This paper presents an automated detection method based on classification of network traffic using predefined set of network metrics. We proposed the set of metrics with focus on behavior of buffer overflow attacks and their sufficient description without the need of deep packet inspection. In this paper we describe two laboratory experiments of automated detection of buffer overflow attacks on vulnerable network services and their description by proposed set of network metrics. We present the principles of several chosen network metrics and their application on experimental attacks according to their nature in comparison to valid communication.