Attack trees are widely considered in the fields of security for the analysis of risks (or threats) against electronics, computer control, or physical systems. A major barrier is that attack trees can become largely complex and thus hard to specify. This paper presents ATSyRA, a tooling environment to automatically synthesize attack trees of a system under study. ATSyRA provides advanced editors to specify high-level descriptions of a system, high-level actions to structure the tree, and ways to interactively refine the synthesis. We illustrate how users can specify a military building, abstract and organize attacks, and eventually obtain a readable attack tree.