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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Method of random dynamic control transfer between network nodes for a partially centralized OS security</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Lukasz Kopania</string-name>
          <email>l.kopania@uthrad.pl</email>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff3">3</xref>
          <xref ref-type="aff" rid="aff4">4</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>2 Silesian University of Technology</institution>
          ,
          <addr-line>Akademicka str., 2А, Gliwice</addr-line>
          ,
          <country country="PL">Poland</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Kazimierz Pulaski University of Technology and Humanities in Radom, Department of Informatics</institution>
          ,
          <addr-line>Jacek Malczewski</addr-line>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Khmelnytskyi National University</institution>
          ,
          <addr-line>Khmelnytskyi, Instytutska street 11, 29016</addr-line>
          ,
          <country country="UA">Ukraine</country>
        </aff>
        <aff id="aff3">
          <label>3</label>
          <institution>Yuriy Stetsyuk</institution>
        </aff>
        <aff id="aff4">
          <label>4</label>
          <institution>str.</institution>
          ,
          <addr-line>29, Radom, 26600</addr-line>
          ,
          <country country="PL">Poland</country>
        </aff>
      </contrib-group>
      <abstract>
        <p>This paper analyzes the current threat level posed by malicious software to protected specialized OSs in relation to their resistance to leaks of confidential information. A model describing the interaction of protective mechanisms within a centralized security system for a network node OS is presented, which allows building a security architecture of a network OS, in which the problem of leakage of confidential information during attacks on the system's RAM is minimized. This is achieved by incorporating a marking mechanism that controls the channels through which confidential information passes at the memory page level. The principles of building centralized and partially centralized OS security systems and methods of organizing the operation of their security mechanisms are considered. A method of random dynamic transfer of control between nodes of a computer network is proposed as a way to increase the resistance of a computer network to leakage of confidential information and eliminate the bottleneck of a centralized system. Its feature is the synchronization and updating of the central database of privileges and the network state by replicating the local databases of network nodes and ensuring the availability of a backup control node, which is in constant readiness in case of failure. A graph model of the states of the central node of the network is presented, in which the main sequence of its states involved in the dynamic transfer of control between nodes of the computer network and the states corresponding to the most probable possible emergency situations are highlighted. A number of experiments were conducted and a comparative analysis of the effectiveness of centralized and partially centralized OS security systems was performed.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;operating system</kwd>
        <kwd>protective mechanism</kwd>
        <kwd>information leak</kwd>
        <kwd>centralized system1</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>The revolution in the field of information technology has resulted in many aspects of human
activity becoming critically dependent on various physical or virtual technological
advancements, which is especially true for information technology. Planetary society has
entered an era of its existence, where information has become the dominant resource that
determines the success of development in any field of its activity. Enormous resources of the
modern world economy are directed to its processing, storage, and provision of information
services.</p>
      <p>At the same time, it must be recognized that all information activities of humanity are under
the constant negative influence of attackers and malicious software, which is also in constant
development. Therefore, the issue of ensuring information protection and the stability of
information systems to its leakage becomes particularly relevant.</p>
      <p>The analysis of the situation in the information systems protection sector shows that the
task of ensuring information protection remains extremely relevant. Despite the large number
of methods developed by scientists to protect information systems, it cannot be considered
solved.</p>
      <p>In this paper, the emphasis of the information protection problem is aimed at increasing the
efficiency of network OS security systems, increasing their resistance to leaks of confidential
information through random dynamic transfer of control between network nodes.</p>
    </sec>
    <sec id="sec-2">
      <title>2. Related work</title>
      <p>Operating systems (OSs) have evolved significantly, transitioning from universal OSs to
specialized secure OSs, which are used in critical environments where information loss is
unacceptable under any circumstances. These include government and military systems,
various financial institutions, and corporate information systems, where data security is of
paramount importance. Today, this is not only a purely scientific or technical concept, but also
a legal one. The requirements for such systems are outlined in the US standard developed by
the National Institute of Standards and Technology (NIST), as well as in international standards
[1].</p>
      <p>Today, there are many incident response systems and approaches that can be used to
improve the level of security [2, 3] in networks in terms of counteracting the leakage of
confidential information. It has been established that OSs operating as part of cyber-physical
systems that use CBTC wireless data channels are vulnerable to attacks due to the low resilience
of their intrusion detection mechanism (IDS) based on machine learning [4], which can detect
only known attacks contained in training data sets and is insensitive to new types of attacks. In
order to eliminate the above problem, in [5], a more advanced IDS mechanism based on transfer
learning for the CBTC system is proposed. It uses an optimized one-dimensional convolutional
neural network block and long-term short-term memory to automatically extract spatial and
temporal characteristics from the source data and a new method of knowledge transfer, which
made it possible to detect new types of attacks. In [6, 7], an improvement of intrusion detection
systems (IDS) when operating OS with data in clouds is proposed based on the use of a
combination of the fuzzy clustering kernel (KFCM) and the optimal fuzzy neural network of
type 2 (OT2FNN), as well as the E-SGX protection mechanism [8].</p>
      <p>In [9], a distributed network system with an intrusion prevention system based on the Spark
structure and the dynamic model of information security theory is proposed. Its architecture
and functional structure are built by improving the Spark algorithm. Another similar
mechanism for mitigating attacks on computer networks is proposed in [10, 11].</p>
      <p>Another option for building a system for early detection of potential channels of attack on
computer systems is shown in [12, 13], the architecture of which includes agents of different
types and a certain number of instances, specializing in solving the problems of detecting
potential channels of attack on a computer system and interacting with each other, which
jointly solve the general problem of detecting intrusion into a computer system [14]. In [15], a
method for detecting ADRs at endpoints based on event identifiers using deep learning is
proposed. Event identifiers are understood as the behavior of ADRs, which are monitored and
collected in the OS kernel [16].</p>
      <p>In [17, 18], the use of intelligent deep learning methods in intrusion detection systems in
computer networks is proposed. Within the framework of this approach, the WNIDS method is
implemented, within which an SDN controller operates, which effectively monitors and
