CryptoPHP is a threat that uses backdoored Joomla, WordPress and Drupal themes and plug-ins to compromise webservers on a large scale, and Fox-It warns that site administrators are at risk of being socially engineered into installing the backdoor on their server. By publishing pirated themes and plug-ins free for anyone to use instead of having to pay for them, the CryptoPHP actor is social engineering site administrators into installing the included backdoor on their server.

Fox-It warns that after being installed on a webserver the backdoor has several options of being controlled which include command and control server communication, mail communication as well as manual control.

Operators of CryptoPHP currently abuse the backdoor for illegal search engine optimization, also known as Blackhat SEO. The backdoor is a well developed piece of code and dynamic in its use. The capabilities of the CryptoPHP backdoor include integration into popular content management systems like WordPress, Drupal and Joomla; public key encryption for communication between the compromised server and the command and control (C2) server; an extensive infrastructure in terms of C2 domains and IP’s; backup mechanisms in place against C2 domain takedowns in the form of email communication; manual control of the backdoor besides the C2 communication; remote updating of the list of C2 servers and the ability to update itself.

Fox-It says it has identified thousands of backdoored plug-ins and themes which contained 16 versions of CryptoPHP as of the 12th of November 2014.

Fox-It has produced a white paper that details how to detect the presence of the backdoor.