Security Experts:

Connect with us

Hi, what are you looking for?



Unpatched WPBakery WordPress Plugin Vulnerability Increasingly Targeted in Attacks

The Wordfence team at WordPress security company Defiant warns of an increase in attacks targeting an unpatched vulnerability in the Kaswara addon for the WPBakery Page Builder WordPress plugin.

The Wordfence team at WordPress security company Defiant warns of an increase in attacks targeting an unpatched vulnerability in the Kaswara addon for the WPBakery Page Builder WordPress plugin.

Tracked as CVE-2021-24284 (CVSS score of 10) and disclosed in April 2021, the critical-severity security bug allows an unauthenticated attacker to upload malicious PHP files to a vulnerable site, potentially achieving remote code execution.

According to Wordfence, an attacker can exploit the flaw to inject malicious JavaScript code into any file on the WordPress installation and completely take over a vulnerable site.

When discovered, the flaw was being actively exploited, and Wordfence warned WordPress website administrators that the plugin had been closed without a patch, urging them to remove it immediately.

Although more than a year has passed since the zero-day was disclosed, between 4,000 and 8,000 sites continue to use the plugin, which exposes them to malicious attacks.

Over the past two weeks, Wordfence has seen a massive surge in the number of attack attempts targeting the vulnerability, at an average of 440,000 per day. The attacks come from 10,215 attacking IP addresses, with five IP addresses being responsible for the majority of assaults.

The attackers, Wordfence explains, are probing more than 1,5 million WordPress sites for the vulnerable plugin, but the vast majority of them are not impacted, given that they do not use the plugin.

“The majority of the attacks we have seen are sending a POST request to /wp-admin/admin-ajax.php using the uploadFontIcon AJAX action found in the plugin to upload a file to the impacted website. Your logs may show the following query string on these events: /wp-admin/admin-ajax.php?action=uploadFontIcon HTTP/1.1,” Wordfence says.

Most of the attacks attempt to upload a .ZIP archive containing a malicious PHP file that is extracted to the /wp-content/uploads/kaswara/icons/ directory, and which allows the attackers to deploy additional payloads.

Wordfence has noticed the use of the NDSW trojan in some of these attacks. The trojan can inject code into legitimate JavaScript files and can be used to redirect users to malicious domains.

“At this time the plugin has been closed, and the developer has not been responsive regarding a patch. The best option is to fully remove the Kaswara Modern WPBakery Page Builder Addons plugin from your WordPress website,” Wordfence notes.

Related: Exploited Vulnerability Patched in WordPress Plugin With Over 1 Million Installations

Related: Critical Code Execution Flaws Patched in ‘PHP Everywhere’ WordPress Plugin

Related: Critical Flaw Impacts WordPress Plugin With 1 Million Installations

Written By

Ionut Arghire is an international correspondent for SecurityWeek.

Click to comment

Expert Insights

Related Content


Zendesk is informing customers about a data breach that started with an SMS phishing campaign targeting the company’s employees.


The release of OpenAI’s ChatGPT in late 2022 has demonstrated the potential of AI for both good and bad.


The FBI dismantled the network of the prolific Hive ransomware gang and seized infrastructure in Los Angeles that was used for the operation.

Malware & Threats

Microsoft plans to improve the protection of Office users by blocking XLL add-ins from the internet.

Cloud Security

VMware vRealize Log Insight vulnerability allows an unauthenticated attacker to take full control of a target system.


A new study by McAfee and the Center for Strategic and International Studies (CSIS) named a staggering figure as the true annual cost of...

IoT Security

Lexmark warns of a remote code execution (RCE) vulnerability impacting over 120 printer models, for which PoC code has been published.

Mobile & Wireless

Apple rolled out iOS 16.3 and macOS Ventura 13.2 to cover serious security vulnerabilities.