Millions of sites could be hacked due to flaws in popular WordPress plugins

Pierluigi Paganini March 19, 2021

Experts found vulnerabilities in two WordPress plugins that could be exploited to run arbitrary code and potentially take over a website.

Security researchers disclosed vulnerabilities in Elementor and WP Super Cache WordPress plugins that could be exploited to run arbitrary code and take over a website under certain circumstances.

The flaws were uncovered in the Elementor and WP Super Cache plugin, the former is a website builder plugin with over seven million installs while the latter has over 2 million installs.

Wordfence researchers discovered multiple stored cross-site scripting (XSS) flaws in the Elementor plugin, which collectively received a CVSS score of 6.4.

The lack of server-side validation for HTML tags in Elementor elements (i.e. Heading, Column, Accordion, Icon Box, and Image Box) allows any users to add executable JavaScripts to a post or page via a crafted request.

“Many of these elements offer the option to set an HTML tag for the content within. For example, the “Heading” element can be set to use H1, H2, H3, etc. tags in order to apply different heading sizes via the header_size parameter.” reads the post published by Wordfence. “Unfortunately, for six of these elements, the HTML tags were not validated on the server side, so it was possible for any user able to access the Elementor editor, including contributors, to use this option to add executable JavaScript to a post or page via a crafted request.”

WordPress plugin Elementor

In case an administrator reviewed a post containing malicious JavaScript, its high privileges could be exploited to conduct malicious activities such as creating an administrator, or add a backdoor to the site.

“Since posts created by contributors are typically reviewed by editors or administrators before publishing, any JavaScript added to one of these posts would be executed in the reviewer’s browser,” continues Wordfence. “If an administrator reviewed a post containing malicious JavaScript, their authenticated session with high-level privileges could be used to create a new malicious administrator, or to add a backdoor to the site. An attack on this vulnerability could lead to site takeover.”

The flaws affect versions prior 3.1.2, the developer team behind the plugin added initial patch in version 3.1.2, while additional fixes were included in version 3.1.4.

The research m0ze from the Patchstack Red Team discovered an authenticated remote code execution (RCE) vulnerability in the WP Super Cache that could be exploited by attackers to upload and execute malicious code, potentially resulting in the site takeover.

The flaw affects plugin versions prior 1.7.2.

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Pierluigi Paganini

(SecurityAffairs – hacking, WordPress plugins)

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