TY - CONF AU - Wex, Felix AU - Schryen, Guido AU - Neumann, Dirk ID - 5576 T2 - Proceedings of the 46th Hawaii International Conference on System Science TI - Decision Modeling for Assignments of Collaborative Rescue Units during Emergency Response ER - TY - JOUR AU - Schryen, Guido ID - 5637 IS - 2 JF - European Journal of Information Systems (EJIS) TI - Revisiting IS Business Value Research: What we already know, what we still need to know, and how we can get there VL - 22 ER - TY - CONF AU - Püschel, Tim AU - Schryen, Guido AU - Hristova, Diana AU - Neumann, Dirk ID - 5680 T2 - European Conference on Information Systems TI - Cloud Service Revenue Management ER - TY - CONF AU - Lang, Fabian AU - Schryen, Guido AU - Fink, Andreas ID - 5683 T2 - International Conference on Information Systems TI - Elicitating, modeling, and processing uncertain human preferences for software agents in electronic negotiations: An empirical study ER - TY - JOUR AU - Bodenstein, Christian AU - Schryen, Guido AU - Neumann, Dirk ID - 5688 IS - 1 JF - European Journal of Operational Research : EJOR TI - Energy-Aware Workload Management Models for Operating Cost Reduction in Data Centers VL - 222 ER - TY - JOUR AU - Wex, Felix AU - Schryen, Guido AU - Neumann, Dirk ID - 5578 IS - 3 JF - International Journal of Information Systems for Crisis Response and Management TI - A Fuzzy Decision Support Model for Natural Disaster Response under Informational Uncertainty VL - 4 ER - TY - CONF AU - Wex, Felix AU - Schryen, Guido AU - Neumann, Dirk ID - 5579 T2 - International Conference on Information Systems for Crisis Response and Management (ISCRAM) 2012 TI - Operational Emergency Response under Informational Uncertainty: A Fuzzy Optimization Model for Scheduling and Allocating Rescue Units ER - TY - CONF AU - Schryen, Guido AU - Wex, Felix ID - 5615 T2 - 45th Hawaii International Conference on System Sciences TI - IS Design Thinking in Disaster Management Research ER - TY - JOUR AU - Schryen, Guido ID - 5638 JF - Die Zeit TI - Profis im Netz: Soziale Netzwerke könnten in Unternehmen viel mehr Nutzen stiften - woran hakt es?, in: Die Zeit (12.04.2012) ER - TY - JOUR AU - Schryen, Guido ID - 5639 JF - IM Information Management & Consulting TI - Soziale Netzwerke in Unternehmenskontexten - Potentiale und Anforderungen, in: Information Management & Consulting, to appear ER - TY - CONF AU - Lang, Fabian AU - Schryen, Guido AU - Fink, Andreas ID - 5684 T2 - Proceedings of the 2011 International Conference on Information Systems (ICIS 2011) TI - Automated Negotiations Under Uncertain Preferences ER - TY - CONF AU - Bodenstein, Christian AU - Schryen, Guido AU - Neumann, Dirk ID - 5689 T2 - Proceedings of the 19th European Conference on Information Systems (ECIS 2011) TI - Reducing Datacenter Energy Usage through Efficient Job Allocation ER - TY - CONF AU - Wex, Felix AU - Schryen, Guido AU - Neumann, Dirk ID - 5581 T2 - Proceedings of the 8th International Conference on Information Systems for Crisis Response and Management (ISCRAM 2011) TI - Intelligent Decision Support for Centralized Coordination during Emergency Response ER - TY - CONF AU - Schryen, Guido AU - Volkamer, Melanie AU - Ries, Sebastian ID - 5619 T2 - Proceedings of the 26th Annual ACM Symposium on Applied Computing TI - A formal approach towards measuring trust in distributed systems ER - TY - JOUR AU - Schryen, Guido ID - 5640 IS - No. 5 JF - Communications of the ACM (CACM) TI - Is open source security a myth? What do vulnerability and patch data say? VL - Vol. 54 ER - TY - CONF AU - Schryen, Guido ID - 5641 T2 - IS Capabilities Change, and IS Innovation, Proceedings of the 19th European Conference on Information Systems (ECIS 2011), Helsinki TI - Seeking the VALUE in IS Business Value Research - An Agenda for investigating Synergies Between Socio-organizational Change, IS Capabilities Change, and IS Innovation ER - TY - CONF AB - In double-sided markets for computing resources an optimal allocation schedule among job offers and requests subject to relevant capacity constraints can be determined. With increasing storage demands and emerging storage services the question how to schedule storage jobs becomes more and more interesting. Since such scheduling problems are often in the class NP-complete an exact computation is not feasible in practice. On the other hand an approximation to the optimal solution can easily be found by means of using heuristics. The problem with this attempt is that the suggested solution may not be exactly optimal and is thus less satisfying. Considering the two above mentioned solution approaches one can clearly find a trade-off between the optimality of the solution and the efficiency to get to a solution at all. This work proposes to apply and combine heuristics in optimization to gain from both of their benefits while reducing the problematic aspects. Following this method it is assumed to get closer to the optimal solution in a shorter time compared to