Spam user registration . but no spam links

What is this bot up to?

[physics]

I just got a new registration on one of my phpBB sites. The username sounded fishy so I searched it in google. Up came tons of registrations, many from in the past few days, none with any posts. Weird thing is that there were no spam posts, no spam urls in the profile (excecpt one linking to the ICQ profile for this 'bot' but there didn't seem to be anything on that profile that would be profitable), no spam sticky mails, nothing. So what is this bot up to?
Is the plan to register to tons of boards, see which ones don't remove their username and then spam those to the max in a week?
Or is it to wait a while and then change the profile url (this way hopefully avoiding scrutiny)?
Or is someone just testing their bot?
In any case they were effective in taking all of the top spots in google for this weird word, maybe that was the goal?

[camweh]

Sounds like it's much the same as mentioned in this topic:
[webmasterworld.com...]

A sleeper?

[physics]

Thanks camweh, that looks like the same thing.

The newer versions of phpbb have the graphic number requirement for users registering that will stop this.

Note that this version of phpBB was the newest release available as of about a week ago, with captchas turned on, so the 'number requirement' did not stop things. Probably should take trillianjedi's advice and change the file names but my issue is that will just make upgrading and installing mods harder. Maybe I'll add another captcha type thing to the registration form, like "What is 2+3?", just to slow down these sort of bots.

[camweh]

I turned off Visual Confirmation over three months ago because it wasn't stopping them. I've added the VIP-code MOD. The code is right there on the registration page but they have to be able to read to know what to look for ;-)
To date no bots.

[rogerd]

Unfortunately, image verification seems to be tougher to make effective. I'm seeing quite a bit of blog spam despite an image verification requirement. When I first installed it, the spam stopped like a closed faucet.

[physics]

I installed an alternate 'textual confirmation' mod that allows you to make up your own questions and acceptable answers. This way unless your forum is so popular that people will specifically target it then you should be safe. Even in that case you can change the questions and answers as often as you want from the admin.
[bbantispam.com...]