Security researchers announced on Monday that there had been a supply chain attack on up to 36,000 WordPress plugins running on a wide range of websites that had been backdoored by unknown hackers. Currently, researchers from security firm Wordfence report that the campaign has affected five plugins as of Monday morning. It has been active since last week. It has been reported that unknown threat actors have recently added malicious functionality to plugin updates on WordPress.org, which is the official site for the free open-source WordPress CMS. This update creates an attacker-controlled administrative account that can be used to control the compromised site, as well as add content designed to boost search results. 

The updates can be installed automatically when the updates are installed. There has been a significant amount of backdooring in WordPress plugins to allow malicious code to be injected which can lead to the creation of rogue administrator accounts which can be used for arbitrary purposes. As Wordfence security researcher Chloe Chamberland pointed out in an alert on Monday, the malware injects itself into the system, attempting to create an administrator user account and sending back that account's details to the attacker's server. 

Further, it appears that the threat actor may also have injected malicious JavaScript into the footers of websites, which appears to be causing SEO spam to be displayed throughout the website. According to Wordfence security researchers, a company that monitors the security of the biggest website builder platforms in the world, five plugins have been poisoned with a poisonous patching function so far. Whenever users patch these WordPress plugins, they are presented with a piece of code that creates a new admin account, which is then used by the attackers to establish the account login credentials. 

The perpetrators of this threat (whose identity has not been revealed yet) thus gain full and unrestricted access to the website in this way. The plugins that have been made available are called Social Warfare, BLAZE Retail Widget, Wrapper Link Elementor, and Contract Form 7 Multi-Step Add-on as well as Just Show Hooks. Combined, these five plugins have been installed 36,000 times. Of these, Social Warfare has the most number of installations at 30,000, far and away the most popular one. As of the time of publication, it was not yet clear how the attackers were able to compromise the patching process for these five plugins, and thus compromise their security.

It was reported that reporters at Ars Technica attempted to get in touch with the plugin developers (some did not even provide contact information on their plugin websites, meaning it was impossible to get in touch with them) but did not receive any response. There has been a sharp rise in the number of supply-chain attacks over the past decade, which has become one of the most effective ways to install malware within a supply chain. The threat actors have been able to achieve significant gains by poisoning the software source code so that by simply running a trusted update or installation file, they can infect large numbers of devices. 

This year, an almost disastrous event occurred when a backdoor was discovered, largely through chance, in the widespread open-source XZ Utils code library a week or so ahead of its general release date, narrowly averting disaster. In addition, there have been many other recent supply-chain attacks that can be found in the media. Researchers are currently working on investigating how and why the malware was uploaded to the plugin channel for downloading on the WordPress site to increase their knowledge about it. Several emailed questions were sent to representatives of WordPress, BLAZE, and Social Warfare, none of whom responded. 

Because there is no contact information on the websites of the developers of the remaining three plugins, it was impossible to connect with the representatives of those developers. As mentioned by the Wordfence researchers, they were first made aware of the attack on Saturday when they received an email from a member of the WordPress plugin review team that mentioned the attack. Based on their analysis of the malicious file, the researchers were able to identify four other plugins that had similar codes that were exposed to the same threat. 

There is generally a perception that WordPress is a secure platform for designing and building websites. However, it is a platform with a vast number of third-party themes and plugins, many of which suffer from poor protection, and/or don't enjoy the same level of maintenance as the platform itself. Consequently, they are considered to be a great entry point for threat actors, due to their unique nature. Moreover, the themes and plugins available for WordPress can be both free-to-use and commercially produced, but the latter are often abandoned or maintained by a single developer or hobbyist. 

There is therefore a strong need for WordPress administrators to use extreme caution when installing third-party additions to their websites. They need to ensure that only the files they intend to use are installed. It is imperative for users to ensure their WordPress plugins are always updated and to remain vigilant for any news regarding vulnerabilities. Individuals who have installed any of the compromised plugins should uninstall them immediately and thoroughly inspect their sites for any newly created admin accounts or unauthorized content. Users who utilize the Wordfence Vulnerability Scanner will be alerted if their site is running any of the affected plugins. 

Furthermore, the Wordfence post advises users to monitor their sites for connections originating from the IP address 94.156.79.8, as well as to check for admin accounts with the usernames "Options" or "PluginAuth."