a full optimization. AU - Finkbeiner, Josef AU - Bodenstein, Christian AU - Schryen, Guido AU - Neumann, Dirk ID - 5685 KW - Decision Support System KW - Algorithms KW - Optimization KW - Market Engineering T2 - 18th European Conference on Information Systems (ECIS 2010) TI - Applying heuristic methods for job scheduling in storage markets ER - TY - CONF AB - In a world, where more and more businesses seem to trade in an online market, the supply of online services to supply the ever-growing demand could quickly reach its capacity limits. Online service providers may find themselves maxed out at peak operation levels during high-traffic timeslots but too little demand during low-traffic timeslots, although the latter is becoming less frequent. At this point not only deciding which user is allocated what level of service becomes essential, but also the magnitude of the service provided, can be controlled by pricing. Pricing is an important factor when efficient and acceptable allocation of resources between individuals must be reached. Without prices, transferring or sharing goods would be impossible. In sharing information, pricing a product however is not as simple as relatively pricing an apple or a pear. Often the costs, and hence the prices are simply unknown. Backed by this scenario, the online services market could be combined with the market design mechanism of diamonds. For this we propose an ultimatum pricing strategy which effectively allows for valuations to be accounted for, but no longer a necessity when pricing in grid, cloud or other online computing environments. AU - Bodenstein, Christian AU - Schryen, Guido AU - Neumann, Dirk ID - 5690 KW - Posted Price KW - Ultimatum Game KW - Energy Efficiency KW - Mechanism Design T2 - 18th European Conference on Information Systems (ECIS 2010) TI - From "Take-it-or-leave-it" offers to "Take-it-or-be-left-out" Ultimatum - A trade mechanism for Online Services ER - TY - CONF AB - Emerging digital environments and infrastructures, such as distributed services and computing services, have generated new options of communication, information sharing, and resource utilization in past years. Different distributed trust concepts are applied to increase trust in such systems. However, these concepts yield to rather complex architectures which make it difficult to determine which component or system needs to be trusted. This paper presents a novel trust measurement method for distributed systems which enables the t identification of weak points in the overall system architecture. The measurement method includes the specification of a formal trust language and its representation by means of propositional logic formulas. The applicability of the proposed concepts is demonstrated by conducting a case study on the Internet voting system that was used in the 2007 parliamentary elections in Estonia. AU - Volkamer, Melanie AU - Schryen, Guido ID - 5598 KW - distributed trust concepts KW - measuring etrust KW - Internet voting T2 - Proceedings of the 23rd Bled eConference TI - Measuring eTrust in distributed systems - General Concept and Application to Internet Voting ER - TY - CONF AB - While many theoretical arguments against or in favor of open source and closed source software development have been presented, the empirical basis for the assessment of arguments and the development of models is still weak. Addressing this research gap, this paper presents the first comprehensive empirical investigation of published vulnerabilities and patches of 17 widely deployed open source and closed source software packages, including operating systems, database systems, web browsers, email clients, and office systems. The empirical analysis uses comprehensive vulnerability data contained in the NIST National Vulnerability Database and a newly compiled data set of vulnerability patches. The results suggest that it is not the particular software development style that determines the severity of vulnerabilities and vendors? patching behavior, but rather the specific application type and the policy of the particular development community, respectively. AU - Schryen, Guido AU - Eliot, Rich ID - 5631 T2 - 43rd Annual Hawaii International Conference on System Sciences TI - Increasing software security through open source or closed source development? Empirics suggest that we have asked the wrong question ER - TY - CONF AB - Enduring doubts about the value of IS investments reveal that IS researchers have not fully managed to identify and to explain the economic benefits of IS. Three research tasks are essential requisites on the path towards addressing this criticism: the synthesis of knowledge, the identification of lack of knowledge, and the proposition of paths for closing knowledge gaps. This paper considers each of these tasks by a) synthesizing key research findings based on a comprehensive literature review, b) identifying and unfolding key limitations of current research, and c) applying