In just about every instance of this happening the IP traces back to a range that's been used by spammers/spambots. I'm confident that they're just random auto-attempts to break into accounts, not concentrated attempts trying to exploit an established password weakness or anything. As long as you've got a secure password there's nothing to worry about.
But as I suggested earlier in the thread, if this happens to you please forward any CBR auto-response e-mails to community@comicbookresources.com and we can block those IPs.