关键词: 危急度, 入侵检测系统, 警报, 网络攻击, 模型

Abstract: When lots of alerts are simultaneously presented to the administrator，the decisions are made according to the network attack severity，network attack classification and attack effect.But these concepts do not consider the response opportunity，the sequence of the invasion happening and so on.It only reflects the static information.Based on the status quo，the conception of Alert Urgent Degree（AUD） is proposed.This conception considers the following factors for the first time：（1）the trustworthy degree and the frequency of the alert.（2）the elapsed time from the beginning of alert.（3）the cost of responding to the intrusion.Furthermore，the direct factors which affect the AUD are considered and the indirect factors which relate the intrusion are introduced also.Lastly，based on the illation of mathematic，this paper presents the model of AUD.

Key words: Alert Urgent-Degree（AUD）, Intrusion Detection Systems（IDS）, alert, network attack severity, modeling