Anagnostopoulos Marios



Marios Anagnostopoulos holds a BSc in Computer Science from Computer Science Department of University of Crete. He received the MSc degree in Information and Communication Systems Security from the University of the Aegean. He also holds a Ph.D. in Information and Communication Systems Engineering from the Dept. of Information and Communication Systems Engineering, University of the Aegean, Greece under the supervision of Associate Prof. Georgios Kambourakis. The title of Ph.D. thesis was "DNS as a multipurpose attack vector" (defence date 2016). His research interests include DNS security, Information and Network security, critical infrastructure security.

Currently, he is Post-Doctoral Research Fellow at the Norwegian University of Science and Technology (Department of Information Security and Communication Technology) and affiliated with the Critical Infrastructure Security and Resilience group of the Center for Cyber and Information Security (CCIS). Before that, he was also Post-Doctoral Research Fellow at the Singapore University of Technology and Design (SUTD).

Research Interests

Network Security, Applications of Cryptography in communications systems, and Network Services and Applications

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M. Anagnostopoulos, S. Lagos, G. Kambourakis, Large-scale empirical evaluation of DNS and SSDP amplification attacks, Journal of Information Security and Applications, Vol. 66, pp. 1-17, 2022, Elsevier,, indexed in SCI-E, IF = 3.872
Reflection-based volumetric distributed denial-of-service (DDoS) attacks take advantage of the available to all (open) services to flood and possibly overpower a victim's server or network with an amplified amount of traffic. This work concentrates on two key protocols in the assailants' quiver regarding DoS attacks, namely domain name system (DNS) and simple service discovery protocol (SSDP). Our contribution spans three axes: (a) We perform countrywide IP address scans (probes) across three countries in two continents to locate devices that run open DNS or SSDP services, and thus can be effectively exploited in the context of amplification attacks, (b) we fingerprint the discovered devices to derive information about their type and operating system, and (c) we estimate the amplification factor of the discovered reflectors through a dozen of diverse, suitably crafted DNS queries and a couple of SSDP ones depending on the case. The conducted scans span fifteen months, therefore comparative conclusions regarding the evolution of the reflectors population over time, as well as indirect ones regarding the security measures in this field, can be deduced. For instance, for DNS, it was calculated that the third quartile of the amplification factor distribution remains more than 30 for customarily exploited queries across all the examined countries, while in the worst case this figure can reach up to 70. The same figures for SSDP range between roughly 41 and 73 for a specific type of query. To our knowledge, this work offers the first full-fledged mapping and assessment of DNS and SSDP amplifiers, and it is therefore anticipated to serve as a basis for further research in this ever-changing and high-stakes network security field.
M. Anagnostopoulos, G. Kambourakis, S. Gritzalis, New facets of Mobile Botnet: Architecture and Evaluation, International Journal of Information Security, Vol. 15, No. 5, pp. 455-473, 2016, Springer,, indexed in SCI-E, IF = 1.915
It is without a doubt that botnets pose a growing threat to the Internet, with DDoS attacks of any kind carried out by botnets to be on the rise. Nowadays, botmasters rely on advanced Command & Control (C&C) infrastructures to achieve their goals and most importantly to remain undetected. This work introduces two novel botnet architectures that consist only of mobile devices and evaluates both their impact in terms of DNS amplification and TCP flooding attacks, and their cost pertaining to the maintenance of the C&C channel. The first one, puts forward the idea of using a continually-changing mobile HTTP proxy in front of the botherder, while the other capitalizes on DNS protocol as a covert channel for coordinating the botnet. That is, for the latter, the messages exchanged among the bots and the herder appear as legitimate DNS transactions. Also, a third architecture is described and assessed, which is basically an optimized variation of the first one. Namely, it utilizes a mixed layout where all the attacking bots are mobile, but the proxy machines are typical PCs not involved in the actual attack. For the DNS amplification attack, which is by nature more powerful, we report an amplification factor that fluctuates between 32.7 and 34.1. Also, regarding the imposed C&C cost, we assert that it is minimal (about 0.25 Mbps) per bot in the worst case happening momentarily when the bot learns about the parameters of the attack.
D. Damopoulos, G. Kambourakis, M. Anagnostopoulos, S. Gritzalis, J. H. Park, User privacy and modern mobile services: Are they on the same path?, Personal and Ubiquitous Computing, Vol. 17, No. 7, pp. 1437-1448, 2013, Springer,, indexed in SCI-E, IF = 1.616
Perhaps, the most important parameter for any mobile application or service is the way it is delivered and experienced by the end-users, who usually, in due course, decide to keep it on their software portfolio or not. Most would agree that security and privacy have both a crucial role to play toward this goal. In this context, the current paper revolves around a key question: Do modern mobile applications respect the privacy of the end-user? The focus is on the iPhone platform security and especially on user’s data privacy. By the implementation of a DNS poisoning malware and two real attack scenarios on the popular Siri and Tethering services, we demonstrate that the privacy of the end-user is at stake.
M. Anagnostopoulos, G. Kambourakis, P. Kopanos, G. Louloudakis, S. Gritzalis, DNS Amplification Attack Revisited, Computers & Security, Vol. 39, pp. 475-485, 2013, Elsevier,, indexed in SCI-E, IF = 1.172
It is without doubt that the Domain Name System (DNS) is one of the most decisive elements of the Internet infrastructure; even a slight disruption to the normal operation of a DNS server could cause serious impairment to network services and thus hinder access to network resources. Hence, it is straightforward that DNS nameservers are constantly under the threat of distributed Denial of Service (DoS) attacks. This paper presents a new, stealthy from the attacker's viewpoint, flavor of DNSSEC-powered amplification attack that takes advantage of the vast number of DNS forwarders out there. Specifically, for augmenting the amplification factor, the attacker utilizes only those forwarders that support DNSSEC-related resource records and advertize a large DNS size packet. The main benefits of the presented attack scenario as compared to that of the typical amplification attack are: (a) The revocation of the need of the aggressor to control a botnet, and (b) the elimination of virtually all traces that may be used toward disclosing the attacker's actions, true identity and geographical location. The conducted experiments taking into consideration three countries, namely Greece, Ireland and Portugal demonstrate that with a proper but simple planning and a reasonable amount of resources, a determined perpetrator is able to create a large torrent of bulky DNS packets towards its target. In the context of the present study this is translated to a maximum amplification factor of 44.
G. Kambourakis, E. Konstantinou, A. Douma, M. Anagnostopoulos, G. Fotiadis, Efficient Certification Path Discovery for MANET, EURASIP Journal on Wireless Communications and Networking, Vol. 2010, pp. 1-16, 2010, Hindawi Publishing Corporation,, indexed in SCI-E, IF = 0.815
A Mobile Ad Hoc Network (MANET) is characterized by the lack of any infrastructure, absence of any kind of centralized administration, frequent mobility of nodes, network partitioning, and wireless connections. These properties make traditional wireline security solutions not straightforwardly applicable in MANETs, and of course, constitute the establishment of a Public Key Infrastructure (PKI) in such networks a cumbersome task. After surveying related work, we propose a novel public key management scheme using the well-known web-of-trust or trust graph model. Our scheme is based on a binary tree formation of the network’s nodes. The binary tree structure is proved very effective for building certificate chains between communicating nodes that are multihops away and the cumbersome problem of certificate chain discovery is avoided.We compare our scheme with related work and show that it presents several advantages, especially when a fair balancing between security and performance is desirable. Simulations of the proposed scheme under different scenarios demonstrate that it is effective in terms of tree formation, join and leave occurrences, and certificate chain establishment.