manages network devices, analyzes data sets. It is stated that a deep learning method called
Bidirectional LSTM (BiLSTM) is implemented based on the WNIDS model, which allows for
effective intrusion detection in the SDN-IoT network. In [19], two variants of the FTNPA
algorithm are presented: decentralized and centralized. The first variant implements local
recovery, when a mobile node is placed in a certain place to help the affected area. The second
variant uses a centralized detection method, where the recovery method creates alternative
paths of mobile nodes to the destination node.</p>
      <p>Much attention has been paid by scientists to improving the operation of OS protection
mechanisms, namely its kernel [20, 21]. A model of a centralized OS security system for new
OS architectures has been proposed [22].</p>
      <p>An interesting solution is to supplement the OS security systems with the DiSAuth
authorization system [23], which provides a secure algorithm based on the Domain Name
System (DNS) and blockchain, ensuring its resistance to tampering, preserving confidentiality,
and protecting data from leakage. [24] raises the issue of minimizing the granting of access
privileges to resources as a way to increase resilience to information leaks.</p>
      <p>The integration of artificial intelligence into computer networks is one of the advanced
technologies. It is assumed that the concept of applying artificial intelligence will solve the
problems faced by computer networks, especially with regard to eliminating the threat of
information leakage [25]. Methods for increasing network resilience by using specialized
cryptographic modules at the transport layer (TLS) together with secure hardware security
modules (HSMs) are also proposed [26].</p>
    </sec>
    <sec id="sec-3">
      <title>3. Formulation of the problem</title>
      <p>A study of methods to enhance the resistance of specialized OSs to information leaks has shown
that, despite modern OSs formally meeting the aforementioned criteria, they still require
additional protection mechanisms when used in information systems designed to process
confidential data.</p>
      <p>The analysis of the current state of the level of threats from malicious software to today's
protected OS confirms that most of them are due to the conceptual approach implemented in
the OS, which is based on the implementation of a distributed administration scheme for
protection mechanisms. Within the framework of this approach, the user in the OS is considered
as a trusted person who is an element of the administration scheme and has the ability to assign
access delimitation rules. At the same time, he is not perceived as a potential attacker who can
knowingly or unknowingly carry out unauthorized access to information.</p>
      <p>Thus, the OSs currently in existence are unable to guarantee one hundred percent resistance
to information leakage due to the existence of vulnerabilities on the one hand, and on the other
hand, due to being under constant threat from the PPS, which is only increasing. Without the
implementation of additional OS protection mechanisms based on centralized and partially
centralized security systems, countering information leakage and, in general, unauthorized
access to confidential information will be ineffective.</p>
    </sec>
    <sec id="sec-4">
      <title>4. Methods and material</title>
      <p>4.1. Centralized and partially centralized network OS security systems
Consider the graph model of the OS security system shown in Figure 1. Here, the functional
modules of the OS security system correspond to the vertices of the graph, and the directed
edges indicate the interaction between the modules, determining the algorithm of its operation.
The main interactions:
•
•
•
•
•
the central security management module (CSMM) transmits security policies, including
confidential information marking policies, through the Policy Distribution module to
the peripheral security modules PSM1 – PSMn;
the peripheral security modules PSM1 - PSMn transmit monitoring data through the
Monitoring module to the central CSMM module for analysis;
the Monitoring module transmits the results of monitoring the correctness of
confidentiality markers to the Labeling module;
the Labeling module transmits information about the marking of confidential
information to the agents to the peripheral security modules PSM1 - PSMn for further
use at the memory page level;
AuthM authentication, AuthZ authorization, EncM encryption, and NetSec network
security modules interact with the Labeling module when performing their functions.</p>
      <p>The proposed model of a centralized security management system allows us to obtain an OS
security architecture that will be free from the problem of confidential information leakage
during low-level malware attacks. This is achieved by including a marking mechanism in it, the
feature of which is the control of channels for passing confidential information at the level of
memory pages.</p>
      <p>If we take a machine with an operating system with the given security system model as the
basic node of a computer network, we will get a network where centralized privilege
management will be implemented in each individual node, but the network itself will have
decentralized management, with all the security problems inherent in this model. If we transfer
network management to one of the network nodes, we will get a network system with
centralized management. This management model has a number of significant advantages, such
as:
•
•
simplified management, since there is no need to coordinate actions between several
management modules - administration is carried out through a single CSMM module
(Figure 1);
unification of privilege management policies and resource management according to
the same rules, security policies and protocols are installed in one place, which ensures
the unity of network management, facilitates administration, since changes in policies
are applied simultaneously to the entire network;
centralized monitoring, means that all information about the state of the network and
its nodes comes to a single module, which greatly facilitates the detection of threats,
simplifies analysis and decision-making.</p>
      <p>However, a centralized control system has a number of potentially threatening
problems. The main ones are:
the so-called "single point of failure" (Single Point of Failure), when the failure of the
central module makes the network vulnerable, creating a high risk of its continuous
operation;
vulnerability to malware attacks. The very presence of a central control node makes it
a prime target for various kinds of destruction, as a successful attack can give access to
the entire network.</p>
      <p>The purpose of this study is to find a solution that would allow preserving the main
advantages of a centralized system, while getting rid of its biggest problems.
4.2. Method of dynamic transfer of control between network nodes with
replication of the network OS security privilege base
As one of the ways to overcome the shortcomings of the centralized OS security system while
preserving its positive qualities, a method of dynamic control transfer between network nodes
during its operation is proposed (Figure 2). The method is based on the constant migration of
the control center across network nodes, which allows getting rid of the main drawback of a
purely centralized approach - the presence of a bottleneck in the form of vulnerabilities in the
central control module.</p>
      <p>According to the proposed method, a computer network is represented as a set of nodes
, whose OS security systems have central control modules CSMM:</p>
      <p>= {  1,  
where: n is the number of network nodes.</p>
      <p>2, … ,  
 }
(1)</p>
      <p>In this case, each CSMM module of the node is associated with the privilege base B privileges
which in the current mode serves as the local base of the node, and when the node in the process
of dynamic transfer of control takes over the function of the central network control module, it
is updated to the level of the main network privilege base. All local privilege bases of network
nodes can be represented by the set:</p>
      <p>= {  1 ,</p>
      <p>Let us define the state of the system     
preceding the transfer of control, as:
2, … ,    } (2)
at time t, which corresponds to the moment
     ( ) = ( 
 
( ),  
 
( ),</p>
      <p>)
set that owns a token at time t
- backup control node at time t in
the network,</p>
      <p>– management token.
where:</p>
      <p>( ) ∈  
(is the network control center),  
- a node from the</p>
      <p>( ) ∈</p>
      <p>As can be seen from the definition of the network state (formula 3), a feature of the method
is the transfer of the functions of the central control module to the next node by sending it a
control token. We describe the transfer of the token as a transition:
     (  ) = ( 
 
(  ),  
 
(  ),  
whose selection rule is given by the formula:
= ( 
 
(  +1),  
 
(  +1),  
- a new control node, randomly selected from the set  
∕{
 
 +1 ≈ 
( 
∕{
 })
where:</p>
      <p>() – a function that provides the same probability of choosing any node
from among the active ones, excluding the current node, as the control node  
- the current control node, after transferring control to the  
 +1 module, performs the

,  
function of a backup control node,  
transmitted between network nodes to determine the current control module (CSMM). At one
point in time, only one network node owns the token. Thus, it serves to coordinate the network
state, transfer control, avoid conflicts, and prevent multiple nodes from simultaneously
performing control functions. In order to maintain its integrity, the token is digitally signed.
(3)
(4)
 }</p>
      <p>,
(5)</p>
      <p>An important point of the dynamic control transfer method is the updating of the main
privilege base</p>
      <p>+1 for the node to which control of the computer network is
of active network nodes at the time of changing the network control center.
transferred. It is obtained during the replication procedure of the local privilege bases</p>
      <p>In the current mode of operation, the node uses the local privilege base to the maximum,
and when transferring the functions of the central control node to it, it activates the main base.
It is assumed that each node stores its local privilege base, and the main base of the control
are allowed for replication, creating a set of privilege bases for replication  
which in the general case may not coincide with the set  
:
 
where:      
 

 ,      ( 
←     ( 
 , 
  (</p>
      <p>))
 )
- filter local bases  

=      (</p>
      <p>) - the condition for including the local base  
 in the replication set when filtering local bases is its membership in the active
Replication will be successful if local databases that are up-to-date participate in it. For
, its up-to-dateness can be determined through the Validate() function:
      (</p>
      <p>) = 1, here the value of the function equal to one means that it is relevant.
conditions:
The condition for the relevance of the  
 basis is that it falls under the following
bases subject to replication:
 

Now, when performing the replication
operation
on
the elements of the set
 
will be obtained, which does not contain incorrect data from local, out-of-date privilege bases
and local privilege bases of inactive nodes:</p>
      <p>, the current main privilege base for the central network management node
 ) = 1 - database synchronized;
 ) ≤△    - the time of its last update does not exceed a certain set</p>
      <p>)- the local privilege base is not corrupted.
elements in the set</p>
      <p>Given that each local privilege base  
will now look like this:</p>
      <p>must be up-to-date, the rule for including new
 
←     ( 
  ( 
 ) ∧ 

( 
 )
Taking into account this rule, we obtain a formula for all elements of the set of local privilege
  (</p>
      <p>( 
maximum period △</p>
      <p>;
       ( 
= 1)
 
