Just FYI - this started happening to in February. Spammers are just automatically running down the lists of users on web communities and trying crude brute force attacks hoping to gain access to the user accounts in order to spam links to the users. In the extremely unlikely event your password is so weak that a common password generator gets it in less than 5 attempts, they would then attempt to spam links to other forum members. That would not work because of limitations on how many members can be sent a message at one time. Out of all the complaints from web forums I've seen about the nuisance, I have yet to see anyone complain about an actual successful attempt. The 5 attempt limitation exists specifically to combat stuff like this, because it's unlikely a human would sit there and repeatedly fail to login in a matter of seconds or minutes.
There are a whole bunch of countries banned at the server level in addition to hundreds and hundreds of specific IPs, but that's really pretty much pointless. Obviously the originations of the login attempts are not really jumping from country to country all over the globe by the second.
Just keep a strong password and don't worry about it. If your password is "password"...reset it.