M. Anagnostopoulos, G. Kambourakis, S. Gritzalis, D. K. Y. Yau, Never say Never: Authoritative TLD nameserver-powered DNS amplification, NOMS 2018 16th IEEE/IFIP Network Operations and Management Symposium, pp. 1-9, 2018, IEEE CPS Conference Publishing Services,
DNS amplification is considered a significant and constant threat to any networking environment. Certainly, the Authoritative Name Servers (ANS) of popular domain zones, and in particular the DNSSEC-enabled ones, do not elude the attention of attackers for entangling them in this type of assaults. The ANS list of Top Level Domains (TLD) are publicly accessible in the form of file, so even a casual attacker is able to acquire the list of TLD zones and their matching ANSs. In this context, the paper at hand examines the potential of ANSs of TLD to be unknowingly engaged by attackers in DNS amplification attacks. In particular, using two distinct versions of the file, we assess the amplification factor that these entities may produce when replying to both individual and multiple queries. As a side-goal, we measure the degree of adoption of Response Rate Limiting (RRL) by ANS. Our most important findings are that (i) an 25% and 37% of unique DNS queries for TLDs produce an amplification factor that respectively exceeds 60 and 50 when the query is sent individually or in batch, and (ii) an almost 43% of unique ANSs do not properly implement RRL or leave it inactive.
M. Anagnostopoulos, G. Kambourakis, P. Drakatos, M. Karavolos, S. Kotsilitis, D. K. Y. Yau, Botnet command and control architectures revisited: Tor Hidden services and Fluxing, The 18th International Conference on Web Information Systems Engineering (WISE 2017), pp. 517-527, 2017, Springer LNCS Vol. 10570,
Botnet armies constitute a major and continuous threat to the Internet. Their number, diversity, and power grows with each passing day, and the last years we are witnessing their rapid expansion to mobile and even IoT devices. The work at hand focuses on botnets which comprise mobile devices (e.g. smartphones), and aims to raise the alarm on a couple of advanced Command and Control (C&C) architectures that capitalize on Tor's hidden services (HS) and DNS protocol. Via the use of such architectures, the goal of the perpetrator is dual; first to further obfuscate their identity and minimize the botnet's forensic signal, and second to augment the resilience of their army. The novelty of the introduced architectures is that it does not rely on static C&C servers, but on rotating ones, which can be reached by other botnet members through their (varied) onion address. Also, we propose a scheme called "Tor fluxing", which opposite to legacy IP or DNS fluxing, does not rely on A type of DNS resource records but on TXT ones. We demonstrate the soundness and effectiveness of the introduced C&C constructions via a proof-of-concept implementation, and suggest possible remedies.
Z. Tsiatsikas, M. Anagnostopoulos, G. Kambourakis, S. Lambrou, D. Geneiatakis, Hidden in plain sight. SDP-based covert channel for Botnet communication, 12th International Conference on Trust, Privacy & Security in Digital Business (TrustBus 2015), 2015, Springer,
Covert channels pose a significant threat for networking systems. In this paper, we examine the exploitation of Session Description Protocol (SDP) information residing in Session Initiation Protocol (SIP)requests with the aim to hide data in plain sight.While a significant mass of works in the literature cope with covert communication channels, only a very limited number of them rely on SIP to realize its goals. Also, none of them concentrates on SDP data contained in SIP messages to implement and evaluate such a hidden communication channel. Motivated by this fact, the work at hand proposes and demonstrates the feasibility of a simple but very effective in terms of stealthiness and simplicity SIP-based covert channel for botnet Command and Control (C&C). As a side contribution, we assess the soundness and the impact of such a deployment at the victim's side via the use of two different types of flooding attacks.
D. Damopoulos, G. Kambourakis, M. Anagnostopoulos, S. Gritzalis, J. H. Park, User-privacy and modern smartphones: A Siri(ous) dilemma, FTRA AIM 2012 International Conference on Advanced IT, Engineering and Management, 2012, FTRA,
The focus of this paper is on iPhone platform security and especially on user’s data privacy. We are designing and implementing a new malware that takes over the iOS mDNS protocol and exposes user's privacy information by capitalizing on the new Siri facility. The attack architecture also includes a proxy server which acts as man-in-themiddle between the device and the Apple's original Siri server.