c++ - 在特定的 Windows DLL 模块中分配内存

Question

我想在进程的特定模块内分配一些内存而不是一般的进程。以下 Windows C++ 代码可以在给定进程 ID 的情况下在进程内分配内存:

#include "pch.h"

#include <windows.h>
#include <winternl.h>
#include <processthreadsapi.h>
#include <iostream>
#include <conio.h>

#pragma comment(lib, "ntdll.lib")

typedef NTSTATUS (NTAPI *nt_alloc_virtual_memory_func)(HANDLE process_handle, PVOID* base_address, ULONG_PTR zero_bits,
                                                       PSIZE_T region_size, ULONG allocation_type, ULONG protect);
typedef NTSTATUS (NTAPI *nt_free_virtual_memory_func)(HANDLE process_handle, PVOID* base_address, PSIZE_T region_size,
                                                      ULONG free_type);

void enable_allocating_executable_memory()
{
    PROCESS_MITIGATION_DYNAMIC_CODE_POLICY mp;
    ZeroMemory(&mp, sizeof mp);
    mp.ProhibitDynamicCode = FALSE;
    SetProcessMitigationPolicy(ProcessDynamicCodePolicy, &mp, sizeof mp);
}

long allocate_memory(char** arguments, const HANDLE process_handle, PVOID process_memory, SIZE_T& allocation_size)
{
    const auto memory_size = arguments[3];
    allocation_size = strtoul(memory_size, nullptr, 10);

    const auto nt_allocate_virtual_memory = reinterpret_cast<nt_alloc_virtual_memory_func>(GetProcAddress(
        GetModuleHandle(L"ntdll.dll"), "NtAllocateVirtualMemory"));

    const auto allocation_status = nt_allocate_virtual_memory(process_handle, &process_memory, 0, &allocation_size,
                                                              MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE);
    if (NT_SUCCESS(allocation_status))
    {
        std::cout << std::hex << process_memory << std::endl;
    }

    return allocation_status;
}

int free_memory(const int argument_count, char** arguments,
                const HANDLE process_handle, SIZE_T& mem_size)
{
    const auto address_string = arguments[3];
    const auto process_address = strtoull(address_string, nullptr, 16);
    auto process_memory_address = reinterpret_cast<PVOID>(process_address);

    if (argument_count < 4)
    {
        return EXIT_FAILURE;
    }

    const auto memory_size = arguments[4];
    mem_size = strtoul(memory_size, nullptr, 10);

    const auto nt_free_virtual_memory = reinterpret_cast<nt_free_virtual_memory_func>(GetProcAddress(
        GetModuleHandle(L"ntdll.dll"), "NtFreeVirtualMemory"));

    const auto status = nt_free_virtual_memory(process_handle, &process_memory_address, &mem_size, MEM_RELEASE);
    return status;
}

int main(const int argument_count, char* arguments[])
{
    if (argument_count < 4)
    {
        return EXIT_FAILURE;
    }

    const auto process_id_string = arguments[1];
    const auto process_id = strtoul(process_id_string, nullptr, 10);

    enable_allocating_executable_memory();

    const auto process_handle = OpenProcess(PROCESS_ALL_ACCESS, FALSE, process_id);
    if (process_handle == nullptr)
    {
        std::cout << "Cannot open process with process id " << process_id << std::endl;
        exit(EXIT_FAILURE);
    }

    const PVOID process_memory = nullptr;
    SIZE_T mem_size;

    const auto command = arguments[2];
    if (strcmp(command, "--allocate") == 0)
    {
        allocate_memory(arguments, process_handle, process_memory, mem_size);
    }
    else if (strcmp(command, "--free") == 0)
    {
        return free_memory(argument_count, arguments, process_handle, mem_size);
    }

    return EXIT_SUCCESS;
}

NtAllocateVirtualMemory 似乎不接受模块的参数。还能用什么？

这背后的原因是，我不希望在分配一些内存后让 jmp 从一个模块转到另一个模块，而是尽可能保留在本地。这也使得 jmp 指令在内存中的大小更短。

Answer 1

I want to allocate some memory inside a specific module

你不能这样做，当模块被映射时，它的内存就被分配了。您无法在模块内部分配内存，模块存在于其分配的页面内，而不存在其他地方。任何分配的页面都将位于模块之外。

或者，如果您想使用已分配但未使用的内存，这称为代码洞。它通常是模块内充满零的内存区域。因此，您可以通过在模块内查找一定长度的冗余零来扫描代码洞，然后可以写入该内存。

此操作经常执行，如果页面设置了执行位，则特别有用，因为您不必更改任何可能被视为有风险的权限。

在使用“分散映射”的注入(inject)器中也经常这样做，它只使用这些代码洞穴来注入(inject)代码。