On December 18th,  the security experts at WordFence were probably going crazy when their system alarms alerted them of an unusual number of WordPress attacks going on. In fact, WordFence had not seen such a volume of attacks like this before.

The infrastructure at WordFence was scaled up and is now monitoring what appears to be the most aggressive distributed brute force attack in history, targeting WordPress websites. The WrodFence team announced it was witnessing more than 14.1 million attacks per hour.
As WordFence published details on the WordFence.com blog which goes over the reasons for this unprecedented attack volume and what you can do to protect from the attack.. Of course, WordFence continues to keep an eye on the matter.