= { 
 , 
 |
      
node  
node.
some 
•
•
•
 
 
+1
= 
( 
 
)</p>
      <p>The transfer of control from the current central module to the next one will be successful if
the computer network system is in the        (  ) state and the next k+1-th control node has
an up-to-date primary privilege base  
+1 . In this case, the node that has just
transferred control to the next central node goes into reserve, maintaining its ability to return
to the central node function.</p>
      <p>This approach to implementing the method practically makes it impossible to lose the
privilege base and does not require constant access to the global network, as in the case of its</p>
      <p>M CSMM
(6)</p>
      <p>,
by condition,
 of the i-th
(7)
(8)
(9)
storage in cloud storage, or implementation in the form of transactions in the blockchain
network, maintaining a high level of autonomy inherent in corporate networks. At the same
time, high resistance of the computer network as a whole to the effects of various types of
destruction is also ensured and, accordingly, the probability of leakage of confidential
information is reduced. Thus, the method ensures the continuity of network operation, data
consistency and system security.
node  
module</p>
      <p>Now we can formulate the main steps of the dynamic control transfer method:
Step 1. Preparation for control transfer. The state in which the current central security
management module</p>
      <p>(Figure.1) of the set M CSMM is located is evaluated, where the
presence of signs (timeout, system overload, scheduled maintenance) is checked. If at least one
of them is active, the current central module must transfer control functions to another network
module from the number of active nodes that will take control of the network. Then the current
 +1. If at least one sign is present, the current module determines the next  
 +1
 checks the relevance of the main privilege base  
 +1 of the node that
is to take over the functions of the central control node. If necessary, its replication or
synchronization is performed.</p>
      <p>Step 2. Transfer of the current system state, which includes the transfer of active sessions,
security policies and system monitoring status, event log data. The current module  
initiates a check of the correctness of the received data by the successor module  
 +1 and