a decision-theoretic perspective, which opens new horizons to IS business value research and shows paths for overcoming the limitations. The adoption of this perspective results in a decision-theoretic foundation of IS business value research and includes the proposition of a consistent terminology and a research model that frames further research. AU - Schryen, Guido AU - Bodenstein, Christian ID - 5632 KW - Decision theory KW - IT value KW - IS assessment KW - IS evaluation T2 - Proceedings of the 18th European Conference on Information Systems (ECIS 2010) TI - A decision-theoretic foundation of IS business value research ER - TY - CONF AB - This paper presents a fuzzy set based decision support model for taking uncertainty into account when making security investment decisions for distributed systems. The proposed model is complementary to robabilistic approaches and useful in situations where probabilistic information is either unavailable or not appropriate to reliably predict future conditions. We ?rst present the speci?cation of a formal security language that allows to specify under which conditions a distributed system is protected against security violations. We show that each term of the security language can be transformed into an equivalent propositional logic term. Then we use propositional logic terms to de?ne a fuzzy set based decision model. This optimization model incorporates uncertainty with regard to the impact of investments on the achieved security levels of components of the distributed system. The model also accounts for budget and security constraints, in order to be applicable in practice. AU - Schryen, Guido ED - C. Freiling, Felix ID - 5642 T2 - Sicherheit 2010 : Sicherheit, Schutz und Zuverl{\"a}ssigkeit ; Konferenzband der 5. Jahrestagung des Fachbereichs Sicherheit der Gesellschaft f{\"u}r Informatik e.V. (GI), 5. - 7. Oktober 2010 in Berlin TI - A Fuzzy Model for IT Security Investments VL - 170 ER - TY - CONF AB - Enduring doubts about the value of IS investments reveal that IS researchers have not fully managed to identify and to explain the economic benefits of IS. This paper assumes that literature reviews, which represent a powerful instrument for the identification and synthesis of knowledge, have not tapped their full potential to address this issue due to deficiencies in methodology. The analysis of 18 literature reviews published in pertinent academic outlets during the past 20 years shows such deficiencies. Two of the most critical weaknesses identified are (1) the lack of theory use in most reviews and (2) a weak linkage of reviews, resulting in little progress in theory and framework development. The systematic identification of these weaknesses and the extraction of promising methodological examples from past literature are the main contributions of this work, which supports the composition of more effective literature reviews in future research. AU - Schryen, Guido ID - 5643 KW - Literature review KW - Business value KW - Information systems KW - Methodology KW - Theory T2 - Proceedings of the First Scandinavian Conference on Information Systems (SCIS) TI - An Analysis of Literature Reviews on IS Business Value: How Deficiencies in Methodology and Theory Use Resulted in Limited Effectiveness ER - TY - JOUR AB - The economic relevance of information systems has been studied for many years and has attracted an abundance of research papers. However, the ?productivity paradoxon? of the 90s, Carr?s widely recognized paper ?IT doesn?t matter?, and several studies that do not find a positive correlation between IS investments and economic performance reveal long-lasting difficulties for IS researchers to explain ?IS business value?. Business executives and researchers also continue to question the value of IS investments. This raises the question of whether literature reviews have tapped their potential to address the concerns by covering key research areas of IS business value and preserving their key findings. In order to address this question, this paper identifies and describes 12 key research areas, and synthesizes what literature reviews published in pertinent academic outlets have done to preserve knowledge. The analysis of 22 literature reviews shows that some crucial areas have not been (sufficiently) covered. They provide fertile areas for future literature reviews. As this work is based on the results of more than 200 research papers, it is capable of drawing a comprehensive picture of the current state-of-the-art in IS business value research. AU - Schryen, Guido ID - 5644 IS - 4 JF - Business \& Information Systems Engineering (BISE) KW - Business value KW - Information systems KW - Literature review KW - Meta review TI - Preserving knowledge on IS business value: what literature reviews have done VL - 52 ER - TY - JOUR AB - The economic relevance of information systems has been studied for many years and has attracted an abundance of research papers. However, the ?productivity paradoxon? of the 1990s, Carr?s widely recognized paper ?IT doesn?t matter?, and several studies that do not find a positive correlation between IS investments and economic performance reveal long-lasting difficulties for IS researchers to explain ?IS business value?. Business executives and researchers also continue to question the value of IS investments. This raises the question of whether literature reviews have tapped their potential to address the concerns by covering key research areas of IS business value and preserving their key findings. In order to address this question, this paper identifies and describes 12 key research areas, and synthesizes what literature reviews published in pertinent academic outlets have done to preserve knowledge. The analysis of 22 literature reviews shows that some crucial areas have not been (sufficiently) covered. They provide fertile areas for future literature reviews. As this work is based on the results of more than 200 research papers, it is capable of drawing a comprehensive picture of the current state-of-the-art in IS business value research. AU - Schryen, Guido ID - 5645 IS - 4 JF - Wirtschaftsinformatik TI - Ökonomischer Wert von Informationssystemen - Beitrag von Literatur-Reviews zum Wissenserhalt ( = Preserving Knowledge on IS Business Value. What Literature Reviews Have Done) VL - 52 ER - TY - CONF AB - Der Beitrag diskutiert die kontroversen Ans{\"a}tze ? Verifizierung versus Evaluation/Zertifizierung ? zur Sicherung elektronischer Wahlen mit Wahlger{\"a}ten. Dabei spielt das Urteils des Bundesverfassungsgerichts [BVG099] eine zentrale Rolle. Hierin wird entschieden, dass die Zertifizierung des Wahlger{\"a}tes nicht ausreicht und es werden Verifizierungsfunktionen gefordert, die den W{\"a}hlern die M{\"o}glichkeit geben sich von der Integrit{\"a}t des Wahlergebnisses zu {\"u}berzeugen. Der Beitrag zeigt auf, dass auch mit der Implementierung entsprechender Verifizierungsfunktionen nicht auf Zertifizierung verzichtet werden kann, da an ein Wahlger{\"a}t auch andere Anforderungen wie etwa hinsichtlich des Wahlgeheimnisses gestellt werden. Es wird au{\ss}erdem die Frage diskutiert, warum der Zertifizierung hinsichtlich dieser zus{\"a}tzlichen Anforderungen vertraut werden kann, w{\"a}hrend dies nicht der Fall bei der Integrit{\"a}tsanforderung ist. AU - Volkamer, Melanie AU - Schryen, Guido AU - Langer, Lucie AU - Schmidt, Axel AU - Buchmann, Johannes ID - 5597 T2 - Workshop Elektronische Wahlen, elektronische Teilhabe, Societyware, 39th GI-Jahrestagung TI - Elektronische Wahlen: Verifizierung vs. Zertifizierung ER - TY - JOUR AB - Remote voting through the Internet provides convenience and access to the electorate. At the same time, the security concerns facing any distributed application are magnified when the task is so crucial to democratic society. In addition, some of the electoral process loses transparency when it is encapsulated in information technology. In this paper, we examine the public record of three recent elections that used Internet voting. Our specific goal is to identify any potential flaws that security experts would recognize, but may have not been identified in the rush to implement technology. To do this, we present a multiple exploratory case study, looking at elections conducted between 2006 and 2007 in Estonia, Netherlands, and Switzerland. These elections were selected as particularly interesting and accessible, and each presents its own technical and security challenges. The electoral environment, technical design and process for each election are described, including reconstruction of details which are implied but not specified within the source material. We found that all three elections warrant significant concern about voter security, verifiability, and transparency. Usability, our fourth area of focus, seems to have been well-addressed in these elections. While our analysis is based on public documents and previously published reports, and therefore lacking access to any confidential materials held by electoral officials, this comparative analysis provides interesting insight and consistent questions across all these cases. Effective review of Internet voting requires an aggressive stance towards identifying potential security and operational flaws, and we encourage the use of third party reviews with critical technology skills during design, programming, and voting to reduce the changes of failure or fraud that would undermine public confidence. AU - Schryen, Guido AU - Rich, Eliot ID - 5621 IS - 4 Part JF - IEEE Transactions on Information Forensics \& Security KW - e-voting KW - Internet voting KW - Internet election KW - security KW - verifiability KW - RIES KW - Estonia KW - Neuch{\^a}tel TI - Security in Large-Scale Internet Elections: A Retrospective Analysis of Elections in Estonia, The Netherlands, and Switzerland VL - 4 ER - TY - CONF AB - The increasing availability and deployment of open source software