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1.	Eidenskog, Maria, 1981-, et al. (författare) Changing the world one engineer at a time – unmaking the traditional engineering education when introducing sustainability subjects 2023 Ingår i: International Journal of Sustainability in Higher Education. - : EMERALD GROUP PUBLISHING LTD. - 1467-6370 .- 1758-6739. ; 24:9, s. 70-84 Tidskriftsartikel (refereegranskat)abstract Purpose: The information technology (IT) sector has been seen as central to society's transformation to a more just and sustainable society, which underlines teachers’ responsibility to foster engineers who can contribute specifically to such ends. This study aims to report an effort to significantly update an existing engineering programme in IT with this ambition and to analyse the effects and challenges associated with the transformation.Design/methodology/approach: This study is based on a combination of action-oriented research based on implementing key changes to the curriculum; empirical investigations including surveys and interviews with students and teachers, and analysis of these; and a science and technology studies-inspired analysis.Findings: Respondents were generally positive towards adding topics relating to sustainability. However, in the unmaking of traditional engineering subjects, changes created a conflict between core versus soft subjects in which the core subjects tended to gain the upper hand. This conflict can be turned into productive discussions by focusing on what kinds of engineers the authors’ educate and how students can be introduced to societal problems as an integrated part of their education.Practical implications: This study can be helpful for educators in the engineering domain to support them in their efforts to transition from a (narrow) focus on traditional disciplines to one where the bettering of society is at the core.Originality/value: This study provides a novel approach to the transformation of engineering education through a theoretical analysis seldom used in studies of higher education on a novel case study.
2.	Asplund, Mikael, 1981-, et al. (författare) A Formal Approach to Autonomous Vehicle Coordination 2012 Ingår i: FM 2012: Formal Methods. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642327582 - 9783642327599 ; , s. 52-67 Bokkapitel (refereegranskat)abstract Increasing demands on safety and energy efficiency will require higher levels of automation in transportation systems. This involves dealing with safety-critical distributed coordination. In this paper we demonstrate how a Satisfiability Modulo Theories (SMT) solver can be used to prove correctness of a vehicular coordination problem. We formalise a recent distributed coordination protocol and validate our approach using an intersection collision avoidance (ICA) case study. The system model captures continuous time and space, and an unbounded number of vehicles and messages. The safety of the case study is automatically verified using the Z3 theorem prover.
3.	Asplund, Mikael, 1981- (författare) Automatically proving the correctness of vehicle coordination 2018 Ingår i: ICT Express. - : Elsevier. - 2405-9595. ; 4:1, s. 51-54 Tidskriftsartikel (refereegranskat)abstract In the next generation of road-based transportation systems, where vehicles exchange information and coordinate their actions, a major challenge will be to ensure that the interaction rules are safe and lead to progress. In this paper we address the problem of automatically verifying the correctness of such distributed vehicular coordination protocols. We propose a novel modeling approach for communicating mobile entities based on the concept of satisfiability modulo theories (SMT). We apply this method to an intersection collision avoidance protocol and show how the method can be used to investigate the settings under which such a protocol achieves safety and progress.
4.	Asplund, Mikael, 1981- (författare) Combining Detection and Verification for Secure Vehicular Cooperation Groups 2020 Ingår i: ACM Transactions on Cyber-Physical Systems. - : ACM Press. - 2378-962X .- 2378-9638. ; 4:1, s. 1-31 Tidskriftsartikel (refereegranskat)abstract Coordinated vehicles for intelligent traffic management are instances of cyber-physical systems with strict correctness requirements. A key building block for these systems is the ability to establish a group membership view that accurately captures the locations of all vehicles in a particular area of interest. In this article, we formally define view correctness in terms of soundness and completeness and establish theoretical bounds for the ability to verify view correctness. Moreover, we present an architecture for an online view detection and verification process that uses the information available locally to a vehicle. This architecture uses an SMT solver to automatically prove view correctness (if possible). We evaluate this architecture using both synthetic and trace-based scenarios and demonstrate that the ability to verify view correctness is on par with the ability to detect view violations.
5.	Asplund, Mikael, 1981- (författare) Disconnected Discoveries: Availability Studies in Partitioned Networks 2011 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract This thesis is concerned with exploring methods for making computing systems more resilient to problems in the network communication, both in the setting of existing infrastructure but also in the case where no infrastructure is available. Specifically, we target a situation called network partitions which means that a computer or device network is split in two or more parts that cannot communicate with each other.The first of the two tracks in the thesis is concerned with upholding system availability during a network partition even when there are integrity constraints on data. This means that the system will optimistically accept requests since it is impossible to coordinate nodes that have no means of communicating during finite intervals; thus requiring a reconciliation process to take place once the network is healed.We provide several different algorithms for reconciling divergent states of the nodes, one of which is able to allow the system to continue accepting operations during the reconciliation phase as opposed to having to stop all invocations. The algorithms are evaluated analytically, proving correctness and the conditions for termination. The performance of the algorithms has been analysed using simulations and as a middleware plugin in an emulated setting.The second track considers more extreme conditions where the network is partitioned by its nature. The nodes move around in an area and opportunistically exchange messages with nodes that they meet. This as a model of the situation in a disaster area where the telecommunication networks are disabled. This scenario poses a number of challenges where protocols need to be both partition-tolerant and energy-efficient to handle node mobility, while still providing good delivery and latency properties.We analyse worst-case latency for message dissemination in such intermittently connected networks. Since the analysis is highly dependent on the mobility of the nodes, we provide a model for characterising connectivity of dynamic networks. This model captures in an abstract way how fast a protocol can spread a message in such a setting. We show how this model can be derived analytically as well as from actual trace files.Finally, we introduce a manycast protocol suited for disaster area networks. This protocol has been evaluated using simulations which shows that it provides very good performance under the circumstances, and it has been implemented as a proof-of-concept on real hardware.
