1. University of the Aegean, Greece Modelling and Economics of IT Risk Management and Insurance Stefanos Gritzalis Costas Lambrinoudakis Dept. of Information and Communication Systems Engineering University of the Aegean - GREECE {sgritz, clam}@aegean.gr clam}@aegean.gr Thanassis Yannacopoulos Dept. of Statistics & Actuarial-Financial Mathematics University of the Aegean - GREECE ayannaco@aegean.gr

2. University of the Aegean, Greece Introduction l Information systems security has become a top priority issue for most organisations worldwide. l They have started to invest in Security Enhancing Technologies, but: l How much should they invest ? l Can they evaluate the effectiveness of the security measures that they invest on ? l Are they aware of the residual risk ? l Are they aware of the consequences that they will face in the event of a security incident ?

3. University of the Aegean, Greece AssetThreatVulnerabilityImpact Measure Calculate Risk Select Countermeasures Risk Analysis and Management

4. University of the Aegean, Greece We need better solutions l An option could be to transfer specific risks to an insurance company, in order to: –avoid implementing too expensive technical countermeasures, and –cover the financial losses that the organisation may experience in case of a security incident l Clearly, such an approach will not replace technical security measures, but it will act complementary

5. University of the Aegean, Greece Issues that must be addressed l From the Organization Point of View –How much money should be invested in technical security measures ? –Which is the financial loss that the organization will experience as a result of a security incident due to the residual risk ? l From the Insurance Company Point of View –How secure – well protected against potential risks - is the information system ? –Which is the financial loss that the organization will experience as a result of every possible security incident ? –What should the structure of the contract be (i.e. premium, compensation) ?

6. University of the Aegean, Greece Modelling the System (1/3) l Use of a probabilistic structure, in the form of a Markov model, that provides detailed information about all possible transitions of the system state in the course of time. l We are dealing with transitions from the fully operational system state to some other non- fully operational state that may result as the effect of a security incident.

7. University of the Aegean, Greece Modelling the System (2/3) –Assumption 1: The transitions allowed are from the fully operational state to some other non-fully operational state. –Assumption 2: Non-operational states are considered absorbing states.

8. University of the Aegean, Greece Modelling the System (3/3) l The use of the Markov model allows us to : –Find the probability of the system being in different states –thus find the probability of different financial losses (L) l This approach is useful in cases where: –The transition rates are accurate –The Loss (impact values) figures are accurate (objective)

9. University of the Aegean, Greece Using the Model: An Overview l OBJECTIVE 1: Calculating the Optimal Security Investment –Max I E [ U(W – L(I) – I ] l Where I is the maximum amount available for security measures l W is the initial wealth of the company and l L is the expected loss, that of course depends on the amount I l OBJECTIVE 2: Designing the Optimal Insurance Contract –U(W – π) = Ε [ U(W – L + C – π)] l Where W is the initial wealth of the company l π is the premium that the company has to pay to the insurer l L is the expected loss l C is the compensation that the insurer will pay in case of a security incident

10. University of the Aegean, Greece OBJECTIVE 1: Calculating the Optimal Security Investment (1/3) l How much should a company invest in security? l Given a security budget, how should this be allocated with respect to the different risks so as to minimize the expected loss of the company?

11. University of the Aegean, Greece An Illustrative Example (2/3) l Assume two Threats of equal probability to occur and equally harmful l Assume that we invest z i for security measures that address Threat I, i=1,2 l It can be noticed that the optimal choice is z 1 =z 2 z2z2 z1z1

12. University of the Aegean, Greece An Illustrative Example (3/3) l Assume two Threats equally harmful l Assume that the first Threats is more likely to occur l Assume that we invest z i for security measures that address Threat I, i=1,2 l It can be noticed that the optimal budget allocates more expenditure towards the facing of the first threat z1z1 z2z2

13. University of the Aegean, Greece OBJECTIVE 2: Design the Optimal Insurance Contract (1/7) l Following the investment of an amount of money for security measures, the company still needs to deal with the residual risk. l An option could be to divert the risk into an alternative market: An Insurance Company l The model presented may support us in designing and pricing insurance contracts

14. University of the Aegean, Greece A Case Study (2/7) l Suppose a firm A subcontracts specific IT tasks to a firm B l Unfortunately A cannot be aware of Bs intentions (e.g. B may disclose data in an unauthorized way, for profit) l Can A and B enter into an insurance contract through an insurer I so that all three parties are better off with the contract than without?

15. University of the Aegean, Greece A Case Study (3/7) l ν: Probability that B plays fair l d: Probability that the fraud passes undiscovered l p1: Given that B plays fair, probability of no security incident at all l p2: Given that B plays fair, probability of a security incident due to unforeseen circumstances or due to negligence of A

16. University of the Aegean, Greece A Case Study (4/7)

17. University of the Aegean, Greece Premium for A (5/7) l Premium Maximum Value (1) when: l d = 1 and ν = 0 (B acts maliciously and the fraud will not be discovered) l Premium Minimum Value when: l ν = 1 and d = 0 (B is reliable and in case it commits a fraud it will be discovered)

18. University of the Aegean, Greece Premium for B (6/7) l The introduction of the fine (F) lowers considerably the premium for B. l The fine plays the role of compensation to the insurer in case of deliberate fraudulent behavior and as such reduces the risk of the insurer

19. University of the Aegean, Greece Optimal coverage for A and utility difference (7/7)

20. University of the Aegean, Greece Future Directions We are currently thinking of ways to cope with: –Non-absorbing states –Approximate transition rates –Subjective figures for the Loss (An indicative example is Privacy Violation) –More complex models that in order to calculate the transition probability of the system to a different state take into account the full history of transitions –Use of real data for Model Calibration

21. University of the Aegean, Greece Thank you for your attention.. http://www.aegean.gr/Info-Sec-Lab/