=Paper= {{Paper |id=Vol-3241/paper9 |storemode=property |title=Simulation Model of a Fuzzy Cyber Attack Detection System |pdfUrl=https://ceur-ws.org/Vol-3241/paper9.pdf |volume=Vol-3241 |authors=Ihor Subach,Vitalii Fesokha,Artem Mykytiuk,Volodymyr Kubrak,Stanislav Korotayev |dblpUrl=https://dblp.org/rec/conf/its2/SubachFMKK21 }} ==Simulation Model of a Fuzzy Cyber Attack Detection System== https://ceur-ws.org/Vol-3241/paper9.pdf
Simulation Model of a Fuzzy Cyber Attack Detection System
Ihor Subach1,2, Vitalii Fesokha2, Artem Mykytiuk1, Volodymyr Kubrak1,
and Stanislav Korotayev1
1
  National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", st.Verkhnoklyuchova, 4,
Kyiv, 03056, Ukraine
2
  Military Institute of Telecommunications and Information Technologies named after Heroes of Kruty, st.
Moscow, 45/1, Kyiv, 01011, Ukraine


                 Abstract
                 The method of applying a simulation model of a fuzzy cyberattack detection system is
                 considered. The functional diagram of the simulation model is given. The block diagram of the
                 simulation model is considered and the purpose of its elements is described. The main steps of
                 using a simulation model for conducting an experimental study of evaluating the effectiveness
                 of models and methods for detecting cyber attacks based on the theory of fuzzy sets and fuzzy
                 inference are described. The procedure for generating initial data is given, the classes of
                 cyberattacks to be detected are defined, the vectors of cyberattack features are identified, the
                 parameters of the studied traffic are described, the types of membership functions are defined
                 to formalize expert knowledge and represent it in the knowledge base in the form of fuzzy
                 production rules. The issue of parametric adaptation of membership functions to clarify the
                 subjective judgments of experts are considered. To implement the possibility of detecting
                 polymorphic cyberattacks, the procedure for determining the required number of the most
                 important features for each known class of cyberattacks, represented by fuzzy sets and
                 linguistic variables that characterize them quite fully, is described. A comparative analysis of
                 the results of modeling the process of detecting cyber attacks based on the proposed approach
                 with existing methods for detecting cyber attacks was carried out, based on the theory of fuzzy
                 sets and fuzzy logic, artificial immune systems and neural networks in terms of accuracy.

                 Keywords 1
                 Cybersecurity, cyber attack, IDS, simulation model, fuzzy set theory

1. Introduction

   In [1, 2] the architecture of a promising fuzzy intelligent system for detecting cyber attacks was
proposed. It allows the security operations centers (SOC) operational personnel to make decisions on
their detection promptly and reasonably. It is based on the technologies of data mining, machine
learning, big data processing and artificial intelligence (Figure 1).
   The proposed architecture consists of the following components [2-10]:
   information collection subsystem - a set of sensors on network nodes that collect and process primary
data on network activity;
   analyzer - the module of the first echelon of cyber attack detection - analyzes security events
(incidents) and on the basis of signature analysis classifies harmful activity as cyber attack;
   signature database - a dictionary of signatures of classified cyberattacks used by the component -
analyzer;



XXI International Scientific and Practical Conference "Information Technologies and Security" (ITS-2021), December 9, 2021, Kyiv, Ukraine
EMAIL: igor_subach@ukr.net (I. Subach); vitaliifesokha@gmail.com (V. Fesokha); mukuta8888@gmail.com (A. Mykytiuk);
volodymir.kubrak@ukr.net (V. Kubrak); meduha1998@gmail.com (S. Korotayev)
ORCID: 0000-0002-9344-713X (I. Subach); 0000-0001-6612-1970 (V. Fesokha); 0000-0002-8307-9978 (A. Mykytiuk); 0000-0001-8877-
5289 (V. Kubrak); 0000-0003-3823-8375 (S. Korotayev)
              © 2021 Copyright for this paper by its authors.
              Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
              CEUR Workshop Proceedings (CEUR-WS.org)



