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February 29, 2012

(Cancelled. To be rescheduled)

Speaker: Yashar Ganjali, Assistant Professor, Department of Computer Science, University of Toronto

Title: Spammer Identification in Telephone Networks

Abstract: Spam over Internet Telephony (SPIT) is a new form of spam delivered using the phone network. With the low cost of Internet telephony, SPIT has become an attractive alternative for spammers to carry out unsolicited marketing and phishing. SPIT is more intrusive than email spam as it demands immediate recipient attention. \r\n\r\nIn this talk, I will present individual and network-wide characteristics of communications in a phone network with the objective of identifying ``SPITters''. Our analysis is based on data collected from one of the largest phone providers in North America. We study the typical communication patterns in terms of several basic metrics including node degree, call duration, call frequency, neighbourhood connectivity, and call density. \r\n\r\nI also present slightly more complex metrics, namely tie strengths, and node ranks. Analyzing the properties of normal behaviour in terms of these metrics, I show that a combination of tie strength and node ranks can be very effective for identifying potential SPITters. We verify the results by comparing the outliers, and by taking a closer look at their basic statistical properties.

Biography: Yashar Ganjali is an assistant professor of computer science at the University of Toronto. He is a member of Computer Systems and Networks Group. He received his BSc in Computer Engineering from Sharif University of Technology, and his MSc in Computer Science from University of Waterloo. He completed his PhD in Electrical Engineering at Stanford University. His PhD dissertation studied the buffer sizing problem in Internet core routers, and showed the possibility of reducing buffer sizes from millions of packets to just a few packets in Internet core routers.\r\n\r\n\r\nDr. Ganjali's research interests include packet switching architectures/algorithms, software defined networks, congestion control, network measurements, and online social networks. He has received several awards for his research including best paper award in Internet Measurement Conference 2008, best paper runner up in IEEE INFOCOM 2003, best demo runner up in! SIGCOMM 2008, first and second prizes in NetFPGA Design Competition 2010, and a Cisco Research Award.

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