The current growth of the number of Embedded Systems (ES) and their use in sensitive systems attract the attention of attackers. They are exposed to real threats and incur significant risks especially when they are involved in specific military or industrial systems. It is important to study the subject from different angles to understand, predict and learn how to protect our products against these attacks. So, evaluators of Embedded Systems (ES) need to organize structure and classify attacks in order to choose the relevant test sets. To do this, we propose a new classification of attacks on Embedded Systems, based on Classification Tree Method (CTM). As a result, thanks to our proposal, we were able to classify the various attacks en Embedded Systems (ES) to generate test cases automatically and usually select the relevant test cases. This allows to properly evaluate Embedded Systems (ES) especially since this type of system is very critical and requires a systematic evaluation.