Pierluigi Paganini March 26, 2020

Crooks behind the WordPress WP-VCD malware are distributing pirated versions of the Coronavirus plugins that inject a backdoor into websites.

behind the WordPress WP-VCD malware are distributing pirated versions of the Coronavirus plugins that inject a backdoor into websites

The malware was first spotted in July 2017 by the Italian security expert Manuel D’Orso who noticed that the malicious code was loaded via an include call for the wp-vcd.php file and injected malicious code into WordPress core files such as functions.php and class.wp.php.

The wp–vcd malware attacks continued, evolving across the months. In November 2017, researchers from Sucuri firm discovered a new strain of this malware that injected malicious code in the legitimate files of the two the default themes “twentyfifteen” and “twentysixteen”included in the WordPress CMS in 2015 and 2016.

In November 2019, experts reported a highly active malicious campaign that was infecting WordPress sites with a malware dubbed WP-VCD that injects a backdoor into any themes that are installed on the site as well as various PHP files.

The WP-VCD malware also attempt to compromise other sites on the same shared host. The compromised websites are used to display popups or to implements traffic direction systems.

Researchers at MalwareHunterTeam and BleepingComputer researchers found WordPress plugins named “COVID-19 Coronavirus – Live Map WordPress Plugin”, Coronavirus Spread Prediction Graphs”, and “Covid-19” that shared a malicious intent.

The plugins contained a ‘class.plugin-modules.php’ file that contained malicious code and various base64 encoded strings that are commonly associated with WP-VCD malicious plugins.

“These WordPress plugins and another one we found were zip files containing what appeared to be legitimate commercial plugins named “COVID-19 Coronavirus – Live Map WordPress Plugin”, Coronavirus Spread Prediction Graphs”, and “Covid-19″.” reported Bleepingcomputer.

“we found that all of these plugins contained a ‘class.plugin-modules.php‘ file that contained malicious code and various base64 encoded strings that are commonly associated with WP-VCD plugins.”

Once the plugin is installed, it will take the base64 encoded PHP code in the WP_CD_CODE variable and save it to the /wp-includes/wp-vcd.php file.

Then it prepends code to the /wp-includes/post.php file to allow the automatic load of the wp–vcd.php every time a page is loaded on the site.

The malicious plugin will inject a base64 encoded PHP code to each functions.php of the installed themes.

Upon these changes, the WP-VCD malicious code will connect to the C2 server to receive commands to execute on the WordPress host.

To avoid being infected with the WP-VCD malware experts recommend to avoid downloading pirated WordPress plugins from untrusted sources.

“It is strongly advised that you only install WordPress plugins from authorized sites and do not install any pirated plugins as there is a good chance your site will become compromised.” concludes Bleeping Computer.

Pierluigi Paganini

(SecurityAffairs – WordPress, Coronavirus)

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