Nowadays, both the amount of cyberattacks and their sophistication have considerably increased, and their prevention is of concern of most of organizations. Cooperation by means of information sharing is a promising strategy to address this problem, but unfortunately it poses many challenges. Indeed, looking for a win-win environment is not straightforward and organizations are not properly motivated to share information. This work presents a model to analyse the benefits and drawbacks of information sharing among organizations that presents a certain level of dependency. The proposed model applies functional dependency network analysis to emulate attacks propagation and game theory for information sharing management. We present a simulation framework implementing the model that allows for testing different sharing strategies under several network and attack settings. Experiments using simulated environments show how the proposed model provides insights on which conditions and scenarios are beneficial for information sharing.
@cite_11 use game theory to help organizations to decide whether to share information or not, using the CYBEX framework @cite_7 . Authors use evolutionary game theory in order to attain an evolutionary stable strategy (ESS) under various conditions. These conditions are extracted through simulation with synthetic data in a non-cooperative scenario with rational and profit-seeking firms. The main incentive for sharing is the information received, and thus the knowledge gained. In our work we also consider this knowledge as an incentive for sharing. @cite_12 present a two stage Bayesian game between two firms to help to decide how much to invest in searching vulnerabilities and how much of this information to share. Authors determine the Perfect Bayesian Equilibrium to extract analytically strategy conditions encouraging information sharing. In @cite_12 a firm benefits from losses in another, namely due to exploited bugs. Moreover, they distinguished costs between: direct loss (of compromised firm), common loss by market shrinkage and competitive loss.
@cite_12 @cite_7 @cite_11
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Sharing of security information among organizations has often been proposed as a method for improving the state of cyber-security for all. However, such disclosure entails costs for the reporting entity, including a drop in market value, loss of customer confidence, and bureaucratic burdens. By adopting a game-theoretic approach for understanding firms' incentives, we first show that in one shot interactions, disclosure costs act as disincentives for sharing, leading to no information sharing at equilibrium. We then consider a repeated game formulation that enables the use of inter-temporal incentives (i.e., the conditioning of future decisions on the history of past interactions) to support firms' cooperation on information sharing. We show that the nature of the monitoring available to firms greatly affects the possibility of sustaining nearly efficient outcomes through repeated interactions. Specifically, we first illustrate the limitations arising when firms' have independent and imperfect private monitoring technologies. We then consider the role of a public monitoring assessment system, and show that despite using the same imperfect technology as the individual firms, the monitor can facilitate cooperation among participants. Our results therefore illustrate the impact of a public rating reputation system on the viability of security information sharing agreements. Part I of this paper has described a new theory for the analysis of games with incomplete information. It has been shown that, if the various players' subjective probability distributions satisfy a certain mutual-consistency requirement, then any given game with incomplete information will be equivalent to a certain game with complete information, called the “Bayes-equivalent” of the original game, or briefly a “Bayesian game.” Part II of the paper will now show that any Nash equilibrium point of this Bayesian game yields a “Bayesian equilibrium point” for the original game and conversely. This result will then be illustrated by numerical examples, representing two-person zero-sum games with incomplete information. We shall also show how our theory enables us to analyze the problem of exploiting the opponent's erroneous beliefs. However, apart from its indubitable usefulness in locating Bayesian equilibrium points, we shall show it on a numerical example the Bayes-equivalent of a two-person cooperative game that the normal form of a Bayesian game is in many cases a highly unsatisfactory representation of the game situation and has to be replaced by other representations e.g., by the semi-normal form. We shall argue that this rather unexpected result is due to the fact that Bayesian games must be interpreted as games with “delayed commitment” whereas the normal-form representation always envisages a game with “immediate commitment.” We study competition between wireless devices with incomplete information about their opponents. We model such interactions as Bayesian interference games. Each wireless device selects a power profile over the entire available bandwidth to maximize its data rate. Such competitive models represent situations in which several wireless devices share spectrum without any central authority or coordinated protocol. In contrast to games where devices have complete information about their opponents, we consider scenarios where the devices are unaware of the interference they cause to other devices. Such games, which are modeled as Bayesian games, can exhibit significantly different equilibria. We first consider a simple scenario of simultaneous move games, where we show that the unique Bayes-Nash equilibrium is where both devices spread their power equally across the entire bandwidth. We then extend this model to a two-tiered spectrum sharing case where users act sequentially. Here one of the devices, called the primary user, is the owner of the spectrum and it selects its power profile first. The second device (called the secondary user) then responds by choosing a power profile to maximize its Shannon capacity. In such sequential move games, we show that there exist equilibria in which the primary user obtains a higher data rate by using only a part of the bandwidth. In a repeated Bayesian interference game, we show the existence of reputation effects: an informed primary user can bluff to prevent spectrum usage by a secondary user who suffers from lack of information about the channel gains. The resulting equilibrium can be highly inefficient, suggesting that competitive spectrum sharing is highly suboptimal. We study a setting where a set of players simultaneously invest in a shared resource. The resource has a probability of failure and a return on investment, both of which are functions of the total investment by all players. We use a simple reference dependent preference model to capture players with heterogeneous risk attitudes (risk seeking, risk neutral and risk averse). We show the existence and uniqueness of a pure strategy Nash equilibrium in this setting and examine the effect of different risk attitudes on players' strategies in the presence of uncertainty. In particular, we show that at the equilibrium, risk averse players are pushed out of the resource by risk seeking players. We compare the failure probabilities in the decentralized (game-theoretic) and centralized settings, and show that our proposed game belongs to the class of best response potential games, for which there are simple dynamics that allow all players to converge to the equilibrium.