The Method of Allocation of the Security Functions in Neutralized Threats to Critical Information Systems

Abstract

- It is shown that the optimality of the feature sets of the protection levels of the information security system for automated systems not yet proves the optimality of these sets to neutralize threats to information security. The proposed method of adaptation of the information security system to escape threats by distributing the security functions to escape many threats on the levels of protection. Justified a hypothesis about the identity of the system evaluation criteria security threats and neutralizing their protection features. The estimates of security and threats to information security, the weighted cost of neutralizing the threats, considered the correctness of the implementation of security functions. Evaluation of the effectiveness of the security functions generated based on a cost average number of neutralized threats, preventable risk, the extent of the power of attorney and compatibility. Quantitative estimates of the values of the performance criteria represented by continuous functions. The input parameters are fixed at the time of the assessment of individual criteria of the efficiency of the security functions. Defined decision rule and the threshold of semantic preference in the allocation of security functions for neutralized threats to information security. Semantic preference threshold is used to select the functions of protection, the most effectively neutralizing the threat to levels of protection in the structure of information security system as a whole. The methodology used in the design, development and maintenance of security systems.

Keywords

• - information security
• security functions
• threats
• performance criteria
• performance evaluation
• semantic threshold preferences
• degree preference
• evaluation level
• protection level
• decision rule

INTRODUCTION

Rational sets of security features are formed using typesetting, structural and business process models of information security systems (e.g. [1-4]) and appropriately documented [5].

The optimality of the feature sets of the security levels of

the underlying system input-output, hardware, operating system, network, database management system, application software. still no evidence on the optimality of the sets of security features of these levels are involved in neutralizing specific threats.

Security functions that are distributed throughout the threats of information security needs to ensure their effective 27

STATEMENT OF THE PROBLEM

Model of information security system

Let be

MOD

 {UR},{UG},{MZ},{KR},{TR}  – a СЗИ model of the system of information protection.

Here uru  UR

– levels of protection in the system of information protection, u  1, U , U – the number of levels of protection; ugn  UG – many pressing threats to information security for critical information systems, n  1, N , N – количество актуальных угроз;

U MZ  {mzk }   MZu  {mzkKu ,u } , где MZu – a subset u 1 of the functionality of protection level of protection uru  UR , k  Ku – a subset of the indexes k  1, K security features at this level,  Ku  K ,  Ku   ;

u u krj  KR, j  1, J , many effectiveness of the security features; criteria for evaluating the trmzku  TR – many of the requirements to the security: доп доп trmzku  {rskmzku , stmmzakxu } , where rskmzku – the permissible level of risk from the threat is credible, st max – the maximum mzku allowable costs for the security function (for a class of functionally similar protection features)..

The threat to information security

ugn  { pugn , uchugn , rsk ugn  pugn  uchugn } [ 6 ], где pugn – evaluation of the possibility of a threat ugn , uchugn – the damage from realization of threats ugn , rsk ugn – the risk from implementation of threats ugn . mzku | kmKaUx poss (mzku , ugn ). mzku index k K u the selected protection level uru  UR to provide maximum ability to neutralize actual threats ugn  UG .

III.

HYPOTHESIS

A. Identity criteria

We believe that actual threats to information security are characterized by the properties inherent protection features, and evaluated on the same criteria, but choosing the worst score for neutralizing their protection features.

Potential attacks are evaluated as a whole according to the same scheme as the risk of the presence of vulnerabilities, but with some differences, for example, of several scenarios of attack is chosen by worst, with the most potential [ 7 ]. It is believed that it is a function of the level of motivation of the attacker, his skill and available resources. Motivation affects allocated to time attack and possibly attract resources and recruitment attackers.

Then, the degree of  ~ (mz ) neutralize the threat ugi

Ai k security function mz you can define as follows: k 1, если r  r ;  c н  ~ (mz )   r

Ai k  с , если если r  r  rн с н .

Here rн – the ranking of potential attacks, r - the rating с durability protection features. We believe that any threat exists, the security function such that r  r : ugi mz | r  r – с н k с н any threat neutralised at least one security feature.

IV.

PERFORMANCE CRITERIA SECURITY

FUNCTIONS

On the sets of actual threats ugn  UG and security functions mzk  MZ determined attitude MU . In the General case  MU (ugn , mzk )  [ 0,1 ] – evaluation of the possibility of neutralizing the security function mzk current threats ugn .

Evaluation of the effectiveness of the security features is going to be calculated according to the criteria presented below [ 4, 6, 8 ]. We believe that the quantitative estimation of the criteria values representable by continuous functions and monotonically vary depending on the input parameters. The input parameters are fixed at the time of the assessment of individual criteria of the efficiency of the security functions. 1) The Cost of security functions. Quantitative assessment criteria can be calculated according to the formula   b1 , 1   stmzk     a1   where 0  stmzk  stmmzaklx , a1, b1 – the configurable settings. As a parameter a1 it is recommended to select a value st max mzku – the maximum allowable costs for the protection feature.

