Yes that is a blank user name in single quotes and no way to block it using the common names comma separated string. Tried using a double comma in the string but it was edited out. Login attempts are coming hot and heavy forcing me to shut down the site since I cannot access it or login to the back end. Below is an example email from an attempted login.
A user with IP address 200.77.208.178 has been locked out from the signing in or using the password recovery form for the following reason: Used an invalid username '' to try to sign in.
User IP: 200.77.208.178
User hostname: 200.77.208.178.cable.dyn.cableonline.com.mx
Any help blocking this is greatly appreciated.