Gokce Gorbil

Imperial College London, Londinium, England, United Kingdom

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Publications (19)0.9 Total impact

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    Full-text · Article · Jan 2016
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    ABSTRACT: The 30th anniversary of the International Symposium on Computer and Information Sciences (ISCIS) series, which have regularly over this long period of time brought together Computer Scientists from around the world and from Turkey, was held at Imperial College London, UK during 21–24 September 2015. This year the conference attracted 82 submissions from 21 countries—with contributions coming mostly from Europe, America and the Far East—out of which 39 carefully refereed proposals were selected, along with two Invited Papers, for inclusion in the proceedings. Several other Invited Papers were presented orally. In addition to the papers that are contained in these proceedings, the symposium was preceded by a conference comprising some 50 keynote and invited presenta- tions in honour of Prof. Erol Gelenbe, who started ISCIS back in 1986, and kept it going constantly with the help of several colleagues from Europe and Turkey. This volume provides a compact yet broad view of recent developments in the Computer and Information sciences, and covers exciting research areas in the field including Green and Cloud computing, Performance Modelling, Cybersecurity, Big Data, and Smart Algorithm design for computer, biological and chemical systems. This symposium also highlights recent results from the EU FP7 NEMESYS Project. We are very grateful to the authors of all of the submitted papers, and to the authors of accepted papers, for their contributions, and to the technical programme committee members who each evaluated several papers, without whom this exciting programme would not have been possible.
    Full-text · Book · Sep 2015
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    Mihajlo Pavloski · Gokce Gorbil · Erol Gelenbe
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    ABSTRACT: The increase of the number of smart devices using mobile networks' services is followed by the increase of the number of security threats for mobile devices, generating new challenges for mobile network operators. Signalling attacks and storms represent an emerging type of distributed denial of service (DDoS) attacks and happen because of special malware installed on smart devices. These attacks are performed in the control plane of the network, rather than the data plane, and their goal is to overload the Signalling servers which leads to service degradation and even network failures. This paper proposes a detection and mitigation mechanism of such attacks which is based on counting repetitive bandwidth allocations by mobile terminals and blocking the misbehaving ones. The mechanism is implemented in our simulation environment for security in mobile networks SECSIM. The detector is evaluated calculating the probabilities of false positive and false negative detection and is characterised by very low negative impact on un-attacked terminals. Simulation results using joint work of both detector and mitigator, are shown for: the number of allowed attacking bandwidth allocations, end-to-end delay for normal users, wasted bandwidth and load on the Signalling server. Results suggest that for some particular settings of the mechanism, the impact of the attack is successfully lowered, keeping the network in stable condition and protecting the normal users from service degradations.
    Full-text · Conference Paper · Jul 2015
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    ABSTRACT: Mobile networks are vulnerable to signalling attacks and storms that are caused by traffic patterns that overload the control plane, and differ from distributed denial of service (DDoS) attacks in the Internet since they directly affect the control plane, and also reserve wireless bandwidth and network resources without actually using them. Such storms can result from malware and mobile botnets, as well as from poorly designed applications, and can cause service outages in 3G and 4G networks which have been experienced by mobile operators. Since the radio resource control (RRC) protocol in 3G and 4G networks is particularly susceptible to such storms, we analyze their effect with a mathematical model that helps to predict the congestion that is caused by a storm. A detailed simulation model of a mobile network is used to better understand the temporal dynamics of user behavior and signalling in the network and to show how RRC-based signalling attacks and storms cause significant problems in both the control and user planes of the network. Our analysis also serves to identify how storms can be detected, and to propose how system parameters can be chosen to mitigate their effect.
    Full-text · Article · Jan 2015 · IEEE Transactions on Emerging Topics in Computing
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    ABSTRACT: Mobile networks are vulnerable to signalling attacks and storms that are caused by traffic patterns that overload the control plane, and differ from distributed denial of service (DDoS) attacks in the Internet since they directly attack the control plane, and also reserve wireless bandwidth without actually using it. Such attacks can result from malware and mobile botnets, as well as from poorly designed applications, and can cause service outages in 3G and 4G networks which have been experienced by mobile operators. Since the radio resource control (RRC) protocol in 3G and 4G networks is particularly susceptible to such attacks, we analyze their effect with a mathematical model that helps to predict the congestion that is caused by an attack. A detailed simulation model of a mobile network is used to better understand the temporal dynamics of user behavior and signalling in the network and to show how RRC based signalling attacks and storms cause significant problems in the control plane and the user plane of the network. Our analysis also serves to identify how storms can be detected, and to propose how system parameters can be chosen to mitigate their effect.
