Vasileios Vlachos

Power laws in software

A single statistical framework, comprising power law distributions and scale-free networks, seems to fit a wide variety of phenomena. There is evidence that power laws appear in software at the class and function level. We show that distributions with long, fat tails in software are much more pervasive than previously established, appearing at various levels of abstraction, in diverse systems and languages. The implications of this phenomenon cover various aspects of software engineering research and practice.

Security applications of peer-to-peer networks

Open networks are often insecure and provide an opportunity for viruses and DDOS activities to spread. To make such networks more resilient against these kind of threats, we propose the use of a peer-to-peer architecture whereby each peer is responsible for: (a) detecting whether a virus or worm is uncontrollably propagating through the network resulting in an epidemic; (b) automatically dispatching warnings and information to other peers of a security-focused group; and (c) taking specific precautions for protecting their host by automatically hardening their security measures during the epidemic. This can lead to auto-adaptive secure operating systems that automatically change the trust level of the services they provide. We demonstrate our approach through a prototype application based on the JXTA peer-to-peer infrastructure.

The landscape of cybercrime in Greece

Purpose – Cybercrime is a serious threat for most modern societies as it hinders the necessary adoption of information and communication technologies (ICT). This paper seeks to analyze a large number of real cases related to the cybercrime in Greece.Design/methodology/approach – All cases were voluntarily submitted from Greek users, who asked for assistance to a special task force, composed of public sector employees and servants. By analyzing more than 1,000 similar cases, the paper derives a taxonomy of security‐related incidents that the Greek users encountered during the past years. Greece only recently embraced broadband technologies and, therefore, this paper is able to observe the corresponding increase of cybercriminal activities.Findings – An analysis of the reports received by the task force indicate a clear shift in the type of reported content. A large number of recent reports from Greek users concern financial fraud schemes and phenomena of cyberbullying and cyber‐extortions, activities relat...

A PRoactive malware identification system based on the computer hygiene principles

Purpose – To present a new technique that contains the spread of rapid malcode, which is based on peer‐to‐peer (P2P) communication and the principles of computer hygiene.Design/methodology/approach – Two proof‐of‐concept prototypes demonstrate the feasibility of the introduced technique. The effectiveness of the proposed model is supported by experimental findings through simulation tests. Additional software tools have been developed to ensure the correctness of the simulation.Findings – Provides supportive information regarding the efficiency of computer hygiene practices. Moreover, theoretical and empirical results show that P2P networks could play an important role in the containment of worm epidemics.Research limitations/implications – A stable system deployed in large‐scale is yet to be implement in order to produce decisive results regarding the benefits of the proposed algorithm.Practical implications – This paper argues that P2P networks can have significant impact on the containment of the rapid...

The MoR-Trust Distributed Trust Management System: Design and Simulation Results

MoR-Trust is a purely decentralized peer-to-peer trust management system, targeted towards networks and applications supporting transactions or collaborations of a quantitative nature. MoR-Trust is based on the notion of expressing trust in terms of monetary units, thus directly coupling the trust estimates circulated in the network with the values of the transactions taking place and their outcomes. We have validated our design decisions and algorithms through simulation. The results indicate that our system converges towards a small error in the trust estimates distributed throughout the network.

NGCE – network graphs for computer epidemiologists

Graphs are useful data structures capable of efficiently representing a variety of technological and social networks. They are therefore utilized in simulation-based studies of new algorithms and protocols. Inspired by the popular tgff (Task Graphs For Free) toolkit, which creates task graphs for embedded systems, we present the ngce, an easy to use graph generator that produces structures for the study of the propagation of viral agents in complex computer networks. Designated track: Computer Security

Spam goes mobile: Filtering unsolicited SMS traffic

The wide proliferation of mobile devices has attracted the attention of cyber-criminals, who exploit their functionality for malevolent purposes. One of the most popular approaches is the exploitation of sms for generating unsolicited electronic messages, also known as spam. The paper describes the peculiarities of the mobile unsolicited message traffic and proposes an sms spam detection algorithm for mobile devices. The developed prototype can be quite an effective method for fighting SMS spam.

A crowdsourcing approach to protect against novel malware threats

Worm attacks for more than two decades have been affecting the Internet causing instability and economic loses. In a huge pool of possible victims such as the Internet there can exist many targets running the same software with the same vulnerabilities. To prevent such targets from getting infected one can use the crowd experience to identify a possible attack and restrict the use of possible vulnerable software for a certain period. Crowdsourcing intelligence or collaborative intelligence is the power of many when each one in a group of participants shares certain information. It is characterized by enhancing information accuracy which further improves decision making on the group. This paper presents and analyzes NetBuckler, a collaborative client application which employs collaborative intelligence to defend against Internet worms. It also briefly presents JXTA and its potential.

Implementation of an improved reconfigurable SOVA/log-MAP turbo decoder in LTE

SOVA and log-MAP turbo decoding algorithms share common operations. Our analysis shows that the improved reconfigurable SOVA/log-MAP turbo decoder can be implemented in LTE systems for AWGN channel. We examine two data rates, and for each one we consider the nine possible QCIs using five frames. Considering BER and latency limitations for each QCI, SOVA is proposed for most of the cases for low data rates, whereas log-MAP is proposed for higher data rates.

Measuring the Internet's threat level: A global-local approach

The Internet is a highly distributed and complex system consisting of billion devices and has become the field of various kinds of conflicts during the last two decades. As a matter of fact, various actors utilise the Internet for illicit purposes, such as for performing Distributed Denial of Service Attacks (DDoS) and for spreading various types of aggressive malware. Despite the fact that numerous services provide information regarding the threat level of the Internet, they are mostly based on information acquired by their sensors or on offline statistical sampling of various security applications (antivirus software, intrusion detection systems etc.). This paper presents PROTOS (PROactive Threat Observatory System), an early warning system which is capable of estimating the threat level across the Internet, using both a global and a local approach. The proposed system is therefore able to determine whether a specific host is under an imminent threat, as well as to provide an estimation of the malicious activity across the Internet.