Computer supported communication and infrastructure are integral parts of modern economy. Their security is of incredible importance to a wide variety of practical domains ranging from Internet service providers to the banking industry and e-commerce, from corporate networks to the intelligence community. Of interest to this workshop are novel knowledge discovery methods addressing this field, e.g. adaptive, active or anticipatory approaches integrating new types of contents and protocols. Equally important are innovative applications demonstrating the effectiveness of data mining in solving real-world security problems.