Pricing and Investments in Internet Security: A Cyber-Insurance Perspective

Internet users such as individuals and organizations are subject to different types of epidemic risks such as worms, viruses, spams, and botnets. To reduce the probability of risk, an Internet user generally invests in traditional security mechanisms like anti-virus and anti-spam software, sometimes also known as self-defense mechanisms. However, such software does not completely eliminate risk. Recent works have considered the problem of residual risk elimination by proposing the idea of cyber-insurance. In this regard, an important research problem is the analysis of optimal user self-defense investments and cyber-insurance contracts under the Internet environment. In this paper, we investigate two problems and their relationship: 1) analyzing optimal self-defense investments in the Internet, under optimal cyber-insurance coverage, where optimality is an insurer objective and 2) designing optimal cyber-insurance contracts for Internet users, where a contract is a (premium, coverage) pair

Bolshoi - A Modeling Spreadsheet (Improving Usability of Complex Analytical Modeling Tools)

Spreadsheet programs are very popular financial modeling tools because they allow users to juggle numbers and formulas with a powerful yet intuitive and easy to understand user interface; also, they often are equipped with sophisticated numerical analysis packages for data analysis and powerful presentation utilities for visualizing results. Computer systems performance and reliability modeling tools of today, on the other hand, have un-intuitive user interfaces and are difficult to learn and use. In this work, we propose to design, build, and evaluate Bolshoi, a modeling spreadsheet, with the goal of putting modeling tools comfortably in the hands of non-expert users. In this proposal, we address management of complexity that exists in performance and reliability analysis of real computer and communication systems. Specifically, we propose to do so through the design and development of an advanced modeling tool. Our tool will provide two important functions: (1) a proper interface for building models that will allow system designers not just to define their models, but visualize them in various ways and (2) easy plug-in of existing and future advanced solution techniques. We call this tool Bolshoi, a Modeling Spreadsheet, because it has a spreadsheet-type interface as detailed below. Performance evaluation of real systems is complex, suffers from scalability problems (or the so-called ``state explosion'' problem) and in many cases requires advanced computational techniques. Often, advanced computational techniques are based on exploitation of ``special structure'' in the models (the primary way to deal with state explosion besides getting a bigger machine). With large and complex models, these special structures are very expensive to expose automatically as it involves searching through a combinatorial number of permutations. Proper visualization of models can greatly assist in the discovery of these special structures so that state space reduction techniques can be applied. Discovery of special structure regularly contributes to many orders of magnitude in computational efficiency. Furthermore, models are often defined over infinite state spaces. We believe that a spreadsheet paradigm is ideal for visualizing such models. Without proper modeling tools, much effort and money is wasted by the computer industry, and moreover, the probability of a successful outcome is low. Thus, a good tool is crucial to advances in the state of the art in performance modeling as well as to successful design of systems in the industry. Every system designer should be able to integrate the use of a performance modeling tool into his/her design process. He/she should be able to easily ask ``what-if'' type questions, explore possible design choices, and make decisions based on quantitative results rather than ``gut feeling''. We believe that a modeling spreadsheet is the right abstraction for such tasks, and furthermore, to the best of our knowledge this abstraction has not been exploited for performance evaluation tool purposes. We believe that the approach proposed here will have a significant impact on future performance tool designs as well as make significant strides in wide-spread use of performance evaluation techniques among computer and communication system designers. Furthermore, a modeling tool that does not require expert-level methodology knowledge is also an excellent undergraduate-level and graduate-level educational tool. Opportunities for hands-on experience with modeling and performance evaluation as well as the ability to add new techniques to the tool greatly improve the educational experience of students and their future ability to apply what they have learned in class to design of real computer and communication systems. (Also cross-referenced as UMIACS-TR-2000-10

Striping Doesn't Scale: How to Achieve Scalability for Continuous Media Servers with Replication