    Full-text · Article · Nov 2014
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    ABSTRACT: The growing popularity of smart mobile devices such as smartphones and tablets has made them an attractive target for cyber-criminals, resulting in a rapidly growing and evolving mobile threat as attackers experiment with new business models by targeting mobile users. With the emergence of the first large-scale mobile botnets, the core network has also become vulnerable to distributed denial-of-service attacks such as the signaling attack. Furthermore, complementary access methods such as Wi-Fi and femtocells introduce additional vulnerabilities for the mobile users as well as the core network. In this paper, we present the NEMESYS approach to smart mobile network security. The goal of the NEMESYS project is to develop novel security technologies for seamless service provisioning in the smart mobile ecosystem, and to improve mobile network security through a better understanding of the threat landscape. To this purpose, NEMESYS will collect and analyze information about the nature of cyber-attacks targeting smart mobile devices and the core network so that appropriate counter-measures can be taken. We are developing a data collection infrastructure that incorporates virtualized mobile honeypots and honeyclients in order to gather, detect and provide early warning of mobile attacks and understand the modus operandi of cyber-criminals that target mobile devices. By correlating the extracted information with known attack patterns from wireline networks, we plan to reveal and identify the possible shift in the way that cyber-criminals launch attacks against smart mobile devices.
    Full-text · Article · Jul 2013
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    ABSTRACT: As a consequence of the growing popularity of smart mobile devices, mobile malware is clearly on the rise, with attackers targeting valuable user information and exploiting vulnerabilities of the mobile ecosystems. With the emergence of large-scale mobile botnets, smartphones can also be used to launch attacks on mobile networks. The NEMESYS project will develop novel security technologies for seamless service provisioning in the smart mobile ecosystem, and improve mobile network security through better understanding of the threat landscape. NEMESYS will gather and analyze information about the nature of cyber-attacks targeting mobile users and the mobile network so that appropriate counter-measures can be taken. We will develop a data collection infrastructure that incorporates virtualized mobile honeypots and a honeyclient, to gather, detect and provide early warning of mobile attacks and better understand the modus operandi of cyber-criminals that target mobile devices. By correlating the extracted information with the known patterns of attacks from wireline networks, we will reveal and identify trends in the way that cyber-criminals launch attacks against mobile devices.
    Full-text · Article · May 2013 · Lecture Notes in Electrical Engineering
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    G. Gorbil · E. Gelenbe
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    ABSTRACT: In urban emergencies and disasters, emergency support systems enabled by ubiquitous computing and mobile communications can prove very beneficial by providing alerts, guidance and other crucial information to civilians and emergency responders. However, the communication infrastructure that such systems depend upon is usually adversely affected in emergencies due to failures or congestion. Thus we consider the problem of providing emergency support when existing communication infrastructure is unavailable. We propose the use of opportunistic communications (Oppcomms) among mobile devices for the dissemination of emergency information. With Oppcomms, devices exchange messages at a close range of a few to tens of meters with limited or no infrastructure and messages are carried over multiple hops in a “store-carry-forward” manner by exploiting human mobility. We present an emergency support system (ESS) based on Oppcomms to provide evacuation guidance to civilians in large-scale urban emergencies in the absence of other means of communication. We evaluate the performance of ESS with simulation experiments of large-scale evacuation of a district of London, UK. Our evaluations show the improvement Oppcomms can offer.
