clod81 / dinvoke

Dynamically invoke arbitrary unmanaged code from managed code without P/Invoke.

D/Invoke

Fork of D/Invoke by TheWover, but refactored to .NET Standard 2.0 and split into individual NuGet packages.

Why?

The aim of this project is to provide D/Invoke in a more minimalist form. It only contains the core DynamicInvoke and ManualMap functionality, without all the additional helper methods and delegates. This help keeps the packages small and lowers the detection surface for AV.

Examples

DynamicApiInvoke

Define the delegates and any strucs/enums that you need. Some common ones are provided in the DInvoke.Data namespace.

[UnmanagedFunctionPointer(CallingConvention.StdCall)]
private delegate Data.Native.NTSTATUS NtOpenProcessDelegate(
    out SafeProcessHandle processHandle,
    Data.Win32.WinNT.ACCESS_MASK desiredAccess,
    Data.Native.OBJECT_ATTRIBUTES objectAttributes,
    CLIENT_ID clientId);

private struct CLIENT_ID
{
    public IntPtr UniqueProcess;
    public IntPtr UniqueThread;
}

Initialise the parameters and bundle them into an object[].

var handle = new SafeProcessHandle();
var oa = new Data.Native.OBJECT_ATTRIBUTES();
var cid = new CLIENT_ID { UniqueProcess = 1234 };

object[] parameters = [ handle, Data.Win32.WinNT.ACCESS_MASK.MAXIMUM_ALLOWED, oa, cid ];

Call DynamicApiInvoke specifying the DLL name, the API name, the delegate, and the function parameters. The output data type is specified as a generic, T. Most NT APIs return a type of NTSTATUS, which is a uint.

var status = DynamicInvoke.Generic.DynamicApiInvoke<uint>(
    "ntdll.dll",
    "NtOpenProcess",
    typeof(NtOpenProcessDelegate),
    ref parameters);

Parameters marked as out need to be read out of the parameters array and cast back onto the original variable.

handle = (SafeProcessHandle)parameters[0];

Function Hashing

Use a tool such as CSharpRepl to import DInvoke.DynamicInvoke.dll. Call Utilities.GetApiHash to generate a hash for the desired DLL name and API.

> #r "C:\Tools\DInvoke\DInvoke.DynamicInvoke\bin\Debug\netstandard2.0\DInvoke.DynamicInvoke.dll"

> DInvoke.DynamicInvoke.Utilities.GetApiHash("ntdll.dll", 0x123456789)
"9BC00C9AC691986FE3CEEDA6E12F9FB0"

> DInvoke.DynamicInvoke.Utilities.GetApiHash("NtOpenProcess", 0x123456789)
"9713035EC6AE7BB32303F84822AB80AA"

Use GetLoadedModuleAddress to resolve the address of the DLL and GetExportAddress to resolve the address of the target function.

var hModule = DynamicInvoke.Generic.GetLoadedModuleAddress(
    "9BC00C9AC691986FE3CEEDA6E12F9FB0", // ntdll.dll
    key);

var hPointer = DynamicInvoke.Generic.GetExportAddress(
    hModule,
    "9713035EC6AE7BB32303F84822AB80AA", // NtOpenProcess
    key);

The rest of the steps are the same as above, but we call DynamicFunctionInvoke instead.

var status = DynamicInvoke.Generic.DynamicFunctionInvoke<uint>(
    hPointer,
    typeof(NtOpenProcessDelegate),
    ref parameters);