6.	Asplund, Mikael, 1981-, et al. (författare) Emerging Information Infrastructures : Cooperation in Disasters 2009 Ingår i: Critical Information Infrastructure Security. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642035517 - 9783642035524 ; , s. 258-270 Konferensbidrag (refereegranskat)abstract In this paper we describe how to include high level semantic information, such as aesthetics and emotions; into Content Based Image Retrieval. We present a, color-based emotion-related image descriptor that can be used for describing the emotional content of images. The color emotion metric used is derived from psychophysical experiments rind based oil three variables: activity, weight and teat. It was originally designed for single-colors, bill, recent research has shown that the salve emotion estimates call be applied in the retrieval of multi-colored images. Here we describe a new approach, based oil the assumption that perceived color emotions in images are mainly affected by homogenous regions, defined by the emotion metric; and transitions between regions. RGB coordinates are converted to emotion coordinates, mid for each emotion channel, statistical measurements of gradient magnitudes within a. stack of low-pass filtered images are used for finding interest; points corresponding to homogeneous regions and transitions between regions. Emotion characteristics are derived for patches surrounding cacti interest, point, and saved in a, bag-of-emotions; that for instance, can be used for retrieving images based oil emotional content.
7.	Asplund, Mikael, 1981-, et al. (författare) Formalising Reconciliation in Partitionable Networks with Distributed Services 2006 Ingår i: Rigorous Development of Complex Fault-Tolerant Systems. - Heidelberg : Springer Verlag. - 3540482652 ; , s. 37-58 Bokkapitel (refereegranskat)abstract This book brings together 19 papers focusing on the application of rigorous design techniques to the development of fault-tolerant, software-based systems. It is an outcome of the REFT 2005 Workshop on Rigorous Engineering of Fault-Tolerant Systems held in conjunction with the Formal Methods 2005 conference at Newcastle upon Tyne, UK, in July 2005.
8.	Asplund, Mikael, 1981-, et al. (författare) In-store payments using Bitcoin 2018 Ingår i: 9th IFIP International Conference on New Technologies, Mobility and Security (NTMS). - : IEEE. - 9781538636626 - 9781538636633 Konferensbidrag (refereegranskat)abstract The possibility of in-store payments would further increase the potential usefulness of cryptocurrencies. However, this would require much faster transaction verification than current solutions provide (one hour for Bitcoin) since customers are likely not prepared to wait a very long time for their purchase to be accepted by a store. We propose a solution for enabling in-store payments with waiting times in the order of a few seconds, which is still compatible with the current Bitcoin protocol. The idea is based on a payment card in combination with a protocol for ensuring that losing a card does not mean losing the money on it. We analyse the required transaction verification delay and also the potentially added risks that the solution brings compared to current systems.
9.	Asplund, Mikael, 1981-, et al. (författare) Integrering av den sociala dimensionen i datautbildningar 2019 Ingår i: Bidrag från 7:e Utvecklingskonferensen för Sveriges ingenjörsutbildningar. - : Luleå: Luleå tekniska universitet. - 9789177906056 ; , s. 189-190 Konferensbidrag (övrigt vetenskapligt/konstnärligt)
10.	Asplund, Mikael, 1981-, et al. (författare) Measuring Availability in Optimistic Partition-Tolerant Systems with Data Constraints 2007 Ingår i: Dependable Systems and Networks, DSN 2007. - : IEEE Computer Society. - 0769528554 ; , s. 656-665 Konferensbidrag (refereegranskat)abstract Replicated systems that run over partitionable environments, can exhibit increased availability if isolated partitions are allowed to optimistically continue their execution independently. This availability gain is traded against consistency, since several replicas of the same objects could be updated separately. Once partitioning terminates, divergences in the replicated state needs to be reconciled. One way to reconcile the state consists of letting the application manually solve inconsistencies. However, there are several situations where automatic reconciliation of the replicated state is meaningful. We have implemented replication and automatic reconciliation protocols that can be used as building blocks in a partition-tolerant middleware. The novelty of the protocols is the continuous service of the application even during the reconciliation process. A prototype system is experimentally evaluated to illustrate the increased availability despite network partitions.
11.	Asplund, Mikael, 1981- (författare) Model-based Membership Verification in Vehicular Platoons 2015 Ingår i: Proceedings. - : IEEE Computer Society. - 9781467380447 ; , s. 125-132 Konferensbidrag (refereegranskat)abstract Cooperative vehicular systems have the potentialto significantly increase traffic efficiency and safety. However,they also raise the question of to what extent information thatis received from other vehicles can be trusted. In this paperwe present a novel approach for increasing the trustworthinessof cooperative driving through a model-based approach forverifying membership views in vehicular platoons. We define aformal model for platoon membership, cooperative awarenessclaims, and membership verification mechanisms. With the helpof a satisfiability solver, we are able to quantitatively analysethe impact of different system parameters on the verifiability ofreceived information. Our results demonstrate the importance ofcross validating received messages, as well as the surprising diffi-culty in establishing correct membership views despite powerfulverification mechanisms.
12.	Asplund, Mikael, 1981-, et al. (författare) Post-Partition Reconciliation Protocols for Maintaning Consistency 2006 Ingår i: SAC '06 Proceedings of the 2006 ACM symposium on Applied computing. - New York, NY, USA : ACM Press. - 1595931082 ; , s. 710-717 Konferensbidrag (refereegranskat)abstract This paper addresses design exploration for protocols that are employed in systems with availability-consistency trade-offs. Distributed data is modelled as states of objects replicated across a network, and whose updates require satisfaction of integrity constraints over multiple objects. Upon detection of a partition, such a network will continue to provide delivery of services in parallel partitions; but only for updates with non-critical integrity constraints. Once the degraded mode ends, the parallel network partitions are reconciled to arrive at one partition. Using a formal treatment of the reconciliation process, three algorithms are proposed and studied in terms of their influence on service outage duration. The longer the reconciliation time, the lower is system availability; since the interval in which no services are provided is longer. However, the reconciliation time in turn is affected by the time to construct the post-partition system state. The shorter the construction time the higher is the number of updates that took place in the degraded mode but that will not be taken up in the reconciled partition. This will lead to a longer interval for rejecting/redoing these operations and thereby increase reconciliation time.
13.	Asplund, Mikael, 1981- (författare) Poster: Securing Vehicular Platoon Membership 2014 Ingår i: <em>Proceedings of IEEE Vehicular Networking Conference (VNC)</em>. - : IEEE Computer Society. - 9781479976607 ; , s. 119-120 Konferensbidrag (refereegranskat)abstract Vehicular platoons have the potential to bring considerable fuel-savings and increase traffic efficiency. A key component for the next generation platoon systems is a secure membership component which can accommodate membership changes in a dynamic and potentially hostile environment. In this poster paper we analyse the conditions for creating a secure membership protocol which is resilient to attacks and faults in the communication protocols.
14.	Asplund, Mikael, 1981-, et al. (författare) Random walk gossip-based manycast with partition detection 2008 Ingår i: Supplemental Proceedings of the International Conference on Dependable Systems and Networks, DSN, 2008. - : IEEE Computer Society. ; , s. G40-G41 Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
15.	Asplund, Mikael, 1981-, et al. (författare) Rapid selection and dissemination of urgent messages over delay-tolerant networks (DTNs) 2015 Ingår i: Advances in Delay-Tolerant Networks (DTNs). - : Elsevier. - 9780857098405 - 9780857098467 ; , s. 187-203 Bokkapitel (refereegranskat)abstract Today many new applications are emerging that take advantage of wireless communication in handheld and embedded devices. Some of these emerging applications, such as information sharing in vehicular systems, have strong requirements for timely message dissemination, even if the network is not always 100% connected. In this chapter we discuss message differentiation mechanisms that can be used in intermittently connected networks to improve delivery and latency properties when messages have a limited time to live in the network. We present a simulation-based study on a large-scale vehicular scenario comparing different prioritisation mechanisms for a partition-tolerant manycast protocol. We show that negative effects of overloads can be significantly reduced by using information within the message about how far it has spread and how much time is remaining.
16.	Asplund, Mikael, 1981- (författare) Restoring Consistency after Network Partitions 2007 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract The software industry is facing a great challenge. While systems get more complex and distributed across the world, users are becoming more dependent on their availability. As systems increase in size and complexity so does the risk that some part will fail. Unfortunately, it has proven hard to tackle faults in distributed systems without a rigorous approach. Therefore, it is crucial that the scientific community can provide answers to how distributed computer systems can continue functioning despite faults.Our contribution in this thesis is regarding a special class of faults which occurs whennetwork links fail in such a way that parts of the network become isolated, such faults are termed network partitions. We consider the problem of how systems that have integrity constraints on data can continue operating in presence of a network partition. Such a system must act optimistically while the network is split and then perform a some kind of reconciliation to restore consistency afterwards.We have formally described four reconciliation algorithms and proven them correct. The novelty of these algorithms lies in the fact that they can restore consistency after network partitions in a system with integrity constraints and that one of the protocols allows the system to provide service during the reconciliation. We have implemented and evaluated the algorithms using simulation and as part of a partition-tolerant CORBA middleware. The results indicate that it pays oﬀ to act optimistically and that it is worthwhile to provide service during reconciliation.
17.	Asplund, Mikael, 1981-, et al. (författare) Software-related Energy Footprint of a Wireless Broadband Module 2011 Ingår i: The 9th ACM International Symposium on Mobility Management and Wireless Access (MobiWac). - New York, NY, USA : ACM. - 9781450309011 Konferensbidrag (refereegranskat)abstract Energy economy in mobile devices is becoming an increasinglyimportant factor as the devices become more advancedand rich in features. A large part of the energy footprint of amobile device comes from the wireless communication module,and even more so as the amount of trac increases.In this paper we study the energy footprint of a mobilebroadband hardware module, and how it is aected by software,by performing systematic power consumption measurements.We show that there are several cases where thesoftware does not properly take into account the eect thatdata communication has on the power consumption. Thisopens up for potential energy savings by creating better applicationsthat are aware of the energy characteristics of thecommunication layer.
18.	Asplund, Mikael, 1981-, et al. (författare) Specification, Implementation and Verification of Dynamic Group Membership for Vehicle Coordination 2017 Ingår i: Dependable Computing (PRDC), 2017 IEEE 22nd Pacific Rim International Symposium on. - : IEEE. - 9781509056521 - 9781509056538 ; , s. 321-328 Konferensbidrag (refereegranskat)abstract New advanced traffic management solutions with fully or semi-autonomous vehicles that communicate over a wireless interface to coordinate their driving decisions create new challenges in distributed computing. In this paper we address the problem of dynamic group membership in three stages. First, we propose three criteria to specify correctness and performance of the group views created by such algorithms in terms of soundness, completeness and freshness. Second, we develop a group membership protocol tailored for vehicular coordination. Finally, we show through simulation and model-based verification that the protocol does indeed meet the criteria and provide at least 95% perfect group membership views under as adverse conditions as 70% packet loss or very high churn rate.
19.	Asplund, Mikael, 1981-, et al. (författare) Wireless Ad Hoc Dissemination for Search and Rescue 2010 Ingår i: Proceedings of the 7th International ISCRAM Conference. - : ISCRAM. Konferensbidrag (refereegranskat)abstract In search and rescue scenarios local information on victims and other finds needs to be disseminated rapidly toother rescue workers and team leaders. However, post disaster scenarios may imply the collapse of informationinfrastructure including cellular communication and Internet connectivity. Even if we consider wireless ad hoccommunication as a means of information dissemination we should count on frequent loss of connectivity in thenetwork due to unpredictable mobility and sparse network topologies. In this paper we present the realization ofan existing manycast protocol (random walk gossip) on commodity handheld devices running the Androidplatform. This communication mode is used to demonstrate the potential for distributed informationdissemination on victims and finds. The application layer is an adaptation of an existing surveying informationtool (POSIT) which is now fully decentralized and relies on text communication to achieve energy efficiency.
20.	Bergman, Sara, et al. (författare) Permissioned Blockchains and Distributed Databases : A Performance Study 2020 Ingår i: Concurrency and Computation. - : John Wiley & Sons. - 1532-0626 .- 1532-0634. ; 32:12 Tidskriftsartikel (refereegranskat)abstract Blockchains are increasingly studied in the context of new applications. Permissioned blockchains promise to deal with the issue of complete removal of trust, a notion that is currently the hallmark of the developed society. Before the idea is adopted in contexts where resource efficiency and fast operation is a requirement, one could legitimately ask the question: can permissioned blockchains match the performance of traditional large‐scale databases? This paper compares two popular frameworks, Hyperledger Fabric and Apache Cassandra, as representatives of permissioned blockchains and distributed databases, respectively. We compare their latency for varying workloads and network sizes. The results show that, for small systems, blockchains can start to compete with traditional databases, but also that the difference in consistency models and differences in setup can have a large impact on the resulting performance.
21.	Bianzino, Aruna Prem, et al. (författare) Cooperative proxies: Optimally trading energy and quality of service in mobile devices 2014 Ingår i: Computer Networks. - : Elsevier. - 1389-1286 .- 1872-7069. ; 75:Part A, s. 297-312 Tidskriftsartikel (refereegranskat)abstract This work studies the energy and quality of service (QoS) trade-off in the context of mobile devices with two communication interfaces (a high energy and a low energy interface). We propose an optimisation scheme during underload scenarios where proxy groups are dynamically formed exploiting both interfaces. The scheme integrates a reward mechanism that compensates a proxy while carrying other group members’ traffic, and deals with churn (joining and leaving of nodes) in a cell area. For traffic flows that approximate knowledge about current services we show that the scheme can achieve energy savings of 60% for all mobile nodes as whole. We also demonstrate the impact on disruption-sensitive flows as a function of the traffic mix, and that the use of rewards for selection of proxies is a fair mechanism in the long term.
22.	Boeira, Felipe, 1992- (författare) Authentic Communication and Trustworthy Location in Mobile Networks 2023 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Widespread mobile network connectivity has changed society and, consequently, increased our dependency on its proper functioning for transportation, safety, finance, and more. This thesis is concerned with improving the security of mobile networks and focuses on two such instances: vehicular and cellular networks. We aim at mitigating certain security risks even in the presence of strong attackers, which could be manifested in the form of internal malicious agents in cellular network providers or connected vehicles compromised with malicious software, to mention a couple of examples. Within this scope, we target two main challenges: proving that a selected set of security protocols in vehicular and cellular networks guarantee the expected security properties and improving the trustworthiness of location information shared by neighbouring vehicles. Our contributions to security protocols involve employing formal methods to verify security properties in the vehicular communication protocol Ensemble and in the fifth generation of cellular networks (5G). The Ensemble protocol aims to enable multi-brand truck platooning and is currently in a prestandardisation effort in Europe. We report a potential weakness that was resolved in the latest versions and verify that strong security properties are fulfilled. To make verification tractable, we propose a strategy based on the hierarchy of cryptographic keys which may also be employed in protocols that have similar keying structures. In 5G, we identify a weakness that could be exploited to frame people into suspicion of serious crimes when lawful interception operations are conducted. We then design the changes required to guarantee non-frameability in 5G and formally verify the expected security properties. In the context of location trustworthiness, we design and evaluate a proof-of-location scheme tailored for vehicular networks called Vouch+. Vouch+ can operate in centralised or decentralised modes and combines location information shared by neighbouring vehicles (or the infrastructure) with a plausibility model to ensure the validity of the position claimed by other vehicles. Furthermore, we propose and evaluate reaction strategies that mitigate the studied position falsification attacks on vehicular platooning. Through our results, we demonstrate how mobile networks may benefit from employing rigorous methods to obtain higher assurance about their expected security properties. Furthermore, we show how considering increasing adversarial capabilities supports the assessment of these networks’ resilience and the design of new security mechanisms.
