What you described is not hacking. It is simple dictionary attack using known username and password.
As far as I know from reading about mcxNow, they are pretty good in security. I am an Information Security Specialist worked in this field for over 25 years (Penetration Testing (Hacking) is one of my main skillset), my clients includes all the big banks, government and other blue chip company listed in stock market around the world. Not to mention, I designed the security for Google Data Centre in 2 different location in the globe.
Most site are attack by SQL injection, Code injection, and open ports which have Admin privilege. They are not using SQL, Java, PHP, ASP, and other potential vulnerable code. From how they described their Web Application operation. It is very good in security. That is why I also use mcxNow, to put my BTC in their system.
The only way to attack C++ is normally Buffer Overflow, then inject code. But this have to be done locally on the actually server physically in front of you. Therefore no hacker on the Internet should be able to do this vulnerability and exploit it.
Anyway good day. I said my piece.
Dragonkid