in personal and commercial environments makes open source software highly appealing for hackers, and others who are interested in exploiting software vulnerabilities. This deployment has resulted in a debate ?full of religion? on the security of open source software compared to that of closed source software. However, beyond such arguments, only little quantitative analysis on this research issue has taken place. We discuss the state-of-the-art of the security debate and identify shortcomings. Based on these, we propose new metrics, which allows to answer the question to what extent the review process of open source and closed source development has helped to fix vulnerabilities. We illustrate the application of some of these metrics in a case study on OpenOffice (open source software) vs. Microsoft Office (closed source software). AU - Schryen, Guido AU - Kadura, Rouven ID - 5625 KW - Open source software KW - Closed source software KW - Security KW - Metrics T2 - 24th Annual ACM Symposium on Applied Computing TI - Open Source vs. Closed Source Software: Towards Measuring Security ER - TY - CONF AB - While many theoretical arguments against or in favor of open source and closed source software development have been presented, the empirical basis for the assessment of arguments is still weak. Addressing this research gap, this paper presents a comprehensive empirical investigation of the patching behavior of software vendors/communities of widely deployed open source and closed source software packages, including operating systems, database systems, web browsers, email clients, and office systems. As the value of any empirical study relies on the quality of data available, this paper also discusses in detail data issues, explains to what extent the empirical analysis can be based on vulnerability data contained in the NIST National Vulnerability Database, and shows how data on vulnerability patches was collected by the author to support this study. The results of the analysis suggest that it is not the particular software development style that determines patching behavior, but rather the policy of the particular software vendor. AU - Schryen, Guido ID - 5646 T2 - 5th International Conference on IT Security Incident Management \& IT Forensics TI - A comprehensive and comparative analysis of the patching behavior of open source and closed source software vendors ER - TY - CONF AB - Reviewing literature on open source and closed source security reveals that the discussion is often determined by biased attitudes toward one of these development styles. The discussion specifically lacks appropriate metrics, methodology and hard data. This paper contributes to solving this problem by analyzing and comparing published vulnerabilities of eight open source software and nine closed source software packages, all of which are widely deployed. Thereby, it provides an extensive empirical analysis of vulnerabilities in terms of mean time between vulnerability disclosures, the development of disclosure over time, and the severity of vulnerabilities, and allows for validating models provided in the literature. The investigation reveals that (a) the mean time between vulnerability disclosures was lower for open source software in half of the cases, while the other cases show no differences, (b) in contrast to literature assumption, 14 out of 17 software packages showed a significant linear or piecewise linear correlation between time and the number of published vulnerabilities, and (c) regarding the severity of vulnerabilities, no significant differences were found between open source and closed source. AU - Schryen, Guido ID - 5647 KW - Vulnerabilities KW - security KW - open source software KW - closed source software KW - empirical comparison T2 - 15th Americas Conference on Information Systems TI - Security of open source and closed source software: An empirical comparison of published vulnerabilities ER - TY - JOUR AU - Schryen, Guido ID - 5648 IS - 7 JF - Linux Technical Review TI - Effektivität und Effizienz von Anti-Spam-Maßnahmen ER - TY - CONF AB - The Estonian parliamentary election in 2007 is regarded as a success story of large-scale Internet elections. I use this election in a single case study on practical security to show that low quality of security and its management does not necessarily prevent large-scale Internet elections from being conducted. I also provide research propositions with regard to future challenges for large-scale Internet elections. AU - Schryen, Guido ID - 5649 KW - Internet voting KW - large-scale election KW - Estonian parliamen- tary election KW - security KW - security management T2 - 7th Workshop on e-Business (WEB 2008, AIS Special Interest Group on E-Business) TI - Practical Security of Large-scale Elections: An Exploratory Case Study of Internet Voting in Estonia ER - TY - GEN AB - Spamming remains a form of Internet abuse, which burdens the Internet infrastructure, is generally regarded