23.	Boeira, Felipe, 1992-, et al. (författare) Exploiting Partial Order of Keys to Verify Security of a Vehicular Group Protocol 2022 Ingår i: 2022 IEEE 35TH COMPUTER SECURITY FOUNDATIONS SYMPOSIUM (CSF 2022). - : IEEE COMPUTER SOC. - 9781665484176 - 9781665484183 ; , s. 305-318 Konferensbidrag (refereegranskat)abstract Vehicular networks will enable a range of novel applications to enhance road traffic efficiency, safety, and reduce fuel consumption. As for other cyber-physical systems, security is essential to the deployment of these applications and standardisation efforts are ongoing. In this paper, we perform a systematic security evaluation of a vehicular platooning protocol through a thorough analysis of the protocol and security standards. We tackle the complexity of the resulting model with a proof strategy based on a relation on keys. The key relation forms a partial order, which encapsulates both secrecy and authenticity dependencies. We show that our order-aware approach makes the verification feasible and proves authenticity properties along with secrecy of all keys used throughout the protocol.
24.	Cucurull, Jordi, 1981-, et al. (författare) Anomaly detection and mitigation for disaster area networks 2010 Ingår i: Recent Advances in Intrusion Detection. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642155116 - 3642155111 ; , s. 339-359 Bokkapitel (refereegranskat)abstract One of the most challenging applications of wireless networking are in disaster area networks where lack of infrastructure, limited energy resources, need for common operational picture and thereby reliable dissemination are prevalent.In this paper we address anomaly detection in intermittently connected mobile ad hoc networks in which there is little or no knowledge about the actors on the scene, and opportunistic contacts together with a store-and-forward mechanism are used to overcome temporary partitions. The approach uses a statistical method for detecting anomalies when running a manycast protocol for dissemination of important messages to k receivers. Simulation of the random walk gossip (RWG) protocol combined with detection and mitigation mechanisms is used to illustrate that resilience can be built into a network in a fully distributed and attack-agnostic manner, at a modest cost in terms of drop in delivery ratio and additional transmissions. The approach is evaluated with attacks by adversaries that behave in a similar manner to fair nodes when invoking protocol actions.
25.	Grimsdal, Gunnar, et al. (författare) Can Microkernels Mitigate Microarchitectural Attacks? 2019 Ingår i: Secure IT Systems. - Cham : Springer. - 9783030350543 - 9783030350550 ; , s. 238-253 Bokkapitel (refereegranskat)abstract Microarchitectural attacks such as Meltdown and Spectre have attracted much attention recently. In this paper we study how effective these attacks are on the Genode microkernel framework using three different kernels, Okl4, Nova, and Linux. We try to answer the question whether the strict process separation provided by Genode combined with security-oriented kernels such as Okl4 and Nova can mitigate microarchitectural attacks. We evaluate the attack effectiveness by measuring the throughput of data transfer that violates the security properties of the system. Our results show that the underlying side-channel attack Flush+Reload used in both Meltdown and Spectre, is effective on all investigated platforms. We were also able to achieve high throughput using the Spectre attack, but we were not able to show any effective Meltdown attack on Okl4 or Nova.
26.	Hultman, Tim, et al. (författare) Connectivity-optimal Shortest Paths Using Crowdsourced Data 2016 Ingår i: 2016 IEEE International Conference on Pervasive Computing and Communication Workshops (PerCom Workshops). - : IEEE Computer Society. - 9781509019410 ; , s. 1-6 Konferensbidrag (refereegranskat)abstract With the increasing dependency of ubiquitous connectivity for applications ranging from multimedia entertainment to intelligent transportation systems, having good signal coverage becomes vital. Therefore, route planners and navigation systems should take into account not only the physical distance, but also the characteristics and availability of the cellular network on the potential routes. In this paper we present a route planning tool that finds the connectivity-aware shortest paths based on crowdsourced data from OpenStreetMap and OpenSignal. The tool calculates optimal paths and allows physical distance tobe traded against signal quality. The evaluation shows that a 15% increase of the physical path length can achieve an 8.7dBm improvement of worst-case signal strength.
