PHP-Nuke <= 7.9 Old-Articles Block "cat" SQL Injection vulnerability

[paisterist@xxxxxxxxxxxxxxxxxxx]

/*
--------------------------------------------------------
[N]eo [S]ecurity [T]eam [NST] - Advisory 31 - 2007-01-13
--------------------------------------------------------
Program: PHP-Nuke
Homepage: http://www.phpnuke.org
Vulnerable Versions: PHP-Nuke <= 7.9
Risk: Medium
Impact: Medium Risk

-==PHP-Nuke <= 7.9 Old-Articles Block "cat" SQL Injection vulnerability==-
---------------------------------------------------------

- Description
---------------------------------------------------------
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.

- Tested
---------------------------------------------------------
localhost & many sites

- Vulnerability Description
---------------------------------------------------------

In /blocks/block-Old_Articles.php the "cat" variable is not sanitized 
correctly. Here is the vulnerable code:

==[ /blocks/block-Old_Articles.php 33-40 ]=========================
if ($categories == 1) {
        $querylang = "where catid='$cat'";
    } else {
        $querylang = "";
        if ($new_topic != 0) {  
            $querylang = "WHERE topic='$new_topic'";
        }
    }
==[ end /blocks/block-Old_Articles.php 33-40 ]=====================


Note that register_globals must be On, because the "cat" variable is not 
defined anywhere. Also, the $querylang variable is 
used after to get some database data:

==[ /blocks/block-Old_Articles.php 49 ]=============================
[...]
$result = $db->sql_query("SELECT sid, title, time, comments FROM 
".$prefix."_stories $querylang ORDER BY time DESC LIMIT $storynum, $oldnum");
[...]
==[ end /blocks/block-Old_Articles.php 49]==========================


Then we have a link that contains the data taken from the database:

==[ /blocks/block-Old_Articles.php 94-97-101]=======================
[...]
$boxstuff .= "<tr><td 
valign=\"top\"><strong><big>&middot;</big></strong></td><td> <a 
href=\"modules.php?name=News&amp;file=article&amp;sid=$sid$r_options\">$title</a>
 $comments</td></tr>\n";
==[ end /blocks/block-Old_Articles.php 94-97-101 ]==================


So, in resume, if we set "categories" var to 1 by the GET method and then we 
set "cat" (also by the GET method) to a malicio
us sql code, we can get easily the admin data with a UNION statement. If you 
don't how to bypass the PHP-Nuke SQL Protection
 just read this advisory: 
http://www.neosecurityteam.net/advisories/PHP-Nuke--7.9-SQL-Injection-and-Bypass-SQL-Injection-Protection-vulnerabilities-27.html

magic_quotes_gpc php directive must be turned Off so the simple quotes (') are 
not filtered. Also we have to know the prefix
 used for the database tables ("nuke_" by default).

==Pseudo-Code Proof of Concept exploit==
<?
/*

Neo Security Team - Pseudo-Code Proof of Concept Exploit
PHP-Nuke <= 7.9 Old-Articles Block "cat" SQL Injection vulnerability

http://www.neosecurityteam.net
Paisterist

*/
set_time_limit(0);
$host="localhost";
$path="/phpnuke/";
$port="80";
$fp = fsockopen($host, $port, $errno, $errstr, 30);

if ($fp) {
    /* we put the GET request on $p variable, with "cid" with the malicious 
code and "categories" set to 1. */

    fwrite($fp, $p);

    while (!feof($fp)) {
        $content .= fread($fp, 4096);
    }

    preg_match("/([a-z0-9]{32})/", $content, $matches);

    if ($matches[0])
    print "<b>Hash: </b>".$matches[0];
}
?>
==Pseudo-Code Proof of Concept exploit==

Whit this PoC code i get the md5 hash of the first admin (God) of the 
nuke_authors table.

- How to fix it? More information?
--------------------------------------------------------

You can found a patch on http://www.neosecurityteam.net/foro/

Also, you can modify the source code adding in the /index.php file some like 
this:

$cat = ($_GET['cat']) ? filter($_GET['cat'], "nohtml") : '';

That's a momentary solution to the problem. I recommend to get the PHP-Nuke 8.0 
version.

- References
--------------------------------------------------------
http://www.neosecurityteam.net/advisories/PHP-Nuke--7.9-Old-Articles-Block-cat-SQL-Injection-vulnerability-31.html
http://www.neosecurityteam.net/advisories/PHP-Nuke--7.9-SQL-Injection-and-Bypass-SQL-Injection-Protection-vulnerabilities-27.html


- Credits
--------------------------------------------------------
Old-Articles Block SQL Injection discovered by Paisterist -> paisterist[dot]nst 
[at] gmail[dot]com

[N]eo [S]ecurity [T]eam [NST] - http://www.neosecurityteam.net/


- Greets
--------------------------------------------------------
HaCkZaTaN, K4P0, Daemon21, Link, 0m3gA_x, NitRic, LINUX, nitrous, m0rpheus, 
nikyt0x, KingMetal, Knightmare and the NST community.

Latinoamerica EXISTS!!

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/* EOF */