as an annoyance, and is said to cause a huge economic harm. Many technological, organizational, and legislative anti-spam measures have already been proposed and implemented, but have not led to any substantial decrease in the number of spam e-mails. We propose a scalable and flexible infrastructure framework that integrates several anti-spam measures and that features both a technological and an organizational facet. The key element of our infrastructure is a new organizational unit that reliably and transparently limits the number of e-mails that can be sent per day and per account. We also analyze the proposed framework in terms of its theoretical effectiveness, the required resources, and its limitations. AU - Schryen, Guido ID - 6287 KW - Email KW - Infrastructure KW - Internet KW - Spam TI - Preventing E-mail Spam: The Conceptualization and the Analysis of an Infrastructure Framework ER - TY - CHAP AU - Schryen, Guido ED - Satesh, D. ED - Prabhakar, R. ID - 5650 T2 - Proceedings of IPSI International Conference on Advances in the Internet, Processing, Systems, and Interdisciplinary Research TI - A Scalable and Flexible Infrastructure Framework For Addressing Spam ER - TY - BOOK AU - Schryen, Guido ID - 5651 TI - Anti-Spam Measures: Analysis and Design ER - TY - JOUR AB - More than half of world-wide e-mail traffic ? an estimated total of several billion e-mails per day ? consists of spam. This is becoming a considerable disturbance to telecommunications. Spam is also closely related to other kinds of cyber crime as it possibly contains malicious software or is pursuing some kind of fraudulent aim, such as phishing. Besides technical and organizational measures, many countries have introduced anti-spam legislation. However, today's world-wide legislative coverage of spam is heterogeneous, and its effectiveness is controversially discussed. This article describes important parameters by which anti-spam legislation can vary and gives an overview and analysis of world-wide anti-spam legislation, including the European Directive 2002/58/EC, the U.S. CANSPAM Act of 2003, and international cooperation, such as the London Action Plan. The article then proceeds to discuss the effectiveness of current laws, and it identifies problems resulting from the fact that an international phenomenon is being addressed by national legislation. Finally, the article presents suggestions for overcoming some of these problems. AU - Schryen, Guido ID - 5652 IS - 1 JF - Information and Communications Technology Law TI - Anti-spam legislation: An analysis of laws and their effectiveness VL - 16 ER - TY - CHAP AU - Schryen, Guido ED - Satesh, D. ED - Prabhakar, R. ID - 5653 T2 - Spam: An Introduction TI - Approaches Addressing Spam ER - TY - CONF AB - Spamming remains a form of Internet abuse, which burdens the Internet infrastructure, is generally regarded as an annoyance, and is said to cause economic harm to the tune of about several billion US\$ per year. Many technological, organizational, and legislative anti-spam measures have already been proposed and implemented, but have not led to any substantial decrease in the number of spam e-mails. We propose here a new infrastructure framework that combines several anti-spam measures in a framework that features both a technological and an organizational facet. The key element of our infrastructure is a new organizational unit that reliably and transparently limits he number of e-mails that can be sent per day and per account. This paper first gives an overview of the framework, then it provides technological and organizational details of the infrastructure, the deployment of which depends to a large degree on its acceptance and propagation by the ICANN, the ISOC, and by large e-mail service providers. Finally, the paper discusses the limitations and drawbacks of the proposed framework. AU - Schryen, Guido ID - 5654 T2 - 40th Annual Hawaii International Conference on System Sciences TI - Armed for the spam battle - a technological and organizational infrastructure framework ER - TY - JOUR AB - Spam e-mails have become a serious technological and economic problem. Up to now, by deploying complementary anti-spam measures, we have been reasonably able to withstand spam e-mails and use the Internet for regular communication. However, if we are to avert the danger of losing the Internet e-mail service in its capacity as a valuable, free and worldwide medium of open communication, anti-spam activities should be performed more systematically than is currently the case regarding the mainly heuristic, anti-spam measures in place. A formal framework, within which the existing delivery routes that a spam e-mail may take, and anti-spam measures and their effectiveness can be investigated, will perhaps encourage a shift in methodology and pave the way for new, holistic anti-spam measures. This paper presents a model of the Internet e-mail infrastructure as a directed graph and a deterministic finite