27.	Lin, Chih-Yuan, 1987- (författare) A timing approach to network-based anomaly detection for SCADA systems 2020 Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract Supervisory Control and Data Acquisition (SCADA) systems control and monitor critical infrastructure in society, such as electricity transmission and distribution systems. Modern SCADA systems are increasingly adopting open architectures, protocols, and standards and being connected to the Internet to enable remote control. A boost in sophisticated attacks against SCADA systems makes SCADA security a pressing issue. An Intrusion Detection System (IDS) is a security countermeasure that monitors a network and tracks unauthenticated activities inside the network. Most commercial IDSs used in general IT systems are signature-based, by which an IDS compares the system behaviors with known attack patterns. Unfortunately, recent attacks against SCADA systems exploit zero-day vulnerabilities in SCADA devices which are undetectable by signature-based IDSs.This thesis aims to enhance SCADA system monitoring by anomaly detection that models normal behaviors and finds deviations from the model. With anomaly detection, zero-day attacks are possible to detect. We focus on modeling the timing attributes of SCADA traffic for two reasons: (1) the timing regularity fits the automation nature of SCADA systems, and (2) the timing information (i.e., arrival time) of a packet is captured and sent by a network driver where an IDS is located. Hence, it’s less prone to intentional manipulation by an attacker, compared to the payload of a packet.This thesis first categorises SCADA traffic into two groups, request-response and spontaneous traffic, and studies data collected in three different protocol formats (Modbus, Siemens S7, and IEC-60870-5-104). The request-response traffic is generated by a polling mechanism. For this type of traffic, we model the inter-arrival times for each command and response pair with a statistical approach. Results presented in this thesis show that request-response traffic exists in several SCADA traffic sets collected from systems with different sizes and settings. The proposed statistical approach for request-response traffic can detect attacks having subtle changes in timing, such as a single packet insertion and TCP prediction for two of the three SCADA protocols studied.The spontaneous traffic is generated by remote terminal units when they see significant changes in measurement values. For this type of traffic, we first use a pattern mining approach to find the timing characteristics of the data. Then, we model the suggested attributes with machine learning approaches and run it on traffic collected in a real power facility. We test our anomaly detection model with two types of attacks. One causes persistent anomalies and another only causes intermittent ones. Our anomaly detector exhibits a 100% detection rate with at most 0.5% false positive rate for the attacks with persistent anomalies. For the attacks with intermittent anomalies, we find our approach effective when (1) the anomalies last for a longer period (over 1 hour), or (2) the original traffic has relatively low volume.
28.	Lin, Chih-Yuan, 1987- (författare) Network-based Anomaly Detection for SCADA Systems : Traffic Generation and Modeling 2022 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Supervisory Control and Data Acquisition (SCADA) systems control and monitor critical infrastructure in society, such as electricity transmission and distribution systems. Modern SCADA systems are increasingly adopting open standards and being connected to the Internet to enable remote control. A boost in sophisticated attacks against SCADA systems makes SCADA security a pressing issue. An Intrusion Detection System (IDS) is a security countermeasure that monitors a network and tracks unauthenticated activities inside the network. Most commercial IDSs used in general IT systems are signature-based, by which an IDS compares the system behaviors with known attack patterns. Unfortunately, recent attacks against SCADA systems exploit zero-day vulnerabilities which are undetectable by signature-based IDSs. This thesis aims to enhance SCADA system monitoring by network-based anomaly detection that models normal behaviors and finds deviations from the model. With network-based anomaly detection, zero-day attacks are possible to detect. There are two main challenges for network-based anomaly detection. The first challenge is the potentially large number of false positives coming from benign traffic that just deviates from the trained model due to the noises. To address this challenge, this thesis proposes several traffic modeling approaches based on statistics and machine learning techniques for the regular communication patterns in SCADA traffic. The second challenge is the lack of open datasets to evaluate the proposed approaches. Consequently, this thesis proposes a traffic generation framework. For traffic modeling, this thesis first categorises SCADA traffic into two groups, request-response and non-requested traffic, and studies data collected in a diverse set of protocol for-mats (Modbus, Siemens S7, S7+, MMS, IEC-60870-5-104). The request-response traffic is generated by a polling mechanism. For this type of traffic, we model the inter-arrival times for each request and response pair with a statistical approach. Results presented in this thesis show that request-response traffic exists in several SCADA traffic sets collected from systems with different sizes and settings. The proposed statistical approach for request-response traffic can detect attacks having subtle changes in timing. The non-requested traffic is generated by remote terminal units at predefined times or when they see significant changes in measurement values. For this type of traffic, we first use a pattern mining approach to find the timing characteristics of the data. Then, we model the suggested attributes with machine learning approaches. We test our anomaly detection model with two types of attacks. One causes persistent anomalies and another only causes intermittent ones. Our anomaly detector exhibits a 100% detection rate with at most 0.5% false positive rate for the attacks with persistent anomalies. For the attacks with intermittent anomalies, we find our approach effective when anomalous patterns last for a longer period (over 30 minutes). For traffic generation, this thesis conducts a comparative analysis between network traces collected from testbeds and a real power utility. The analysis shows that the testbed traffic may be prone to overly regular patterns. This is considered to be the result of lack of plausible human interactions within the testbed. Therefore, this thesis proposes a traffic generation framework built upon a virtual testbed. The framework provides programmable BOTs to mimic human activities such as commands from the operators and attacks.
29.	Lin, Chih-Yuan, 1987-, et al. (författare) Timing-Based Anomaly Detection in SCADA Networks 2018 Ingår i: Critical Information Infrastructures Security. - Cham : Springer. - 9783319998428 - 9783319998435 ; , s. 48-59 Konferensbidrag (refereegranskat)abstract Supervisory Control and Data Acquisition (SCADA) systems that operate our critical infrastructures are subject to increased cyber attacks. Due to the use of request-response communication in polling, SCADA traffic exhibits stable and predictable communication patterns. This paper provides a timing-based anomaly detection system that uses the statistical attributes of the communication patterns. This system is validated with three datasets, one generated from real devices and two from emulated networks, and is shown to have a False Positive Rate (FPR) under 1.4%. The tests are performed in the context of three different attack scenarios, which involve valid messages so they cannot be detected by whitelisting mechanisms. The detection accuracy and timing performance are adequate for all the attack scenarios in request-response communications. With other interaction patterns (i.e. spontaneous communications), we found instead that 2 out of 3 attacks are detected.