the relevance of the privilege base</p>
      <p>+1, after which it notifies the current module</p>
      <p>of its readiness to perform the functions of the central node.</p>
      <p>Step 3. Activation of the new module. The current  
the successor in the form of a management token  
 module sends a notification to
, while all other active nodes of
the network are transmitted information about the new NM module. An important feature is
that at any given time only one node from the set  
 +1 owns the management token</p>
      <p>, which ensures its management role in the network.</p>
      <p>The old module is deactivated, but at the same time remains ready as a backup module,
periodically synchronizing its database of privileges and event logs in the system with the
database and logs of the new central node.</p>
      <p>Step 4. Having received the</p>
      <p>control token (Figure 2), the node activates itself as
the central module</p>
      <p>+1, taking control of the system. Its first step is to record in the logs
all actions related to the fact of transferring control to it, including the time of transfer, the
identifiers of the CSMM modules of the active nodes, the state of the privilege base. In addition,
the new module</p>
      <p>+1
functions of the network security system manager.</p>
      <p>notifies all active nodes of the system that it is ready to perform the
Step 5. System monitoring and control. In this step, the new  
 +1 module monitors the
security status of the system in order to detect possible failures or destruction. Constantly
informs the backup</p>
      <p>module about changes in the main privilege database in order to
maintain them in a state of maximum synchronization. Tracks the status of the signs of
transferring network control to the next node.
4.3. Algorithm for dynamic control transfer between network nodes
In order to further detail the work of the proposed method, we will display the steps of the
method in the form of an algorithm (Figure 4 and Figure 5).</p>
      <p>It should be emphasized that this algorithm is a law of the functioning of each node of a
computer network, but at each moment of time they are at different stages of its execution. Its
important feature in the implementation of dynamic transfer of control between the central
modules of the CSMM system of network nodes is based on the rule of continuity of network
operation and the prevention of leaks of confidential information.</p>
      <p>In general, the process of operating a computer network based on the dynamic control
transfer method is divided into several stages - the network startup process, the main stage, and
the failure recovery stage.</p>
      <p>The main stage is a cyclic movement along the trajectory, which includes the vertices of the
state graph (Figure 6) 3 – 4 – 5 – 6 - 3 … . Here, the third vertex of the graph corresponds to the
standby mode. This is the normal mode in which the network node is most of the time,
performing the functions assigned to it. Its central control module CSMM is subordinate to the
node CSMM module, which currently manages the security system of the entire network and
provides local control of the node security system in accordance with the security policies
implemented by the central module.</p>
      <p>From this state, the network node can enter the transition mode (vertex 4 Figure 4). In this
mode, the node's CSMM module has received a control token and is in the process of assuming
control of the network OS security system - it receives information about the system state,
active sessions and the privilege base, checks the consistency of data between nodes, which
corresponds to the execution of the algorithm (operators 6-8 Figure 4).</p>
      <p>From the state of the transition mode, the node, during the normal course of events,
transitions to a state in which it performs the functions of the central module CSMM (vertex 5
Figure 5), in another way - it controls the security system of the network OS, which corresponds
to the execution of the algorithm (operators 9 - 11 Figure 5). The node is in this state for the
period for which it is assigned to perform the functions of the central module of the network
security system control, or until the onset of an emergency situation (edge 5-7 Figure 6). If,
during the execution of the algorithm (operator 11 Figure 3), at least one sign of transfer of
control is detected (expiration of the period, intervention of the system administrator), then the
node transitions to the reserve state (vertex 6 Figure 4). In this mode, it is in a state of readiness
to return to performing the functions of the central module CSMM.</p>
      <p>Це This means that the main privilege base of this node is constantly maintained in an
upto-date state, which allows for the fastest possible replacement of the current central node if
necessary in the event of an abnormal development of events (edge 6-5 Figure 6). In the case of
a normal development of events, after the next iteration of the dynamic change of the control
center, the node will return to the standby mode (vertex 3 Figure 6), closing the main sequence
of normal states in which a computer network node can be.</p>
      <p>In the event of an emergency situation of a local failure, any node, regardless of its current
state, will transition to the emergency state (vertex 7 Figure 6). In this case, it will be excluded
from the number of active nodes in the network. From this state, according to the state graph
(Figure 6), the node transitions to the unavailability state (vertex 1 Figure 6).</p>
      <p>In this state, after eliminating the cause of the failure, it waits for a reconnection to the
network. When connecting to the network, it automatically enters the synchronization state
(vertex 2 Figure 6). In this state, the local privilege and policy database is updated to the current
state, and consistency with other nodes is checked. The synchronization processes are
completed by including the node in the active list, and the node itself enters the waiting state
(vertex 3 Figure 6).</p>
      <p>When starting the network or in case of large-scale failures, the network operation is
restored according to the algorithm shown in figure 5. It takes into account situations that may
arise when the network operation is restored after a failure. Since not all nodes restore their
operation in the network at the same time when starting the network, the first node that will
take control will be determined as the node with the highest priority among the nodes that are
currently active (operator 2 Figure 5).</p>
      <p>The node thus determined, whose CSMM module will perform the function of the central
module of the OS security system, generates a control token and sends it to all other active
nodes of the network that it is the control center of the system (operator 4 Figure 5).</p>
      <p>In the subsequent steps, the algorithm involves synchronizing the privilege database with
the local databases of active nodes in order to recreate the current main privilege database
(operator 5 Figure 5). The next step of the algorithm is to collect information about session
