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  Обход функции ip2long в PHP (protection bypass)

From:rgod_(at)_autistici.org <rgod_(at)_autistici.org>
Date:2 августа 2006 г.
Subject:PHP ip2long() function circumvention

--- PHP ip2long() function circumvention --------------------------------------

tested on php 5.0.2
          "  4.3.3

after some test on miniBB application (http://www.minibb.net/) I obtained that
the php ip2long() function can be tricked to return a valid IPv4 Internet
network address instead of "-1" even if the ip address argument is not a valid
one, through the injection of some chars, ex:

for ($i=0; $i<=255; $i++)
 echo $i.":".ip2long("".chr($i).

when chr($i) is chr(0), chr(9), chr(10), chr(11), chr(12), chr(13) or chr(32)

it gives the following (valid) result:


in minibb case this could result in sql injection, forging an header like this:


or even like this:


(however Minibb limit the string to 15 chars so you will have an unuseful twelve
chars sql injection...)
also remeber that HTTP headers is not filtered by PHP magic_quotes_gpc, so this
could give an attacker the way to fully compromise an application

code taken from MiniBB 2.0
index.php, 248-264
/* Banned IPs/IDs stuff */
$thisIp=getIP();                      <--------------------- here $thisIp becomes our sql code
$cen=explode('.', $thisIp);

if(isset($cen[0]) and isset($cen[1]) and isset($cen[2])){
else {

if (db_ipCheck($thisIp,$thisIpMask,$user_id)) { //<-----------  $thisIp is passed to the db_ipCheck() function
$title=$sitename." :: ".$l_accessDenied;
echo ParseTpl(makeUp('main_access_denied')); exit;

bb_functions.php, near lines 123-131
function getIP(){
if ($ip2!='' and ip2long($ip2)!=-1) $finalIP=$ip2; else $finalIP=$ip1; //<-- vulnerable code
return $finalIP;


setup_mysql.php, near lines 99-105:

function db_ipCheck($thisIp,$thisIpMask,$user_id){
$res=mysql_query('select id from '.$GLOBALS['Tb'].' where
banip='."'".$thisIp."'".' or banip='."'".$thisIpMask[0]."'".' or //<--- sql injection
banip='."'".$thisIpMask[1]."'".' or banip='."'".$user_id."'");
echo mysql_error();
if($res and mysql_num_rows($res)>0) return TRUE; else return FALSE;


1.05 29/07/2006

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