                                                                                                                                     92
    statistical database - statistics of telemetry of network traffic for a certain period for its further use
in order to improve the system to adapt the parameters of the mechanism of detection of cyber attacks
to existing changes;
    scheduler - plans further actions of the system after processing by the analyzer (in case it detects a
cyberattack, the scheduler gives control to the response module to take measures to stop malicious
activity; otherwise, the scheduler gives control to the data analysis module detection cyber attacks
second tier, built on the basis of the developed model of cyberattack detection [8-11];
    fasificationblock - clear values of the studied parameters are turned into fuzzy (the degree of their
belonging to the term sets of linguistic variables specified by experts is determined). Fuzzy network
activity is taken into account based on the application of the model proposed in [8-11];
    fuzzy rule base: contains fuzzy production rules built by experts at the stage of preparing the system
for operation;
    adaptation module: performs primary parametric adjustment of membership functions by means of
genetic algorithms on the basis of a certain training sample and further training of the system if
necessary on the basis of statistical data to clarify the values of cyber attack detection mechanism;
    fuzzy inference block - a module for making decisions about the state of the network based on
determining the relationship between input data (telemetry of network traffic) and expert opinions by
means of fuzzy logic;




Figure 1. Architecture of a promising fuzzy intelligent system for detecting cyber attacks

    response module - generates requests and notifications to the console, takes protective measures to
block detected cyberattacks, as well as fills the database of statistical decisions on their decisions for
further use by the adaptation module;
    management console: module for configuring the cybersecurity officer of the system parameters.
    The application of the proposed IDS architecture allows to increase the efficiency of detecting
cyberattacks in near real time, based on the application of a multi-tiered approach to their detection. In
addition, it becomes possible to adapt the system to the detection of unknown types of cyber attacks
(zero day), as well as increase the efficiency of the cybersecurity officer on such indicators as efficiency
and soundness of decision-making.
    In [8-11] – models and methods for detecting known and polymorphic cyber attacks based on the
theory of fuzzy sets and fuzzy inference. Formally, the task of fuzzy identification of a cyber attack is
to find a solution to analytical expression that connects a set of parameters of the state of the system,

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on the basis of which its anomalous behavior is determined and an expert solution that meets them,
taking into account the weighting coefficients for fuzzy rules (Figure 2):
                                                           
             X *  x1* , x 2* ,, x n*  y  a1 j , a 2 j ,, a n j  D  d 1 , d 2 , d n , i  1, n, j  1, m,
                                               jk      jk        jk
                                                                                                                   (1)
where X  x1 , x 2 ,, x n  is a set of parameters of the information and communication system (ICS)
which are analyzed;
   y is a linguistic description of the expert decision (opinion) d j  D on the state of ICS;
    jk j is a numbers of combinations of values of             xi of the parameters of ICS state description,
corresponding to the value of d j .

                       Input Parameters
                                                                                    Solution:
                   (Signs of Cyber Attacks)
                                                                                Cyber Attack Class


                               x1                                                          d1
                                                   Fuzzy
                                                                      Logic
                               x2                knowledge                                 d2              d
                                                                      output
                                y  D.
                                 *




                                                    base                                   y *  D.




                                                                                           
                                
                                                   (fuzzy              unit
                                                                                           dm
                               xn                  rules)

Figure 2. Graphical interpretation of the problem of cyber attack identification

    To evaluate the effectiveness of the proposed solutions, a system simulation model (FIDM – Fuzzy
Intrusion Detection Model) was developed using the Fuzzy Logic Toolbox™ package,which provides
MATLAB® functions and the Simulink® block [13, 14, 15] for designing and modeling systems based
on fuzzy logic.

2. Functional and structural diagram of the simulation model

    The functional diagram of the simulation model is shown in Figure 3, where x1..xn are input
parameters and y is an output variable.
    The basis of the proposed simulation model is a modular diagram for organizing sequential iterative
interaction between its components: a data input module for analysis, a fuzzification module, a
knowledge base (KB), a fuzzy inference and defuzzification module [13, 14, 15]. The structure diagram
of the developed simulation model is shown in Figure 4.
    For the operation of the test data input module [16], is a set of statistical data on cyberattacks KDD
Cup 1999 Data (xlsx files) was used.
    The purpose of the fuzzification module is to represent the quantitative and qualitative values of the
studied parameters using term sets and linguistic variables. Incomplete and uncertain data on network
activity were taken into account by applying the developed model of cyber attack detection.
    Additional rules generation module was used to create new fuzzy production rules in the knowledge
base by intersecting fuzzy sets of linguistic variables of previously existing rules and the most
significant linguistic variables predefined by an expert for each class of cyberattacks.
    The knowledge base is a set of fuzzy production rules built by an expert.




