spot blog: Captcha Wars

March 16, 2006

Captcha Wars

I have a spam problem. Not just in my email, where we use SpamAssassin on the server combined with Firefox's Bayesian filter in my client, but in my blog comments and in the public forums I run on my web pages. Sadly the net is rife with spambots searching for forms they can fill in, creating comments with links to their master's webpages in order to boost their google-rank.

I first tried to defend myself by using a filter of spam URLs that was collaboratively maintained. No matter how often I updated the db and how often I added my own patterns to it, I couldn't keep up with spam in my blog. It came in piles, 20 at a time.

I then switched to a Captcha, a puzzle or question that is difficult for a robot to answer. Most are based on vision or reading, making them a problem for the visually impaired, but that's a whole nother story. The good news is the spam stopped... for a while. It seems the robots had learned to decode the aberration to the text introduced by the captcha. I altered the code to do something different, but the spam came back. I altered it again to the point where it's difficult for a person to read. This game of cat and mouse has played out over months and years that I have run this blog. Captcha Wars are going on all over the internet.

And now the spam is back again, about one per day. It's different than it used to be though, now instead of batches of similar messages it's just one or two. At this point I suspect a sweatshop. Posted by spot at March 16, 2006 12:12 PM

Comments

Spam sucks. If you're willing to make a switch of platform, WordPress is very good for defending spam. I won't say it's the most amazing piece of software known to man as I do have my gripes, but they've done pretty good on the spam front. On my blog I'm running WP 1.5 with the Spam Karma plugin which does a pretty grand job. Akismet has had quite a lot of buzz too but I've not tried it so can't comment. And jeeezaz... that CAPTCHA is crazy difficult to read. Posted by: Jon Leighton at March 16, 2006 01:55 PM