30.	Mohammed, Khodari, et al. (författare) Decentralized Firmware Attestation for In-Vehicle Networks 2019 Ingår i: Proc. of 5th ACM Cyber-Physical System Security Workshop (CPSS 2019). - ACM. Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract Today's vehicles are equipped with a large number of Electronic Control Units (ECUs), which control everything from heating to steering and braking. Due to the increasing complexity and inter-dependency of these units, it has become essential for an ECU to be able to ensure the integrity of the firmware running on other ECU's to guarantee its own correct operation. Existing solutions for firmware attestation uses a centralized approach which means a single point of failure. In this article, we propose and investigate a decentralized firmware attestation scheme for the automotive domain. The basic idea of this scheme is that each ECU can attest the state of those ECU's on which it depends. Two flavors of ECU attestation i.e. parallel and serial solution were designed, implemented and evaluated. The two variants were compared in terms of both detection performance (i.e., the ability to identify unauthorized firmware modifications) and timing performance. Our results show that the proposed scheme is feasible to implement and that the parallel solution showed a significant improvement in timing performance over the serial solution.
31.	Saar de Moraes, Rodrigo, 1992- (författare) Exploring Trade-offs in Concept Design of Integrated Modular Avionic Platform Configurations : Topology Generation, Resource Adequacy, and Dependability 2024 Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract Modern aircraft heavily depend on computer systems to carry out various tasks. From managing flight surfaces and engines to processing radar and imagery data and facilitating communication with other aircraft and ground stations, computers are involved in almost every aspect of an aircraft’s operation. These computer systems, known as Integrated Modular Avionics (IMA) systems, have long life cycles that span several decades and undergo regular updates. Despite this, a significant portion of the overall life cycle costs is determined very early in the life cycle, in the concept design phase. While the early concept stage provides the best opportunity to influence the design of the system and its future costs, it is also the stage where information about the system is most limited. During this early stage, selecting a suitable IMA platform configuration must ensure sufficient resources for the intended aircraft functionalities, particularly in computing and networking capabilities. Additionally, the decisions regarding safety and security measures must align with application requirements. However, this is a complex task due to conflicting requirements, necessitating compromises, and the limited information available at this early stage. This thesis explores the analysis and generation of avionic architecture configurations during the concept stage, addressing the problem on two fronts. The first focuses on verifying whether a chosen IMA platform configuration provides sufficient resources to ensure timely communication for a specified set of avionic applications. The second centers on exploring the conceptual design space to find IMA platform configurations aligned with computing, networking, fault-tolerance, and security application needs. To contribute to the problem’s verification aspect, this thesis introduces two high-level abstractions, namely timed automata and a domain-specific model based on Unified Modelling Languages (UML), to model IMA systems at the concept stage. These are designed to capture inter-process message ex-changes within networked IMA platforms. Additionally, we propose a workflow and a supporting tool explicitly designed to translate our proposed model into a network calculus model for further analysis. The approach’s practicality and scalability are showcased through its application to an avionics use case. In exploring conceptual design space, this thesis proposes NetGAP, a domain-specific method in which interconnection patterns in generic networked system topologies are represented as graph grammars. Combined with Monte Carlo Tree Search and genetic algorithms, these grammars are used to navigate the solution space and generate candidate IMA platform configurations tailored to the requirements of an envisaged application. Through application to an avionics use case, NetGAP is shown to be scalable and suitable for different types of requirements. To further expedite the process, NetGAP has evolved into NeuralGAP. The latter employs graph neural networks to assess network topology compatibility with the target application, accelerating the concept exploration and improving its results.
32.	Strömbäck, Filip, et al. (författare) A Student's View of Concurrency : A Study of Common Mistakes in Introductory Courses on Concurrency 2019 Ingår i: Proceedings of the 2019 ACM Conference on International Computing Education Research. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450361859 ; , s. 229-237 Konferensbidrag (refereegranskat)abstract This paper investigates common misconceptions held by students regarding concurrency in order to better understand how concurrency education can be improved in the future. As a part of the exam in two courses on concurrency and operating systems, students were asked to identify and eliminate any concurrency issues in a piece of code as a part of their final exam. Different types of mistakes were identified and the 216 answers were sorted into categories accordingly. The results presented in this paper show that while most students were able to identify the cause of an issue given its symptoms, only approximately half manage to successfully eliminate the concurrency issues. Many of the incorrect solutions fail to associate shared data with a synchronization primitive, e.g. using one lock to protect multiple instances of a data structure, or multiple locks to protect the same instance in different situations. This suggests that students may not only have trouble dealing with concepts related to concurrency, but also more fundamental concepts related to the underlying computational model. Finally, this paper proposes possible explanations for the students' mistakes in terms of improper mental models, and suggests types of problems that highlight the issues with these mental models to improve students' understanding of the subject.
