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

#define SIZE 0x100

void print_mem(BYTE *mem)
{
    int i;
    for (i=0; i<SIZE; i++)
        printf("%02x ", mem[i]);
    printf("\n");
}


int main(int argc, char *argv[])
{
    BYTE *mem;
    int i;

    mem = VirtualAlloc(NULL, SIZE, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
    printf("Allocated memory at %08x...\n", mem);

    for (i=0; i<SIZE; i++)
        mem[i] = '\xff';

    __try {
        mem[30] = 0x31; // xor eax, eax
        mem[31] = 0xc0;

        mem[32] = 0xbf; // mov edi, mem
        *((DWORD*)&mem[33]) = (DWORD)mem;

        mem[37] = 0xb9; // mov ecx, SIZE
        *((DWORD*)&mem[38]) = SIZE;

        mem[42] = 0xf3; // rep stosd
        mem[43] = 0xaa;

        printf("Shellcode written...\n");

        __asm {
            mov eax, mem
            add eax, 30
            jmp eax
        }

    } __except(1) {
        printf("\nCrash.\n");
        print_mem(mem);
    }

    return 0;
}