automaton and draws on automata theory to formally derive the spam delivery routes. The most important anti-spam measures are then described. Methods controlling only specific delivery routes are evaluated in terms of how effectively they cover the modeled e-mail infrastructure; methods operating independently of any particular routes receive a more general assessment. AU - Schryen, Guido ID - 5655 IS - 2 JF - The Journal of Information Systems Security (AIS Special Interest Group in Security) KW - e-mail KW - spam KW - e-mail infrastructure KW - anti-spam measures KW - spamming options TI - Do anti-spam measures effectively cover the e-mail communication network? A formal approach VL - 3 ER - TY - CHAP AU - Schryen, Guido ED - Schulte, Heinz ID - 5656 T2 - Vom LAN zum Kommunikationsnetz - Systeme und Applikationen TI - Location Based Services ER - TY - CHAP AU - Schryen, Guido ED - Schulte, Heinz ID - 5657 T2 - Vom LAN zum Kommunikationsnetz - Systeme und Applikationen, Edition 02/2007 TI - Spam-Emails VL - 9/12 ER - TY - JOUR AB - Email communication is encumbered with a mass of email messages which their recipients have neither requested nor require. Even worse, the impacts of these messages are far from being simply an annoyance, as they also involve economic damage. This manuscript examines the resource ?email addresses?, which is vital for any potential bulk mailer and spammer. Both a methodology and a honeypot conceptualization for implementing an empirical analysis of the usage of email addresses placed on the Internet are proposed here. Their objective is to assess, on a quantitative basis, the extent of the current harassment and its development over time. This ?framework? is intended to be extensible to measuring the effectiveness of address-obscuring techniques. The implementation of a pilot honeypot is described, which led to key findings, some of them being: (1) Web placements attract more than two-thirds (70\%) of all honeypot spam emails, followed by newsgroup placements (28.6\%) and newsletter subscriptions (1.4\%), (2) the proportions of spam relating to the email addresses? top-level domain can be statistically assumed to be uniformly distributed, (3) More than 43\% of addresses on the web have been abused, whereas about 27\% was the case for addresses on newsgroups and only about 4\% was the case for addresses used for a newsletter subscription, (4) Regarding the development of email addresses? attractiveness for spammers over time, the service ?web sites? features a negative linear relationship, whereas the service ?Usenet? hows a negative exponential relationship. (5) Only 1.54\% of the spam emails showed an interrelation between the topic of the spam email and that of the location where the recipient?s address was placed, so that spammers are assumed to send their emails in a ?context insensitive? manner. The results of the empirical analysis motivate the need for the protection of email addresses through obscuration. We analyze this need by formulating requirements for address obscuring techniques and we reveal to which extent today?s most relevant approaches fulfill these requirements. AU - Schryen, Guido ID - 5658 IS - 5 JF - Computers & Security KW - Address-obfuscating techniques KW - email KW - empirical analysis KW - honeypot KW - security by design KW - security by obscurity KW - spam TI - The Impact that Placing Email Addresses on the Internet has on the Receipt of Spam ? An Empirical Analysis VL - 2 ER - TY - CONF AB - Spam e-mails have become a serious technological and economic problem. So far we have been reasonably able to resist spam e-mails and use the Internet for regular communication by deploying complementary anti-spam approaches. However, if we are to avert the danger of losing the Internet email service as a valuable, free, and worldwide medium of open communication, anti-spam activities should be performed more systematically than is done in current, mainly heuristic, anti-spam approaches. A formal framework within which the modes of spam delivery, anti-spam approaches, and their effectiveness can be investigated, may encourage a shift in methodology and pave the way for new, holistic anti-spam approaches. This paper presents a model of the Internet e-mail infrastructure as a directed graph and a deterministic finite automaton, and draws on automata theory to formally derive the modes of spam delivery possible. Finally the effectiveness of anti-spam approaches in terms of coverage of spamming modes is assessed. AU - Schryen, Guido ID - 5659 T2 - 39th Annual Hawaii International Conference on System Sciences TI - A formal approach towards assessing the effectiveness of anti-spam procedures ER - TY - JOUR AU - Schryen, Guido ID - 5660 IS - 3 JF - IATAC IAnewsletter TI - A honeypot for the exploration of spammers' behaviour VL - 8 ER - TY - CONF AB - Spam has become one of the most annoying and costly phenomenon in the Internet. Valid e-mail addresses belong to the most