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Figure 3. Functional diagram of the FIDM simulation model




Figure 4. Structure diagram of the developed simulation model

   The purpose of the fuzzy inference module is to generate a decision about the state of the information
and communications network based on determining the relationship between input data and expert
conclusions using fuzzy logic.
   The defuzzification module was used to convert the obtained values of the fuzzy inference into crisp
ones.

3. Methodology of applying the simulation model

   Step 1: Defining is a set of cyber attackstatistics: KDD Cup 1999 Data [16].
   Step 2. Defining the classes of cyberattacks to be detected [16]: Denial of Service, Remote to Local,
User to Root, Probe and normal states of the ICS.
   Step 3. The input of the simulation model was fed with vectors of cyber attacks of the KDD Cup
1999 Data set in the number of: known – Denial of Service – 4264, Remote to Local – 1020, User to


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Root – 52, Probe – 3231; normal states of the information system – 1000; polymorphic cyberattacks
built on the basis of known ones – 100. Thus, the total number of attribute vectors was 9667.
   For the study, 38 parameters of network traffic telemetry were selected based on the classification
proposed in the chosen data set on cyberattacks (Table 1).

Table 1
The studied parameters of network traffic
         Code                        Parameter                             Description
           x1            duration                           Connection time in seconds
           x2            src_bytes                          Number of bytes from source to
                                                            destination
           x3            dst_bytes                          Number of bytes in the response to the
                                                            client
           x4            land                               1 if the connection is from/to the same
                                                            host/port
           x5            wrong_fragment                     Number of false fragments
           x6            urgent                             Number of urgent packages
           x7            hot                                Number of hot indicators
           x8            num_failed_logins                  Number of failed registration attempts
           x9            logged_in                          1 if successful login; 0 unsuccessful
          x10            num_compromised                    Number of compromising conditions
          x11            root_shell                         1 if a root shell is obtained; otherwise 0
          x12            su_attempted                       1 if su root was executed; otherwise 0
          x13            num_root                           Number of root accesses
          x14            num_file_creations                 Number of file creation operations
          x15            num_shells                         Number of shell requests
          x16            num_access_files                   Number of operations to access file
                                                            control
          x17            num_outbound_cmds                  Number of FTP session output
                                                            commands
          x18            is_host_login                      1 if the login belonged to the hot list
          x19            is_guest_login                     1 if guest login
          x20            count                              Number of connections in the current
                                                            session in the last 2 sec.
          x21            srv_count                          Number of connections to the same
                                                            service in the last 2 sec.
          x22            serror_rate                        % of connections that had SYN errors
          x23            srv_serror_rate                    % of connection with an error in SYN
                                                            packet
          x24            rerror_rate                        % of connections that had REJ errors
          x25            srv_rerror_rate                    % of connections with REJ errors
          x26            same_srv_rate                      % of connections having the same service
          x27            diff_srv_rate                      % of connections to different services
          x28            srv_diff_host_rate                 % connections from other hosts
          x29            dst_host_count                     Number of connections to the host
                                                            established by the remote party


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          x30            dst_host_srv_count                      Number of connections to the host
                                                                 established by the remote party that use
                                                                 one service
          x31            dst_host_same_srv_rate                  % of connections to the local host
                                                                 established by the remote party using
                                                                 one service
          x32            dst_host_diff_srv_rate                  % of connections to the local host
                                                                 established by the remote party using
                                                                 different services
          x33            dst_host_same_src_port_rate             % of connections to the host at the
                                                                 current source port number
          x34            dst_host_srv_diff_host_rate             % of connections to the service of
                                                                 different hosts
          x35            dst_host_serror_rate                    % of connections with SYN error for the
                                                                 destination host
          x36            dst_host_srv_serror_rate                % of connections with SYN error for the
                                                                 receiver service
          x37            dst_host_rerror_rate                    % of connections with REJ error for the
                                                                 destination host
          x38            dst_host_srv_rerror_rate                % of connections with REJ error for the
                                                                 receiver service

