As attackers increasingly use more sophisticated techniques to gain a foothold within a company, there is a heightened need for businesses to evaluate and improve their defensive measures. Effective targeted attack simulations requires not only a strong testing capability, but also a good understanding of attacker tradecraft. The targeted attack simulations performed by Yoroi include an in-depth study of the goals considered critical by the client, in order to create attack tools and bespoke malware to test security systems and security policies in use at the limit of their capabilities. The purpose of the simulation is to highlight normally hidden weaknesses to common broad range threats and provide as much information, guidance and support to mitigate risk and the identified attack vectors in order to achieve the best security posture for the entire organisation. A targeted attack simulation performed by Yoroi provides clear guidance on the effectiveness of the policies in place, staff training and adopted defence tools.