2) The Cost of neutralizing actual threats. Denote by

mzku (kr1 ) the value of the criterion kr1 for security features mzku . Then the value ugn (kr1 ) criteria kr1 for threats ugn defined as follows: ugn (kr1 )  max { min {mzku (kr1 ) |  MU (ugn , mzku )  0}} u kKu Here min {mzku (kr1 ) |  MU (ugn , mzku )  0} – the minimum kKu value of the criterion kr for mzku , neutralizing the threat ugn 1 level uru  UR , ugn (kr1 ) – the maximum value of the neutralizing current threats and available security features. At each level of protection selected security functions with minimum cost, and to neutralize threats at all levels of system protection is considered the worst option is used – the security function with the maximum value. 1) Weighted average number of threats neutralized. Quantitative evaluation criteria for security features is going to be calculated by the formula: kr2  1

b ,   | UG | sm mzku   2 1   k     a2   where

UGk  {ugn |  MU (ugn , mzku )  0} – many threats, neutralized security function mzku ,

N sm mzku    MU (ugn , mzku ) n1 – the sum of the scores of possibilities of neutralizing the threats security function a2 , b2 –

custom settings. As a parameter a2 you must select the max (| UG | sm mzku ) – the maximum difference between the ku k number of threats and amount of estimated capabilities to neutralize threats security function mzku level u .

2) Weighted average number of protection

features, neutralizing the current threat. Quantitative evaluation criteria for threats is going to be calculated by the formula: ugn (kr2 )  min { max {mzku (kr2 ) |  MU (ugn , mzku )  0}} .

u kKu

The levels of protection selected security functions with the

maximum grade weighted average number of neutralized threats. To assess the neutralization of threats at all levels of protection considered the option of application security functions with a minimum weighted average rating number of neutralized threats. max rskmzku  max nN1 rsk ugn  (1   MU (ugn , mzku )) - the maximum risk from the implementation of threats that were not neutralized by the security function mzku on the level of protection u , and the criterion value kr3 for mzku you can define the following: доп where a3 , b3 – custom settings. Option a3  rskmzku takes the value of permissible level of risk from the threat is credible.

Assume that the actual threat neutralized at least one security feature.

2) The risk from the threat is credible. The amount

of risk from the implementation of the threats rate the following ugn (kr3 )  min { max {mzku (kr3 ) |  MU (ugn , mzku )  0}} .

u kKu The levels of protection selected security function, which can prevent maximum damage from the threat is credible. In General, the levels of protection accepted the option of causing the minimum of damage from the threat is credible. D. Power of attorney (criterion kr4 ) 1)

The level of proxy protection features. The level

security function can be determined of proxy kr4  sdmzk using the results of [ 6 ].

2) escape

The level of proxy security function against the threats is calculated as

ugn (kr4 )  min { max {mzku (kr4 ) |  MU (ugn , mzku )  0}} .

u kKu

For protection levels, a preference function of protection

with a maximum rating of degree a power of attorney. In General, the levels of protection at the neutralization of threats are characterized by the use of the least-trusted security features. mz j . The opposite may be true: mz j may not be compatible with mziu . Compatibility mzk with other security features on the criterion kr5 defined as follows: kr5 

1  1  (| SVk | smmSVzk )    a5  b5 , configurable.

2) security threats:

Assessment of the degree of compatibility of the functions in relation to neutralized

where

SVk  {mz j |  SV (mzk , mz j )  0} – many security K functions, compatible with mzk , smmSVzk  i1 SV (mzk , mzi ) – the sum of the degrees of compatibility mzi with mzk , a5 , b5 – ugn (kr5 )  min{ max {mzku (kr5 ) |  MU (ugn , mzku )  0}} .

u kKu

Levels of protection apply security function with the

maximum grade the degree of compatibility. The structure of the information security system in the neutralization of threats are characterized by the least compatible of the levels of protection.

The allocation of security functions mzku  MZ to escape

many threats to information security ugn UG associated with the choice of decision rules for such distributions.

A. The decision rule for the distribution

According to the approach [6] is required to determine the threshold of semantic preference in the allocation of security functions for neutralized threats to information security. but

The General rule is that to choose the highest value pr ,

less min i, j max mz [1  min {1,[(1   A~i (mz)) p  (1   A~j (mz)) p ] p }] .

~ ~ ~ Here, A1, A2 ,..., AN the fuzzy sets representing the degree of neutralizing of threats ugn UG , n  1, N , security function 1 mzk .