   Step 4. Defining the type of membership functions to describe the ranges of values of the studied
parameters and the power of term sets for input and output linguistic variables: triangular membership
functions (2) due to the ability to undergo parametric adaptation (refinement) while maintaining an
acceptable level of computational complexity [17-22], term set power – 7 (number: VS is acronym for
“very small”, S is acronym for “small”, BA is acronym for “below average”, A is acronym for
“average”, AA is acronym for “above average”, L is acronym for “large”, VL is acronym for “very
large”).
                                                                0, x  a     
                                                           x  a             
                                                                 , a  x  b
                                                                              
                                      f   x, a, b, c    b  a            ,                     (2)
                                                               cx
                                                                  ,b  x  c 
                                                            cb              
                                                               0, x  c     
where a, b, c is a some numeric parameters that take arbitrary real values and are ordered by relations:
   a  b  c.
    Step 5. Defining input and output linguistic variables: 38 input linguistic variables that correspond
to the number of studied parameters of network traffic and one output – an indicator of the state of the
information and communications system. Each input value (𝑥 ) corresponds to the network traffic
parameter according to the KDD Cup 1999 Data, and the membership functions configured by the
expert are represented by term sets.
   x1 – {VS – very small [0, 250, 510], S –small [500, 1000, 1500], BA – below average [1400, 2000,
2500], A – average [4000, 5250, 6500], AA – above average [6400, 8500, 10500], L – large [10400,
15500, 20500], VL – very large [20000, 31000, 42500]} on the universe [0, 42500];
   x 2 – {VS – very small [0, 250, 550], S –small [520, 1000, 1500], BA – below average [1400, 5500,
10500], A – average [10000, 12500, 25500], AA – above average [25000, 40000, 54550], L – large
[2500000, 77000000, 150000000], VL – very large [120000000, 350000000, 700000000]} on the
universe [0, 700000000];


                                                                                                      97
    x 3 – {S –small [0, 500, 1000], BA – below average [1000, 5000, 9999], A – average [10000, 60000,
100000], AA – above average [125000, 600000, 1000000], L – large [1100000, 1800000, 2500000],
VL – very large [2400000, 3500000, 5250000]} on the universe [0, 5250000];
    x 4 , x9 , x11 , x12, x17 , x18 , x19 , x 24 , x 25
                                                          – {S –small [0, 0.25, 0.5], L – large [0.5, 1, 1.5]} on the universe
[0, 1.5];
    x 5 – {S –small [0, 0.25, 0.5], A – average [0.5, 1, 1.5], L – large [2.5, 3, 3.5]} on the universe [0,
3.5];
    x 6 x15 , x16 – {S –small [0, 0.25, 0.5], A – average [0.5, 1, 1.5], L – large [1.5, 2, 2.5]} on the universe
[0, 3];
    x 7 – {S –small [0, 5, 10], A – average [21, 25, 30], L – large [10, 15, 22]} on the universe [0, 30];
    x 8 – {S –small [0, 0.25, 0.5], A – average [0.5, 1, 1.5], L – large [4, 5, 6]} on the universe [0, 6];
    x10 – {S –small [0, 5, 10], L – large [15, 27.5, 40]} on the universe [0, 40];
    x13 – {S –small [0, 5, 10], A – average [10, 15, 20], L – large [30, 42.5, 55]} on the universe [0, 55];
    x14 – {S –small [0,2,5], L – large [20,22.5,25]} on the universe [0,25];




Figure 5.Graphical representation of the described linguistic terms of membership function

    x15 , x16 – {S –small [0, 50, 101], A – average [99, 200, 305], L – large [300, 400, 515]} on the
universe [0, 515];
    x 22 , x 23 , x 26 , x 27 , x 28 – {S –small [0, 0.25, 0.6], L – large [0.5, 0.8, 1.2]} on the universe [0, 1.2];
    x 29 , x 30 – {S –small [0, 50, 105], A – average [100, 150, 205], L – large [200, 230, 260]} on the
universe [0, 260];
    x 31 , x 32 , x 33 , x 34 , x 35 , x 36 , x 37 , x 38 – {S –small [0, 0.25, 0.6], L – large [0.5, 0.8, 1.2]} on the universe
[0, 1.2].