opening and other information about the network status (operator 6 Figure 5). In the future, the
algorithm of the central control module when starting the network after a failure coincides with
the algorithm shown in figure 5.</p>
      <p>Standby mode     ;
Network Control Center Mode  
Standby module mode    
.</p>
      <p>;</p>
      <p>Other states of the transition graph have their own specialization, which lies outside the
main sequence. Thus, the states corresponding to vertices 1 and 2 of the graph (Figure 6) serve
to bring the node to the main trajectory. Vertex 7 corresponds to the emergency state of the
node, which always occurs in a physical system. Exit from this state is possible through vertices
1 and 2 of the graph.
4.4. Determining the effectiveness of the dynamic control transfer method
The partially centralized OS security system is based on the application of the proposed method
of dynamic control transfer between computer network nodes. To assess its effectiveness, we
will use a set of mathematical and probabilistic models that take into account the following
indicators:</p>
      <p>The main sequence of states of an active node in the network is described by transitions
between the vertices of the state graph 3-4-5-6-3-… (Figure 6). Thus, each node has four main
states. To simplify understanding, vertices 4-5 of the graph can be conditionally combined into
one. Then the main sequence of transitions of the graph (Figure 6) for the node will be limited
to three states:
•
•
•
•
•
•
the probability of leakage of confidential information, which takes into account the
effectiveness of the protective mechanisms of the network node's OS and the
vulnerability of the computer system    ;
threat detection time         ;
security transaction processing time  Performance.</p>
      <p>Taking into account the above, the formula for the efficiency of a computer network, in
which all three parameters will be combined, taking into account their weight, will take the
form:
     =  1 × (1 −   
) +  2 × (</p>
      <p>where:  1,  2,  3 - weighting factors of efficiency parameters.    - the likelihood of
leakage of confidential information.          - threat detection time.    
network control node performance.</p>
      <p>The expression of formula (10) corresponds to all the relations for the centralized OS security
system, so let us rewrite it taking into account the notations adopted for it:
) +  2 × (
1
1
)
+  3 ∗</p>
      <p>Since the operation of a partially centralized system is based on the use of a method of
dynamic transfer of control between network nodes, this fact should be reflected in its efficiency
formula. This method reduces the vulnerability of the OS security system, but at the same time,
it also reduces to some extent the performance of the system as a whole. Dynamic change of
the control center requires time to synchronize the privilege bases. Let us denote it as
TSynchronization, partially . Taking into account this parameter, the efficiency formula for a partially
centralized system will take the form:
     ,  
 =  1∗ 1−   ,   
+  2 ∗</p>
      <p>1</p>
    </sec>
    <sec id="sec-5">
      <title>5. Experiments</title>
      <p>5.1. Setting up experiments
In order to determine the effectiveness of the dynamic control transfer method, several
experiments were conducted. For this purpose, a test environment was deployed based on the
use of a virtual computer network, which includes virtual nodes VM01 - VM04, which served
as target machines during the experiments (Figure 7). In addition to them, the network includes
an attacking machine VM00, with the help of whose software various types of attacks on
possible ways of leaking confidential information will be simulated. The attacking machine is
equipped with the Kali Linux OS and the Metasploit Framework attack simulator. The target
machines are controlled by the FreeBSD 13.1 OS with a centralized security system.</p>
      <p>All virtual machines run under the control of the Virtual Box hypervisor. With its help,
virtual machines are combined into a separate local virtual network necessary for conducting
experiments.</p>
      <p>The purpose of the experiment is to obtain data on the comprehensive stability of protective
mechanisms under the influence of threats acting on possible information leakage paths that
take into account such parameters as the probability of information leakage, the time of
detection of a malicious software attack, the performance of the central network node and the
time of control transfer between network nodes. The experiment includes simulation of
computer attacks of various types directed on all possible paths of confidential information
leakage of all nodes of the virtual network.</p>
      <p>To simulate various types of attacks, the Metasploit Framework simulator of the attacking
machine VM00 (Figure 7) was used. Under its control, a developed script file was launched,
which contains instructions in the Ruby language. The script file algorithm includes cyclic
simulation of attacks along all main leakage paths across all network nodes in the address range
(12)
(13)
192.168.10.12 - 15. At the time of the script file operation, the /tmp/k1/test.txt files were opened
on all target machines, simulating resources with confidential information. The results of the
experiment are information about the number of successful and unsuccessful attacks on the
corresponding nodes of the virtual computer network.</p>
      <p>In addition to the above information on the side of the attacking machine VM00, the
Result_atack.txt file recorded the start data of each attack, the IP address of the target machine,
and the type of attack. If the security system of the corresponding target machine, to which the
attack vector was directed, detects a threat, then after blocking it, it will make entries in its
system logs security.log and audit.log upon this event. The difference between the start time of
the simulation recorded in the Result_atack.txt file of the attacking machine and the time of its
detection recorded in the security.log log of the corresponding target machine will correspond
to the time of threat detection.</p>
      <p>The results of comparing data from the Result_atack.txt file of the attacking machine VM00
(Figure 8) and the security.log files (Figure 9) of the corresponding target machines VM01-VM04
are presented in Table 1 in an averaged and normalized form. Since the attacking machine and
the target machines are in the same time space (one time scale) of the physical machine, the
error in measuring the duration of the attack detection period will be minimal. The situation
when the record of the start of the simulation recorded in the Result_atack.txt file does not have
an associated record in the security.log logs of all target machines means that a successful attack
has occurred. An example of the comparison is highlighted in red (Figure 8, Figure 9).</p>
      <p>Another stage of experiments was aimed at obtaining data that would allow determining the
performance of the control node of the TPerformance</p>
      <p>TRequest at startup and TShutdown prompt , respectively. Then the performance of the central
node of the network will be determined as:
    