33.	Udd, R., et al. (författare) Exploiting bro for intrusion detection in a SCADA system 2016 Ingår i: CPSS 2016 - Proceedings of the 2nd ACM International Workshop on Cyber-Physical System Security, Co-located with Asia CCS 2016. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450342889 ; , s. 44-51 Konferensbidrag (refereegranskat)abstract Supervisory control and data acquisition (SCADA) systems that run our critical infrastructure are increasingly run with Internet-based protocols and devices for remote monitoring. The embedded nature of the components involved, and the legacy aspects makes adding new security mechanisms in an efficient manner far from trivial. In this paper we study an anomaly detection based approach that enables detecting zero-day malicious threats and benign malconfigurations and mishaps. The approach builds on an existing platform (Bro) that lends itself to modular addition of new protocol parsers and event handling mechanisms. As an example we have shown an application of the technique to the IEC-60870-5-104 protocol and tested the anomaly detector with mixed results. The detection accuracy and false positive rate, as well as real-time response was adequate for 3 of our 4 created attacks. We also discovered some additional work that needs to be done to an existing protocol parser to extend its reach.
34.	Vergara Alonso, Ekhiotz Jon, 1986-, et al. (författare) Fairness and Incentive Considerations in Energy Apportionment Policies 2016 Ingår i: ACM Transactions on Modeling and Performance Evaluation of Computing Systems. - : ACM Digital Library. - 2376-3639 .- 2376-3647. ; 2:1 Tidskriftsartikel (refereegranskat)abstract The energy consumption of a system is determined by the system component usage patterns and interactions between the coexisting entities and resources. Energy accounting plays an essential role to reveal the contribution of each entity to the total consumption and for energy management. Unfortunately, energy accounting inherits the apportionment problem of accounting in general, which does not have a general single best solution. In this paper we leverage cooperative game theory commonly used in cost allocation problems to study the energy apportionment problem, i.e., the problem of prescribing the actual energy consumption of a system to the consuming entities (e.g., applications, processes or users of the system).We identify five relevant fairness properties for energy apportionment and present a detailed categorisation and analysis of eight previously proposed energy apportionment policies from different fields in computer and communication systems. In addition, we propose two novel energy apportionment policies based on cooperative game theory which provide strong fairness notion and a rich incentive structure. Our comparative analysis in terms of the identified five fairness properties as well as information requirement and computational complexity shows that there is a trade-off between fairness and the other evaluation criteria. We provide guidelines to select an energy apportionment policy depending on the purpose of the apportionment and the characteristics of the system.
35.	Vergara Alonso, Ekhiotz Jon, et al. (författare) Sharing the Cost of Lunch : Energy Apportionment Policies 2015 Ingår i: Proceedings of the 11th ACM Symposium on QoS and Security for Wireless and Mobile Networks. - New York, NY, USA : ACM Digital Library. - 9781450337571 ; , s. 91-97 Konferensbidrag (refereegranskat)abstract Energy consumption has become a hot topic in computer and communication technologies pinpointing the need to carefully analyse system efficiency. The energy consumption of a system is determined by the usage patterns of system components and complex interactions between the coexisting entities and resources. Providing transparency of a system’s consumption by breaking down the total consumption is vital to evaluate and provide energy-efficient design and operation.In this paper we survey the apportionment problem in different fields such as computer systems, wireless sensor networks, mobile devices and energy-efficient buildings. The challenge lies in how to attribute a share of the total energy consumption to the responsible entities (e.g., applications, processes or users of the system). Our analysis identifies that energy apportionment is a common problem in different fields and reviews five previously applied energy apportionment policies. Also, the work identifies relevant further research.
36.	Viel, Brieuc, et al. (författare) Why is fingerprint-based indoor localization still so hard? 2014 Ingår i: IEEE International Conference on Pervasive Computing and Communications Workshops (PERCOM Workshops). - : IEEE Computer Society. - 9781479927364 ; , s. 443-448 Konferensbidrag (refereegranskat)abstract Wireless indoor localization systems and especially signal strength fingerprinting techniques have been the subject of significant research efforts in the last decades. However, most of the proposed solutions require a costly site-survey to build the radio map which can be used to match radio signatures with specific locations. We investigate a novel indoor localization system that addresses the data collection problem by progressively and semi-autonomously creating a radio-map with limited interaction cost. Moreover, we investigate how spatiotemporal and hardware properties-based variations can affect the RSSI values collected and significantly influence the resulting localization. We show the impact of these fluctuations on our system and discuss possible mitigations.
37.	Wilson, Johannes, 1996-, et al. (författare) Extending the Authentication Hierarchy with One-Way Agreement 2023 Ingår i: 2023 IEEE 36th Computer Security Foundations Symposium (CSF). - Los Alamitos, CA, USA : IEEE Computer Society. - 9798350321920 - 9798350321937 ; , s. 214-228 Konferensbidrag (refereegranskat)abstract Providing authenticated interactions is a key responsibility of most cryptographic protocols. When designing new protocols with strict security requirements it is therefore essential to formally verify that they fulfil appropriate authentication properties. We identify a gap in the case of protocols with unilateral (one-way) authentication, where existing properties are poorly adapted. In existing work, there is a preference for defining strong authentication properties, which is good in many cases but not universally applicable. In this work we make the case for weaker authentication properties. In particular, we investigate one-way authentication and extend Lowe's authentication hierarchy with two such properties. We formally prove the relationship between the added and existing properties. Moreover, we demonstrate the usefulness of the added properties in a case study on remote attestation protocols. This work complements earlier work with additional generic properties that support formal verification of a wider set of protocol types.

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