100,000 WordPress sites using the Contact Form 7 Datepicker plugin are exposed to hack

Pierluigi Paganini April 03, 2020

An authenticated stored cross-site scripting (XSS) vulnerability could allow attackers to create rogue admins on WordPress sites using Contact Form 7 Datepicker plugin.

Administrators of WordPress sites using the Contact Form 7 Datepicker plugin are recommended to remove or deactivate it to prevent attackers from exploiting a stored cross-site scripting (XSS) vulnerability to create rogue admins or taking over admin sessions.

The ‘Contact Form 7 Datepicker‘ is open-source software that allows adding a date field to the user interface of the Contact Form 7 WordPress plugin, which is a contact form management plugin currently used on over 5 million websites. The plugin was installed on more than 100k WordPress sites using the Contact Form 7 Datepicker plugin. The flaw was discovered by researchers from the Wordfence Threat Intelligence team.

“On April 1, 2020, the Wordfence Threat Intelligence team discovered a stored Cross Site Scripting (XSS) vulnerability in Contact Form 7 Datepicker, a WordPress plugin installed on over 100,000 sites.” reported the analysis published by WordFence. “As the plugin developer’s github page indicated that the plugin was no longer being maintained, we contacted the WordPress plugins team with our disclosure, and they immediately removed the plugin from the repository for review. “

The plugin has been closed on April 1, 2020, and is no more available for download. Its contributors and developers confirmed that it will be no longer maintained and it will be definitively removed from the WordPress repository.

The Contact Form 7 Datepicker plugin allows users to add a datepicker to forms generated by Contact Form 7. The plugin also allows the users to modify settings for these datepickers.

“In order to process these settings, it registered an AJAX action calling a function that failed to include a capability check or a nonce check. As such, it was possible for a logged-in attacker with minimal permissions, such as a subscriber, to send a crafted request containing malicious JavaScript which would be stored in the plugin’s settings.” continues the analysis.

“The next time an authorized user created or modified a contact form, the stored JavaScript would be executed in their browser, which could be used to steal an administrator’s session or even create malicious administrative users.”

Admins of websites using the flawed plugin should search for an alternative to use on their websites.

Unfortunately, the number of attacks attempting to exploit vulnerabilities in WordPress plugins continues to increase.

A few weeks ago researchers at NinTechNet reported an ongoing campaign that was actively exploiting a zero-day flaw in the WordPress Flexible Checkout Fields for WooCommerce plugin. Other attacks recently observed are:

  • Jan. 2020 – An authentication bypass vulnerability in the InfiniteWP plugin that could potentially impact by more than 300,000 sites.
  • Jan. 2020 – Over 200K WordPress sites are exposed to attacks due to a high severity cross-site request forgery (CSRF) bug in Code Snippets plugin.
  • Feb. 2020 – A serious flaw in the ThemeGrill Demo Importer WordPress theme plugin with over 200,000 active installs can be exploited to wipe sites and gain admin access to the site.
  • Feb. 2020 – A stored cross-site vulnerability in the GDPR Cookie Consent plugin that could potentially impact 700K users.
  • Feb. 2020 – A zero-day vulnerability in the ThemeREX Addons was actively exploited by hackers in the wild to create user accounts with admin permissions.
  • March 2020 – The WordPress plugin ‘ThemeREX Addons’ is affected by a critical vulnerability that could allow remote attackers to execute arbitrary code.
  • March 2020 – Flaws in the Popup Builder WordPress plugin could allow unauthenticated attackers to inject malicious JavaScript code into popups of 100K+ websites.
  • March 2010 – A critical privilege escalation flaw in the WordPress SEO Plugin – Rank Math plugin can allow registered users to gain administrator privileges.

I believe it is very important to protect WordPress install with dedicated solutions, I’m currently using WordFence solution, the company provided with a license to evaluate the premium features.

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Pierluigi Paganini

(SecurityAffairs – Contact Form 7 Datepicker, wordpress)

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