=  ℎ       .</p>
      <p>The processed experimental data are given in Table 1.
(14)
Using formula (14) and experimental data, we will calculate the performance of the central node
for a centralized system, for which we will substitute the corresponding values from Table 1:</p>
      <p>To calculate the effectiveness of the security system, we will use formula (10). To do this, we
will determine the values of the weight coefficients  1 −  3 present in this formula. To
determine their weight, we will use the linear hierarchy method, within which we will apply
an importance scale from one to nine: 1 - equal importance; 3 - weak advantage of one factor
over another; 5 - strong advantage; 7 - very strong advantage; 9 - absolute advantage. Guided
by this scale, we build a matrix of pairwise comparisons:</p>
      <p>Guided by this scale, we build a matrix of pairwise comparisons:
 ( ) =</p>
      <p>3 . Here, the columns and rows of the matrix are weight coefficients
 1 −  3, and its elements are the result of pairwise comparison. After performing the following
steps, we obtain:  1=0.633;  2=0.261;  3=0.106 . Now we can directly calculate the effectiveness
of the security system, for which we substitute the values into formula (11) for the centralized
OS security system:
1
 ,
(16)
= 0,633∗(1−0,0115)+0,261∗0,308+0,106∗0,921+0,688=1,5389</p>
      <p>Let us use inequality (3.32) to compare the calculated efficiency values of two variants of OS
security systems:</p>
      <p>The performance of the central node for a partially centralized system is calculated in the
same way:
=
  ℎ  
  
