Massive increase in SPAM in form of user-registration

Countries like China and some parts of middle-east

[Future]

Hello,
We have noticed a massive increase in SPAM specially from China.
Users to tend register on our website/forums and just update there profile with a link to some #*$!/pharmacy/buy viagra or similar kind of SPAM site.

We catch more then 200 user-registrations from same IP and/or same IP ranges many times.

We do not do a email verification now on our websites/forums.
We have a manual question/answer system to avoid auto-bots (we are not using re-captcha or any other kind of captcha mechanism)
Is there anything we can do to avoid this kind of fake registrations ?
Are these auto-bots or someone registering on our website ?

Thanks.

[Elsmarc]

Do email verification and it will all go away. I make my living with forum sites and very rarely have a problem with spammers such as you describe.

Or - If it's China and China doesn't matter to you just block the IPs (or range/block of IPs) it is coming from. Personally I don't block China (or anywhere else) because I get a lot of visitors from China on my sites.

[martinibuster]

I'm not too fond of email verifications. It stops too many legit members who can't spell from joining communities and having joy right now. The more roadblocks you throw in front of a potential new member the likelier, imo, they will not return. I monitor bounced emails and find that the majority are by legit members who mispelled their email addy. Apparently, most of the email addys the non-bot spammers are using are legit. Therefore, in my experience, email verification causes more problems than it solves. That's just my own experience, others may have different experiences/activities on their own communities.

The registration challenges are good, but they don't stop non-bots, which is what I am certain you are seeing. Based on my experience and the kind of posts these members make when they DO post, they're not bots.

I remove the website field altogether. I let people post links in the signature line, that way they have to make a post to have their link show up. This creates an incentive to post. Frivoulous posts and spam posts are dealt with in the usual manner.

I rely on IP banning. I ban IPs as they show up. It's not the ultimate solution but it keeps the spam level to a manageable trickle.

[Future]

We have added few customizations for our forum scripts and run this scripts once every week.

a. We check users signatures for SPAM every week, we find a user idle registration and after several weeks replace with a link in there profile or replace/edit the signature with leaving a link.

We check all signatures for spammylinks once a week and auto-delete them against our db of spam keywords. (a manual review is the only option available for us)