The article applied is different from [9-12] and is known

from the scientific literature alternative intersection operation 1 A A~B~ (x) 1  min {1,[(1   A~ (x)) p  (1   (x)) p ] p }, p  1 B

B. The source data

Identified a variety of protection features mzk  MZ ,

k  1, K , current threats ugn UG , n  1, N , and the criteria of efficiency krj  KR , j  1, J , security features.

1) MZ and criteria

Evaluation of security functions. On the sets

~

KR we define the relation MR –  MR~ : MZ  KR  [ 0,1 ] . For all mzk  MZ and all krj  KR  MR~ (mzk , krj ) – evaluation of security functions mzk for private performance criterion krj .

Attitude will be presented in a matrix form:

~ MR ||  MR~ (mzk , krj ) ||, k  1, K , j  1, J .

2) Assessment of security threats. Next on the set

criteria KR and current threats UG will form a relationship ~ KG –  KG~ : KR  UG  [ 0,1 ] . For all krj  KR and all ugn UG  KG~ (krj , ugn ) – threat assessment ugn according to the criterion krj determined by the necessity of neutralizing the threat ugn protection feature mzk .

In matrix form the relation takes the form ~

KG ||  MG~ (mz j , krn ) ||, j  1, J , n  1, N.

3) Weighted cost of neutralizing the threat. On the ~ ~ basis of relationships MR and KG you can form a ~ relationship MG presented below:  ug1 ug2 . . . ug N   A~ (mz1, ug1)  ~ (mz1, ug2 ) ... A~ (mz1, ug N )  mz1  1 A2 N  mz2  A~ (mz2 , ug1)  ~ (mz2 , ug2 ) ...  A~ (mz2 , ug N )   1 A2 N  .. .. .. .. .. .. .  ~ .

MG   .. . . . . . . ..  mzK  ~ (mzK , ug1)  ~ (mzK , ug2 ) ... A~ (mzK , ug N )  A1 A2 N The elements in the matrix we define as follows:

  MR~ (mz, kr)  KG~ (kr, ugn )  A~n (mz, ugn )  kr for all   MR~ (mz, kr) kr mzk  MZ , krj  KR , ugn UG .

The amount   MR~ (mz, kr) is interpreted as a number of

kr important criteria kr , characterizing the properties of mzk , and  ~ (mzk , ugn ) represents the

An weighted degree of neutralisation of actual threats ugn security function mzk .

4) The correctness of the implementation of

security functions. Previously, when determining the value  A~i (mzk ) were not made assumptions regarding the correctness of the implementation of the security functions. Now the values of criteria of efficiency of the security functions included in the computed values  ~ (mzk , ugi ) . Ai

According to the adopted approach is formed matrix W

 A~1 (mzK , ug1 )   ~ (mzK , ug 2 ),..., ~

A2 AN1 С. Semantic threshold preferences (mzK , ug N 1 )   A~ (mzK , ug N )

N

Semantic threshold preference functions on the escape

threats is determined from the condition pr  min max [1  min{1,[(1   ~ (mz)) p  (1   ~ (mz)) p ] p }], p  1

mz Ai Aj

Semantic preference threshold is used to select the

functions of protection, the most effectively neutralizing the threat ugn  UG to levels of protection in the structure of information security system as a whole. – many features of protection mzku , which can neutralize the threat ug n on the level of protection uru  UR ; M n  {mzku | max  A~n (mzku , ugn )} , u  1, U , n  1, N . Here k M n – multiple protection features, effectively neutralizing ugn most of the threat levels uru  UR of protection .

The proposed method of adaptation of the system of information security of automated systems to escape the threats used in the design, development and maintenance of security systems.

VI.

CONCLUSIONS

The optimality of the feature sets of the protection levels of the information security system for automated systems not yet proves the optimality of these sets to neutralize threats to information security.

The proposed method of distribution of the security

features on the escape threats to information security of automated systems, allowing to structure the information security system by distributing the functions of protection for many neutralized threats in information security protection levels.

Justified a hypothesis about the identity of the system evaluation criteria security threats and neutralizing their protection features.

Defined semantic threshold of preference in the allocation

of security functions for neutralized threats to information security, allowing you to select

the security function, effectively neutralizing most of the threat to levels of protection in the structure of information security system as a whole. [10] Bykov A. Yu., Gurov A. V., Problem of choice of means of protection of information from attacks in automated systems with fuzzy parameters the objective function. Engineering journal: science and innovations. Electronic scientific and technical periodical. 2012. N 1(1).

DOI: 10.18698/2308-6033-2012-1-86 [11] Andreev A. G., Kazakov G. V., Kuranov V. V. Method of assessing the strength of security functions protection of automated control system of the spacecraft mission. Engineering journal: science and innovation. Electronic scientific and technical edition. 2017. N 7(67).

DOI: 10.18698/2308-6033-2017-7-1634

The proposed method of distribution of the security features on the escape threats used in the design, development and maintenance of systems for the protection of automated systems.

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