Context: Today’s software development industry requires high-speed software delivery from the development team. In order to do this, organizations make transformation from their conventional software development method to agile development method while preserving customer satisfaction. Even though this approach is becoming popular development method, from security point of view, it has some disadvantage. Because, this method has several constraints imposed such as lack of a complete overview of a product, higher development pace and lack of documentation. Although security-engineering (SE) process is necessary in order to build secure software, no SE process is developed specifically for agile model. As a result, SE processes that are commonly used in waterfall model are being used in agile models. However, there is a clash or disparity between the established waterfall SE processes and the ideas and methodologies proposed by the agile manifesto. This means that, while agile models work with short development increments that adapt easily to change, the existing SE processes work in plan-driven development setting and try to reduce defects found in a program before the occurrence of threats through heavy and inflexible process. This study aims at bridging the gap in agile model and security by providing insightful understanding of the SE process that are used in the current agile industry. Objectives: The objectives of this thesis are to identify and evaluate security activities from high-profile waterfall SE-process that are used in the current agile industry. Then, to suggest the most compatible and beneficial security activities to agile model based on the study results. Methods: The study involved two approaches: systematic literature review and survey. The systematic literature review has two main aims. The first aim is to gain a comprehensive understanding of security in an agile process model; the second one is to identify high-profile SE processes that are commonly used in waterfall model. Moreover, it helped to compare the thesis result with other previously done works on the area. A survey is conducted to identify and evaluate waterfall security activities that are used in the current agile industry projects. The evaluation criteria were based on the security activity integration cost and benefit provides to agile projects. Results: The results of the systematic review are organized in a tabular form for clear understanding and easy analysis. High-profile SE processes and their activities are obtained. These results are used as an input for the survey study. From the survey study, security activities that are used in the current agile industry are identified. Furthermore, the identified security activities are evaluated in terms of benefit and cost. As a result the best security activities, that are compatible and beneficial, are investigated to agile process model. Conclusions: To develop secure software in agile model, there is a need of SE-process or practice that can address security issues in every phase of the agile project lifecycle. This can be done either by integrating the most compatible and beneficial security activities from waterfall SE processes with agile process or by creating new SE-process. In this thesis, it has been found that, from the investigated high-profile waterfall SE processes, none of the SE processes was fully compatible and beneficial to agile projects. / (046) 73 6136215