valuable resources of spammers, but little is known about spammers? behavior when collecting and harvesting addresses and spammers? capabilities and interest in carefully directed, consumer-oriented marketing have not been explored yet. Gaining insight into spammers? ways to obtain and (mis)use e-mail addresses is useful in many ways, e.g. for the assessment of the effectiveness of address obscuring techniques and the usability and necessity of hiding e-mail addresses on the Internet. This paper presents a spam honeypot project in progress addressing these issues by systematically placing e-mail addresses in the Internet and analyzing received e-mails. The honeypot?s conceptual framework, its implementation, and first empirical results are presented. Finally, an outlook on further work and activities is provided. AU - Schryen, Guido ID - 5661 KW - Spam KW - ham KW - e-mail KW - honeypot KW - address obscuring technique KW - address taxonomy T2 - Proceedings of the 6th IEEE Information Assurance Workshop TI - An e-mail honeypot addressing spammers' behavior in collecting and applying addresses ER - TY - CONF AB - Voting via the Internet has become a feasible option for political as well as non-political ballots. However, there are many obstacles which have to be overcome, especially legal restrictions have to be transformed into technical and security solutions. The article starts with a brief presentation of advantages and disadvantages of Internet ballots and presents application fields and pilot schemes. Then, technological security aspects are derived due to democratic basic principles. Especially the applied voting procedures are critical in security terms. Hence, the most relevant cryptographic protocols are presented and their drawbacks and shortcomings are identified. However, this article does not propose a new voting protocol. Beyond fixing cryptographic procedures for ballots, more elements are to be specified, e.g. responsibilities and rights of involved authorities or security precautions regarding hardware and software. For this reason, a structural security framework for electronic voting systems is presented which can be used for their composition and analysis. AU - Schryen, Guido ID - 5765 T2 - 37th Annual Hawaii International Conference on System Sciences TI - Security Aspects of Internet Voting ER - TY - JOUR AB - Spam als unerwünschte Massen-E-Mail hat die Grenze von der Belästigung zur ökonomischen Relevanz längst überschritten. Ihr relativer Anteil am gesamten, weltweiten E-Mail-Aufkommen stieg in den vergangenen Jahren auf mehr als 50% im Jahr 2003. Es entstehen jährlich volkswirtschaftliche Schäden in Milliardenhöhe. Zur Bekämpfung des Spam-Problems werden neben gesetzlichen Regelungen vor allem technische Lösungen eingesetzt, bei denen das Blockieren und Filtern von E-Mails in praktisch eingesetzten Anti-Spam-Systemen dominieren. Dieser Artikel führt in die Spam-Problematik ein und beschreibt, bewertet und klassifiziert die derzeit bedeutendsten Verfahren zur Bekämpfung von Spam. AU - Schryen, Guido ID - 5662 IS - 4 JF - Wirtschaftsinformatik KW - Spam KW - E-Mail KW - Spoofing KW - Blockieren KW - Filtern KW - Lightweight Mail Transfer Agent Authentication Protocol (LMAP) TI - Effektivität von Lösungsansätzen zur Bekämpfung von Spam VL - 46 ER - TY - CONF AB - Spam as unsolicited e-mail to a large number of recipients is known to ecome an increasingly disturbing and costly issue of electronic business and internet traffic. Mainly technical-oriented approaches are applied with a focus on blocking, filtering, and authentication mechanisms based on the domain name system. They come along with different drawbacks and have all low effectiveness in common. The article sketches these approaches, shows its limitations, and proposes an account-based approach where the number of e-mails per day and account is restricted. AU - Schryen, Guido ED - Isaias, Pedro ID - 5663 KW - e-mail KW - spam KW - filtering KW - blocking KW - LMAP KW - SMTP account T2 - Proceedings of the IADIS International Conference WWW/Internet 2004. vol. 2 TI - Fighting Spam: Motivating an Account-based Approach ER - TY - CONF AB - Remote Internet voting systems still suffer from many security problems which rely on the clients, the servers, and the network connections. Denial-ofservice attacks and viruses still belong to the most challenging security issues. Projects and studies like the ?Voting Technology Project? of CALTECH and MIT or SERVE of the US Department of Defense set up to gain experience evidence many of the notional weaknesses of current Internet voting systems. AU - Schryen, Guido ID - 5664 T2 - Workshop of the ESF TED Programme TI - How Security Problems Can Compromise Remote Internet Voting Systems ER - TY - CHAP AU - Schryen, Guido ED - Gehrke, Gernot ID - 5666 T2 - Digitale Teilung - digitale Integration : Perspektiven der Internetnutzung TI - Neulich am Hotspot - Bringt Mobiles Internet die Menschen ins Netz? ER -