and the content that they add to the
network. A new version of SCOT was used to describe the tags. An ontology SemSNI (Semantic
Social Network Interactions) of interactions in a social network (page visits, comments, private
messages) and an ontology for the analysis of social networks SemSNA were created. With the help
of these ontologies, within the framework of the semantic analysis of a social network, it was possible
to calculate the parameters of the subgraphs of a social network for different types of semantic
relations (“family,”  “I like” / “favorite,” “friendship”  /  “isFriendOf”) and types of interactions
(“Comments,” “creates a message,” etc.).
          </p>
        </sec>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Results Discussion</title>
      <p>However, to build an effective security system for multimedia content in social networks, it is
necessary to develop an algorithm based on the use of available information about participants,
groups, and communities. This will allow developing a mechanism for identifying threats and
identifying the sources of their occurrence.</p>
      <p>To develop a methodology for constructing security systems for multimedia information resources
in social networks, the concept of modeling the behavior of members of a social network is proposed,
which is implemented at three levels.</p>
      <p>At the first level, an element of a social network (agent or actor) is determined, the behavior of
which forms the behavior of the social network as a whole, and is decisive for the study and
construction of a security system. At this level:</p>
      <p>1. A set of actions of an individual element of a social network is determined, which together form
behavior.</p>
      <sec id="sec-4-1">
        <title>2. The probabilities of the implementation of certain actions are determined.</title>
      </sec>
      <sec id="sec-4-2">
        <title>3. Information multimedia resources associated with a particular action are determined.</title>
      </sec>
      <sec id="sec-4-3">
        <title>4. Possible attacks aimed at the corresponding information resources are determined.</title>
      </sec>
      <sec id="sec-4-4">
        <title>5. Cost indicators of the corresponding information resources are determined.</title>
        <p>At the second level, models of collective behavior (group dynamics) are built. At this level:</p>
      </sec>
      <sec id="sec-4-5">
        <title>1. Models of influence in the group are determined.</title>
        <p>2. The dynamic characteristics of the group’s behavior are determined—stability, coordination of
actions, self-organization of the group, temporal characteristics of the dynamics of behavior.</p>
      </sec>
      <sec id="sec-4-6">
        <title>3. Characteristics of openness, isolation, or closedness of the group are determined. At the third level, threats are identified that are directed at the platform of the functioning of the social network as a whole. At this level, a classifier of threats specific to social networks and their multimedia content is formed (or modified).</title>
        <p>The formed complex of tasks, separated by levels, makes it possible to form an economically
grounded methodology for constructing a security system for multimedia information resources of
social networks.</p>
        <p>The methodology construction process consists of five stages:</p>
      </sec>
      <sec id="sec-4-7">
        <title>1. Analysis of a social network and possible attacks on it.</title>
      </sec>
      <sec id="sec-4-8">
        <title>2. Analysis of a social network and possible attacks on it.</title>
      </sec>
      <sec id="sec-4-9">
        <title>3. Development of models of the social network group level.</title>
      </sec>
      <sec id="sec-4-10">
        <title>4. Development of platform-level models for the functioning of a social network.</title>
        <p>5. Development of methods for determining the most likely threats and assessment of their cost
indicators.</p>
        <p>The inclusion of economic indicators in the model for analyzing the security of multimedia
information resources in social networks will expand the capabilities of detecting threats and sectors
of influence (critical nodes) in social networks.</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>5. Conclusion</title>
      <p>The use of standard models of analysis of social networks at the present stage does not allow
identifying the sources of threats to the security of multimedia information resources in social
networks. This is primarily due to the fact that the main tool of influence is multimedia content,
which, unlike text content, is not subject to indexing to increase search speed. Mass identification of
multimedia content in modern conditions is possible only on the basis of the name of the file itself and
hashtags on the corresponding page. This problem critically affects the development of effective
models for analyzing multimedia information resources in social networks and requires the
development of a new methodology for identifying and countering information security threats.
6. References</p>
    </sec>
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