2WEN Wei-ping 1,2,3, QING Si-han 1,2,31. Institute of Software, the Chinese Academy of Sciences, Beijing 100080, China,2.Engineering Research Center for Information Security Technology, the Chinese Academy of Sciences, Beijing 100080, China,3.Graduate School of the Chinese Academy of Sciences, Beijing 100080, China.Mechanism and Defense on Malicious Code[J].Wuhan University Journal of Natural Sciences,2005,10(1):83-88.