Dozens of plug-ins for the widely used open source web blogging software WordPress are now offline after a backdoor was discovered in them, used to push malicious code to any website that relied on the plug-ins. The backdoor was discovered after a new corporate owner bought these plug-ins.

Anchor Hosting founder Austin Ginder sounded the alarm in a blog post last week describing a supply chain attack on a WordPress plug-in maker called Essential Plugin. Ginder said someone last year bought Essential Plugin and the backdoor was soon added to the plug-ins’ source code. The backdoor sat dormant until earlier this month when it activated and began distributing malicious code to any website with the plug-ins installed.

Essential Plugin says on its website that it has over 400,000 plug-in installs and more than 15,000 customers. WordPress’ plug-in install page says the affected plug-ins are in over 20,000 active WordPress installations.

Plug-ins allow owners of WordPress-based websites to extend the site’s functionality, but in doing so grant the plug-ins access to their installations, which can open these websites to malicious extensions and potential compromise. But Ginder warned that WordPress users are not notified of any plug-ins’ change in ownership, exposing users to potential takeover attacks by their new owners.

According to Ginder, this is the second hijack of a WordPress plug-in discovered in as many weeks. Security researchers have long warned of the risks of malicious actors buying software and changing its code in order to compromise a large number of computers around the world.

While the plug-ins have been removed from WordPress’ directory and now list their closure as “permanent,” Ginder warned that WordPress owners should check if they still have one of the malicious plug-ins installed and remove it. Ginder has a list of the affected plug-ins in the blog post.

Representatives for Essential Plugin did not respond to a request for comment.

Topics

cyberattack, cybersecurity, Security, supply chain, WordPress

Zack Whittaker

Security Editor

Zack Whittaker is the security editor at TechCrunch. He also authors the weekly cybersecurity newsletter, this week in security.

He can be reached via encrypted message at zackwhittaker.1337 on Signal. You can also contact him by email, or to verify outreach, at zack.whittaker@techcrunch.com.

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Someone planted backdoors in dozens of WordPress plug-ins used in thousands of websites