This paper presents a benchmark for the detection and isolation of cyber attacks, which is a non-linear controlled interconnected system based on a two tank system. In this benchmark, a malicious attacker wants to remain hidden while stealing water by altering the signals of the sensors of the levels of the tanks. It is assumed that the attacker can steal water from the tanks using extraction pumps with pre-established flow rates and, depending on the theft and the type of sensor alteration, different attack scenarios are proposed.