This book is designed to illustrate an approach how to analyse the security aspects in software development using a known technique called attack tree. It guides software developers and security analysts leverage their previous knowledge as context information to prevent the software products at its design phase from malicious attacks. It also provides an understanding for students from IT and related fields to have a glimpse about security in software development. The readers will find the proposed approach interesting and understandable as the approach is shown step by step with a sample case study.