    Full-text · Conference Paper · Jan 2013
  • G. Gorbil · E. Gelenbe
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    ABSTRACT: We describe an emergency evacuation support system (ESS) that employs short-range wireless communications among mobile devices carried by civilians. Emergency information is disseminated via opportunistic contacts between communication nodes (CNs), and each CN provides adaptive step-by-step navigation directions for its user during evacuation. Using mobile devices and opportunistic communications (oppcomms) allow ESS to operate when other means of communication are destroyed or overloaded. In this paper, we evaluate the resilience of oppcomms as used to enable evacuation support in ESS; we specifically consider the effect of CN failures on evacuation and communication performance. Our simulation experiments of evacuation of a three-floor office building show that ESS is highly resilient to node failures, and failure ratios up to 20 % are well-tolerated.
    No preview · Article · Jan 2013
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    ABSTRACT: We present two spatially distributed computing systems that operate in a building and provide intelligent navigation services to people for evacuation purposes. These systems adapt to changing conditions by monitoring the building and using local communication and computation for determining the best evacuation paths. The first system, called distributed evacuation system (DES), comprises a network of decision nodes (DNs) positioned at specific locations inside the building. DNs provide people with directions regarding the best available exit. The second system, called opportunistic emergency support system (OESS), consists of mobile communication nodes (CNs) carried by people. CNs form an opportunistic network in order to exchange information regarding the hazard and to direct the evacuees towards the safest exit. Both DES and OESS employ sensor nodes deployed at fixed locations for monitoring the hazard. We evaluate the spatial systems using simulation experiments with a purpose-built emergency simulator called DBES. We show how parameters such as the frequency of information exchange and communication range affect the system performance and evacuation outcome.
    Full-text · Article · Nov 2012 · The Computer Journal
  • Gokce Gorbil · Erol Gelenbe
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    ABSTRACT: We describe an autonomous emergency support system (ESS) based on opportunistic communications (oppcomms) to support navigation and evacuation of civilians in built environments. In our proposed system, civilians are equipped with low-cost human wearable devices that employ oppcomms to exchange packets at close range of a few meters with limited or no infrastructure. This paper investigates the resilience and performance of oppcomms in the presence of network attacks. We assume that a portion of nodes in the network have been compromised and misbehave, which adversely affects communications and evacuation. We evaluate the effect of three types of node misbehaviour and propose a defense mechanism against the most serious among these. The defense mechanism combines identity-based cryptography with collaborative malicious packet detection and blacklisting of detected attackers. Results from simulation experiments conducted on a specialized emergency simulator show the impact of misbehaviour on evacuation and communication performance and the improvement offered by the defense mechanism.
    No preview · Conference Paper · Oct 2012
  • Erol Gelenbe · Gokce Gorbil
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    ABSTRACT: Emergencies of different types, ranging from accidents to natural disasters, are unfortunately becoming increasingly common due to the greater concentration of human populations and the existence of highly interconnected physical infrastructures that human beings increasingly rely on. Thus Emergency Management Systems are gaining in importance and they are a major and useful example of Cyber-Physical Systems where ICT, sensing and decision making come together to improve the outcomes for human beings and for nature itself. Our presentation focuses on the impact of wireless sensing, distributed decision making, and opportunistic wireless communications as tools for optimising human evacuation and improving the health outcomes for human populations during small or large scale emergencies.
    No preview · Conference Paper · Aug 2012
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    ABSTRACT: An emergency situation taking place inside a confined space, such as a building, is a challenging task due to the presence of dynamic conditions. Pervasive systems can prove beneficial for the evacuation procedure, as they can provide directions to the evacuees regarding the best available exit. In this paper we describe two pervasive systems geared towards emergency support, which are deployed inside a building. Both systems use simple communications in order to collect and disseminate information regarding the best evacuation paths. We use a multi-agent simulation platform to demonstrate how the use of the systems improves the outcome of the evacuation procedure.
    Full-text · Article · Mar 2012
  • E. Gelenbe · G. Gorbil · Fang-Jing Wu
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    ABSTRACT: Emergency management systems (EMS) are important and complex examples of Cyber-Physical-Human systems that are deployed so as to optimise the outcome of an emergency from a human perspective. They use sensor networks, networked decision nodes and communications with evacuees and first responders to optimise the overall Quality of Service to benefit primarily human beings in terms of survival, health and safety, and the the protection of nature, property and valuable infrastructures. The use of technology for emergency management also has side effects in terms of failures and malicious attacks of the ICT system, so that the outcome will be affected by how well the ICT system operates under stress. Thus this paper surveys research on wireless sensor- assisted EMS, including networking, distributed control, and knowledge discovery. An evaluation of increased effectiveness and liabilities that wireless communications introduce is conducted when adversaries exacerbate the emergency by malicious attacks through the wireless system.