=
  
  ℎ   




=
0,142</p>
      <p>= 0,887
=
0,117
0,127
  
Similarly, for a partially centralized OS security system, we use formula (12):
     ,</p>
      <p>=  1∗ 1−   , 
+  3 ∗      
, 
 
1</p>
      <p>1
+   
+  2 ∗   
ℎ
1
, 
Let's display the result in percentages:
     ,
  
  ,  
1,397
∗ 100% = 1 −
∗ 100% = 9,2%</p>
      <p>The calculation shows that the effectiveness of a partially centralized OS security system,
despite its complexity, is significantly higher. In turn, the higher effectiveness of such a security
system means greater resistance to SPP, which in turn provides lower vulnerability to the
leakage of confidential information. As can be seen from the graph (Figure 10), the effectiveness
of a partially centralized OS security system is 9.2 percent higher than that of a centralized
system.</p>
    </sec>
    <sec id="sec-6">
      <title>6. Conclusions</title>
      <p>The proposed method of dynamic control transfer between network nodes with support for
replication of the main privilege base for a partially centralized OS security system made it
possible to preserve the main advantages of a centralized security system, especially with regard
to the system's resistance to information leakage, and at the same time get rid of its biggest
drawback - a bottleneck in the security system in the form of a central security module, the
failure of which leads to loss of control over the entire system.</p>
      <p>The efficiency of the OS security system using this method of computer network
management is at least 9.2 percent higher than a purely centralized approach.</p>
      <p>Another advantage of this method of dynamic control transfer is that periodic random
changes to the network control node with a high probability make the results of the attacker's
network reconnaissance irrelevant, thereby disrupting attacks on the network before they even
begin. This is explained by the fact that the network reconnaissance time is much longer than
the period of changing the network control center, which gives it the opportunity to evade the
attack in this way.</p>
    </sec>
    <sec id="sec-7">
      <title>Declaration on Generative AI</title>
      <p>The authors did not use artificial intelligence tools.
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