Wtat is KsecDD in NT audit log ?

[Sun Young Geun\(선영근\)]

Hi, Everyone.   My NT server's audit log catch unpreviled log-on trial.   The log says that illegal access used KsecDD process.   What is KsecDD process? And I find ksecdd.sys in c:\winnt\system32 directory.   And how can I defend the illegal log-on trial from outside.   Is it related port 139 ?   Have a nice day !!