    No preview · Conference Paper · Jan 2012
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    ABSTRACT: The evacuation of a building during an emergency situation, such as a fire, is a complex and challenging task. As the conditions inside the building change due to the spreading of the hazard, it becomes difficult for an evacuee to find the best evacuation path. Information systems can prove beneficial for the evacuees, as they provide them with directions regarding the best path to follow at any given time. In this paper we present two spatially distributed computing systems that operate inside a building. They adapt to the dynamic conditions during an evacuation while relying on local communication and computation for determining the best evacuation paths. The first system is composed of a network of decision nodes (DNs) positioned at specific locations inside the building. Their goal is to provide the evacuees with directions regarding the best available exit. The second system is composed of mobile communication nodes (CNs) carried by the evacuees. They form an opportunistic network in order to exchange information regarding the hazard and to direct the evacuees towards the safest exit. Sensor nodes that monitor the hazard intensity in the building are used by both systems. We use a multi-agent simulation platform that we developed to evaluate the performance of our proposed systems in evacuation scenarios inside multi-storey buildings. We show how parameters such as the frequency of information exchange between the nodes and communication ranges affect the performance of the systems.
    Full-text · Article · Oct 2011
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    A. Filippoupolitis · G. Gorbil · E. Gelenbe
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    ABSTRACT: The evacuation of urban areas during an emergency is complex and challenging due to the dynamic conditions and ambiguity of information available to people in the affected area. Autonomous navigation systems can improve the outcome of such evacuations by providing up-to-date guidance and directions to people during the emergency. In this paper we present two distributed navigation systems deployed inside a confined space, such as a building, that use simple but effective communications to gather and disseminate information for the computation of evacuation paths. The first system is composed of a network of static decision nodes (DNs) positioned in the building, where DNs distributedly compute the best paths using local communication and computation, and each DN provides directions to people in its vicinity. The second system is composed of mobile communication nodes (CNs) carried by the people in the area. CNs form an opportunistic network in order to exchange information regarding the hazard and each CNs directs its user towards the safest/closest exit. Sensor nodes pre-deployed in the building monitor the environment and provide their measurements to both systems. We investigate the effect of failures of DNs on the evacuation outcome and study how the two systems can be used in conjunction to overcome such problems. A multi-agent simulation platform is used for the performance evaluation of our proposed systems in evacuation scenarios inside a three-floor building.
    Full-text · Conference Paper · Jan 2011
  • R. Lent · O.H. Abdelrahman · G. Gorbil · E. Gelenbe
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    ABSTRACT: This paper presents an emergency communication system that is able to quickly deliver emergency messages over an unreliable and best-effort network such as the Internet. The proposed architecture employs application-layer multicast to rapidly deliver emergency traffic without the support of a dedicated network infrastructure. We introduce a distributed overlay tree construction and maintenance mechanism that produces consistent, loop-free and self-adaptive trees that dynamically change over time to effectively deal with varying network conditions and offer low message delays to end nodes. We evaluate the performance of the proposed approach through an experimental study conducted on a real-life networking testbed.
    No preview · Conference Paper · May 2010
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    ABSTRACT: This paper presents a command and control (C2) agents approach to supporting tactical decision making by operational commanders. The work addresses two C2 issues: the use of networked information sharing and high-level information fusion to allow for the visualisation of highly anisotropic threat spaces, and associated route planning for a variety of effects based tasks taking into account a commanderpsilas immediate task needs, personal experience, and command preferences. We adopt wave propagation techniques used in seismology and present illustrations from a software suite we have developed that reflects commander preferences in effects routing, facilitates cooperative command planning, and analysis of opponent options.
    Full-text · Conference Paper · Jan 2008
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    Gokce Gorbil · Erol Gelenbe

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