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Abstract: In recent years, various computers have been compromised through several paths. In particular, the attack patterns and paths are becoming more various than in the past. Furthermore, systems damaged by hackers are used as zombie systems to attack other web servers or personal computers, so there is a high probability to spread secondary damage such as DDoS. Also, previously, hacking and malicious code were carried out for self-display or simple curiosity, but recently they are related to monetary extortion. In order to respond to incidents correctly, it is important to measure the damage to a system rapidly and determine the attack paths. This paper will discuss an on-site investigation methodology for incident response and also describe the limitations of this methodology. [Copyright &y& Elsevier]

Abstract: Parallel key-insulated encryption (PKIE) usually allows two independent helper keys to be alternately used in temporary secret key update operations. At least half of temporary secret keys would be exposed and at least half of ciphertexts could be decrypted if one of the helper keys is exposed. In this paper, we propose a new PKIE scheme with helper keys, where . If one of the helper keys is exposed, only temporary secret keys would be exposed and ciphertexts could be decrypted, so the new PKIE scheme can greatly decrease loss due to key-exposure. The scheme is provably secure without random oracles based on a bilinear group of composite order. Most important, the scheme is practical and much more efficient than the extended ones from the previous PKIE schemes. [Copyright &y& Elsevier]

Abstract: As online games become popular and the boundary between virtual and real economies blurs, cheating in games has proliferated in volume and method. In this paper, we propose a framework for user behavior analysis for bot detection in online games. Specifically, we focus on party play which reflects the social activities among gamers: in a Massively Multi-user Online Role Playing Game (MMORPG), party play is a major activity that game bots exploit to keep their characters safe and facilitate the acquisition of cyber assets in a fashion very different from that of normal humans. Through a comprehensive statistical analysis of user behaviors in game activity logs, we establish threshold levels for the activities that allow us to identify game bots. Based on this, we also build a knowledge base of detection rules, which are generic. We apply our rule reasoner to AION, a popular online game serviced by NCsoft, Inc., a leading online game company based in Korea. [Copyright &y& Elsevier]