Over 1,000 WordPress Sites Infected with JavaScript Backdoors Enabling Persistent Attacker Access
Mar 06, 2025
Data Breach / Website Security
Over 1,000 websites powered by WordPress have been infected with a third-party JavaScript code that injects four separate backdoors. "Creating four backdoors facilitates the attackers having multiple points of re-entry should one be detected and removed," c/side researcher Himanshu Anand said in a Wednesday analysis. The malicious JavaScript code has been found to be served via cdn.csyndication[.]com. As of writing, as many as 908 websites contain references to the domain in question. The functions of the four backdoors are explained below - Backdoor 1, which uploads and installs a fake plugin named "Ultra SEO Processor," which is then used to execute attacker-issued commands Backdoor 2, which injects malicious JavaScript into wp-config.php Backdoor 3, which adds an attacker-controlled SSH key to the ~/.ssh/authorized_keys file so as to allow persistent remote access to the machine Backdoor 4, which is designed to execute remote commands and fetches anot...