Multimedia applications place high demands for QoS, performance, and reliability on storage servers and communication networks. These, often stringent, requirements make design of cost-effective and scalable continuous media (CM) servers difficult. In particular, the choice of data placement techniques can have a significant effect on the scalability of the CM server and its ability to utilize resources efficiently. In the recent past, a great deal of work has focused on ``wide'' data striping as a technique which ``implicitly'' solves load balancing problems; although, it does suffer from multiple shortcomings. Another approach to dealing with load imbalance problems is replication. The main focus of this paper is a study of scalability characteristics of CM servers as a function of tradeoffs between striping and replication. More specifically, striping is a good approach to load balancing while replication is a good approach to ``isolating'' nodes from being dependent on other system resources. The appropriate compromise between the degree of striping and the degree of replication is key to the design of a scalable CM server. This is the topic of our work. Also cross-referenced as UMIACS-TR-99-4

ViPEr-HiSS: A Case for Storage Design Tools

The viability of large-scale multimedia applications, depends on the performance of storage systems. Providing cost-effective access to vast amounts of video, image, audio, and text data, requires (a) proper configuration of storage hierarchies as well as (b) efficient resource management techniques at all levels of the storage hierarchy. The resulting complexities of the hardware/software co-design in turn contribute to difficulties in making accurate predictions about performance, scalability, and cost-effectiveness of a storage system. Moreover, poor decisions at design time can be costly and problematic to correct in later stages of development. Hence, measurement of systems after they have been developed is not a desirable approach to predicting their performance. What is needed is the ability to evaluate the system's design while there are still opportunities to make corrections to fundamental design flaws. In this paper we describe the framework of ViPEr-HiSS, a tool which facilitates design, development, and subsequent performance evaluation of designs of multimedia storage hierarchies by providing mechanisms for relatively easy experimentation with (a) system configurations as well as (b) application- and media-aware resource management techniques. (Also cross-referenced as UMIACS-TR-99-69

A Performance Study of Dynamic Replication Techniques in Continuous Media Servers

Multimedia applications are emerging in education, information dissemination, entertainment, as well as many other applications. The stringent requirements of such applications make design of cost-effective and scalable systems difficult, and therefore efficient adaptive and dynamic resource management techniques can be of great help in improving resource utilization and consequently improving performance and scalability of such systems. In this paper, we focus on threshold-based policies, for dynamic resource management, and specifically, in the context of continuous media (CM) servers. Furthermore, we propose a mathematical model of user behavior and show, through a performance study, that not only does the use of this model in conjunction with dynamic resource management policies improves the system's performance but that it also facilitates significantly reduced sensitivity to changes in: (a) system architecture, (b) workload characteristics, (c) skewness of data access patterns, (d) frequency of changes in data access patterns, and (e) choice of threshold values. We believe that not only is this a desirable property for a CM server, in general, but that furthermore, it suggests the usefulness of these techniques across a wide range of continuous media applications. Also cross-referenced as UMIACS-TR-98-6

On the Economic Sustainability of Cloud Sharing Systems: Are Dynamic Single Resource Sharing Markets Stable?

The recent emergence of the small cloud (SC), both in concept and in practice, has been driven mainly by issues related to service cost and complexity of commercial cloud providers (e.g., Amazon) employing massive data centers. However, the resource inelasticity problem faced by the SCs due to their relatively scarce resources might lead to a potential degradation of customer QoS and loss of revenue. A proposed solution to this problem recommends the sharing of resources between competing SCs to alleviate the resource inelasticity issues that might arise. Based on this idea, a recent effort proposed SC-Share, a performance-driven static market model for competitive small cloud environments that results in an efficient market equilibrium jointly optimizing customer QoS satisfaction and SC revenue generation. However, an important question with a non-obvious answer still remains to be answered, without which SC sharing markets may not be guaranteed to sustain in the long-run - is it still possible to achieve a stable market efficient state when the supply of SC resources is dynamic in nature? In this short paper, we take a first step to addressing the problem of efficient market design for single SC resource sharing in dynamic environments. We answer our previous question in the affirmative through the use of Arrow and Hurwicz's disequilibrium process in economics, and the gradient play technique in game theory that allows us to iteratively converge upon efficient and stable market equilibria.Peer reviewe