www.tjprc.org editor@tjprc.org International Journal of Computer Science Engineering and Information Technology Research (IJCSEITR) ISSN(P): 2249-6831; ISSN(E): 2249-7943 Vol. 4, Issue 2, Apr 2014, 237-244 © TJPRC Pvt. Ltd. DETERMINING AND BLOCKING OF SYBIL USERS ON ONLINE SOCIAL NETWORK MAHENDRA EKNATH PAWAR 1 & B. W. BALKHANDE 2 1 Department of Computer Engineering, Bharati Vidyapeeth College of Engineering, Navi Mumbai, Maharashtra, India 2 Professor, Department of Computer Engineering, Bharati Vidyapeeth College of Engineering, Navi Mumbai, Maharashtra, India ABSTRACT Sybil attacks are one of the well-known and powerful attacks against OSNs. The malicious attacker generates a Sybil group, and pretends to be multiple, distinct users (called Sybil users). Sybil attacks have several harms in OSNs. Dangerous is that multiple Sybil users collude together and form a Sybil group. In this project, we present the first attempt to identify and validate Sybil groups in online social network. We build Sybil group detector based on multiple attributes. We present the first attempt to identify and validate Sybil groups in the real system. First of all, we build the Sybil group detector based on multiple attributes, Including activity, popularity, social degree, friend relationship and IP address. Our Sybil group detection and validation mechanisms have important implications for system design to defend against Sybil attacks in OSNs. KEYWORDS: Detection, Validation, Online Social Networks INTRODUCTION Kinship is a central area of study for social a social network is a social structure made up of a set of social actors (such as individuals or organizations) and a set of the dyadic ties between these actors. The social network perspective provides a set of methods for analyzing the structure of whole social entities as well as a variety of theories explaining the patterns observed in these structures. The study of these structures uses social network analysis to identify local and global patterns, locate influential entities, and examine network dynamics. A social networking site is a platform to build social networks or social relations among people who, for example, share interests, activities, backgrounds, or real-life connections. A social network service consists of a representation of each user (often a profile), his/her social links, and a variety of additional services. Most social network services are web-based and provide means for users to interact over the Internet, such as e-mail and instant messaging. Social networking sites allow users to share ideas, pictures, posts, activities, events, and interest with people in their network. In recent years, online social networks (OSNs) become huge and they are still growing throughout the world. Unfortunately, the relative openness and the tremendous growth of OSNs attract the interest of malicious parties. Sybil attacks are one of the well-known and powerful attacks against OSNs. The malicious attacker generates a Sybil group, and pretends to be multiple, distinct users (called Sybil users). Sybil attacks have several harms in OSNs. First of all, multiple Sybil users are utilized to unfairly increase influence and power of target users. For example, commercial services use many Sybil users and promote clients’ content to the top position in Youtube1. In Twitter, some