    Step 6. Preparing test data format of KDD Cup 1999 Data for the Fuzzy Logic Toolbox™ software.
    Step 7. Creating fuzzy production rules for the KB based on the KDD Cup 1999 Data set using
association rule search algorithms (Fig. 6) [23, 24].
    Step 8. Obtaining expert conclusions about the state of IP according to the classification of cyber
attacks presented in the KDD Cup 1999 Data: Denial of Service, Remote to Local, User to Root, Probe



                                                                                                                            98
and normal state: total number of rules: 335, of which Denial of Service – 68; Remote to Local – 55;
User to Root – 18; Probe – 107; Normal – 87.
   Step 9. Parametric adaptation of constructed membership functions [25, 26, 27] in order to clarify
the subjective point of view of the expert by means of the Optimization Tool package of MATLAB®
software [13, 14, 15]: on the basis of the frequent data sets found at the previous stage, parametric
optimization of membership functions was performed for the above terms of each studied variable
(search for the optimum of the parameter vector of the system of equations of the analytical model of
the triangular membership function).
   Step 10. Determining the required number of the most important (informative) parameters (features)
for each known class of cyberattacks, represented as fuzzy sets of linguistic variables that characterize
them quite fully in order to be able to identify polymorphic modifications of known cyberattacks:
   X dos  x1 , x 3 , x 5 , x 20 , x 21 , x 22 , x 23 , x 26 , x 28 , x 29 , x 30 , x 31 , x 32 , x 33 ;

   X r 2l  x1 , x 2 , x 3 , x 7 , x 9 , x 20 , x 21 , x 26 , x 28 , x 29 , x 30 , x 31 , x 32 , x 33 , x 34 , x 35 , x 36 ;

   X u 2 r   x 2 , x 3 , x 9 , x 26 , x 27 , x 29 , x 31 , x 32 , x 33 , x 37 , x 38 ;

   X probe   x 20 , x 21 , x 24 , x 25 , x 26 , x 27 , x 29 , x 30 , x 32 , x 37 , x 38 
                                                                                               .




Figure 6. Associative rules search box in Open‐Source Data Mining Library SPMF

    Step 11. Obtaining additional fuzzy production rules for KB based on the actions taken in the
previous step and removing duplicate rules. As a result, new rules were obtained in the following
quantity: Denial of Service – 48; Remote to Local – 14; User to Root – 13; Probe – 16. The total number
of rules in the KB – 426.
    Step 12. Application of the developed program code for the correct input of data from the cyberattack
data set for further analysis by the Fuzzy Logic Toolbox™ library.

Table 2.
Comparative analysis of simulation results
                                     Immune                                          Neural                  Fuzzy               Suggested
            Cyber attack class
                                     systems                                        networks                 logic                method
                   DoS                 0,98                                            1,0                    0,94                  1,0

                                                                                                                                             99
                   R2L                   0,90         0,95         0,99           0,99
                   U2L                   0,97         0,36         0,99           0,99
                  Probe                  0,96         0,99         0,90            1,0
                  Normal                 0,97         0,99         0,91           0,99
             Polymorphic (DoS)             ‐            ‐            ‐             1,0
             Polymorphic (R2l)             ‐            ‐            ‐            0,98
             Polymorphic (U2r)             ‐            ‐            ‐             1,0
            Polymorphic (Probe)            ‐            ‐            ‐            0,98

   Step 13. Conducting experimental studies on cyber attack detection by a developed simulation
model, the functioning of which is based on the application of models and methods and comparative
analysis of the results of modeling the process of detecting cyber attacks based on the proposed
approach with existing methods for detecting cyber attacks: based on the theory of fuzzy sets and fuzzy
logic, artificial immune systems and neural networks in terms of accuracy.
                                                     TD
                                      Accuracy            ,                                        (3)
                                                   TD  FN
where TD (True Detection) is the number of correctly detected cyber attacks;
FN (False Negative) is a type II errors (classifying a cyber attack as a normal state).
   A comparative analysis of the results of modeling the process of cyber attack detection based on the
approach proposed in the study and existing solutions in terms of accuracy are presented in Table 2.
   The results of the study were included in the methodology of rational choice of security incident
management system for building operational security center [28].

4. Conclusion

   The practical application of the developed simulation model of a fuzzy cyber attack detection system
showed the expediency of using it to evaluate models and methods of cyber attack detection based on
the theory of fuzzy sets and fuzzy inference. Thus, the comparison of the developed scientific and
methodological apparatus with the already available ones shows that its use makes it possible to increase
the effectiveness of information systems cyber protection in terms of the accuracy of detecting known
cyber attacks by an average of 10%, as well as to ensure the detection of polymorphic cyber attacks in
terms of accuracy of at least 98 %.

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