Question

这是我第一次尝试挂钩windows API。我的目标是监视进程要创建/打开/读/写的所有文件。为了成为最冗长的可能，我决定挂钩ntdll.dll API，如NtCreateFile（）和NtOpenFile（）。所以，为了实现这个目标，我继续使用EasyHook，它看似简单而强大。我一直遵循FileMon示例，改变我真正想要的东西：Hooked功能。当我尝试读取有关要打开的文件的信息时，我尝试从OBJECT_ATTRIBUTES结构中读取信息，例如 ObjectName。那些是整数指针，所以我希望使用函数Marshal.PtrToStringAuto（attributes.objectName）来获取字符串值。但是，结果是我只能有坏字符串，没有任何意义。此外，文件访问似乎无法正常工作。我猜这有点不对劲代码，可能在DllImport签名中。建议我必须用IntPtr替换SafeHandle，因为EasyHook抱怨他们正在编组。有人能帮助我吗？

这是我注入的DLL的具体代码：

这是Run方法代码

public void Run(RemoteHooking.IContext InContext, String inChannelName) 
        {
            // First of all, install all the hooks
            try
            {
                // NtCreateFile
                fileCreationHook = LocalHook.Create(
                    LocalHook.GetProcAddress("ntdll.dll", "NtCreateFile"),
                    new CreateFileDelegate(CreateFile_Hooked),
                    this
                    );

                fileCreationHook = LocalHook.Create(
                    LocalHook.GetProcAddress("ntdll.dll", "NtOpenFile"),
                    new OpenFileDelegate(OpenFile_Hooked),
                    this
                    );

                fileCreationHook.ThreadACL.SetExclusiveACL(new Int32[] { 0 });
                remoteIf.Log("File creation Hook correctly installed on pid "+RemoteHooking.GetCurrentProcessId());


            }
            catch (Exception e)
            {
                remoteIf.Log(e.Message);
                remoteIf.Log(e.StackTrace);
                return;
            }

            // Wake up the process
            remoteIf.Log("Waiking up process...");
            RemoteHooking.WakeUpProcess();

            while (true)
            {
                Thread.Sleep(500);

                if (queue.Count > 0)
                {
                    String[] package = null;

                    lock (queue)
                    {
                        package = queue.ToArray();
                        queue.Clear();
                    }

                    remoteIf.OnCreateFile(RemoteHooking.GetCurrentProcessId(), package);
                }
                else
                    remoteIf.Ping();
            }

        }

这是构造函数代码：

public InjectedDLL(RemoteHooking.IContext InContext, String inChannelName)
        {
            // Create the structure which will contain all the messages
            queue = new Stack<string>();
            // Initiate the connection to the Injector process, getting back its interface
            remoteIf = RemoteHooking.IpcConnectClient<IPCInterface>(inChannelName);
            // Try invocating a method to test the connection.
            remoteIf.Ping();
        }

这里有Hook委托和钩子函数

public delegate int CreateFileDelegate(out  IntPtr handle,
            System.IO.FileAccess access,
            ref OBJECT_ATTRIBUTES objectAttributes,
            out IO_STATUS_BLOCK ioStatus,
            ref long allocSize,
            uint fileAttributes,
            System.IO.FileShare share,
            uint createDisposition,
            uint createOptions,
            IntPtr eaBuffer,
            uint eaLength);

        public int CreateFile_Hooked(
            out  IntPtr handle,
            System.IO.FileAccess access,
            ref OBJECT_ATTRIBUTES objectAttributes,
            out IO_STATUS_BLOCK ioStatus,
            ref long allocSize,
            uint fileAttributes,
            System.IO.FileShare share,
            uint createDisposition,
            uint createOptions,
            IntPtr eaBuffer,
            uint eaLength)
        {

            //string s = Marshal.PtrToStringAuto(objectAttributes.ObjectName);
            int res = NtCreateFile(out handle, access,ref objectAttributes,out ioStatus, ref allocSize,fileAttributes, share,createDisposition,createOptions,eaBuffer,eaLength);
            return res;
        }

这里有NtDll.Dll本机函数：

[DllImport("ntdll.dll", ExactSpelling = true, SetLastError = true)]
        public static extern int NtCreateFile(
            out  IntPtr handle,
            System.IO.FileAccess access,
            ref OBJECT_ATTRIBUTES objectAttributes,
            out IO_STATUS_BLOCK ioStatus,
            ref long allocSize,
            uint fileAttributes,
            System.IO.FileShare share,
            uint createDisposition,
            uint createOptions,
            IntPtr eaBuffer,
            uint eaLength);

        [DllImport("ntdll.dll", ExactSpelling = true, SetLastError = true)]
        public static extern int NtOpenFile(
            out  IntPtr handle,
            System.IO.FileAccess access,
            ref OBJECT_ATTRIBUTES objectAttributes,
            out IO_STATUS_BLOCK ioStatus,
            System.IO.FileShare share,
            uint openOptions
            );

        [StructLayout(LayoutKind.Sequential, Pack = 0)]
        public struct OBJECT_ATTRIBUTES
        {
            public Int32 Length;
            public IntPtr RootDirectory;
            public IntPtr ObjectName;
            public uint Attributes;
            public IntPtr SecurityDescriptor;
            public IntPtr SecurityQualityOfService;

        }

        [StructLayout(LayoutKind.Sequential, Pack = 0)]
        public struct IO_STATUS_BLOCK
        {
            public uint status;
            public IntPtr information;
        }

Answer 1

ObjectName是指向UNICODE_STRING结构的指针。托管等价物如下所示：

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
public struct UNICODE_STRING
{
    public ushort Length;
    public ushort MaximumLength;
    [MarshalAs(UnmanagedType.LPWStr)]
    public String Buffer;
}

您需要使用编组来获取结构的托管副本。

var us = Marshal.PtrToStructure<UNICODE_STRING>(objectAttributes.ObjectName);

拥有托管结构后，您可以访问“缓冲区”字段以获取对象的名称。

使用EasyHook从ntdll.dll挂起NtCreateFile API（c＃）

1 个答案: