SPAM: fighting back

Over the last two months or so there has been a surge of comment spam on this very blog. It has come to the point where I have been erasing 200 email notifications for comments on GeoLand; all of them for Viagra and other exotic drugs.

The time has come to step up and do something about it. I wanted a solution that is easy to install and does the job right. Reading a few blog posts on other wordpress blogs that have had similar problems I decided to give Math Comment Spam a go. At a 4Kb download and 2 minute install instructions its not bad of a solution.

I just dropped the two php files of the zip file in a subfolder of my plugins directory (/wp-content/plugins/), enabled it, and dropped a small piece of code in my comments.php file and I was ready to go. Now spammers have to physically take a look at the form and solve a very elaborate math problem which might discourage them a bit, since now the whole process stops being automated (using automated spam bots).

While on the subject I have to note that while looking personally at all these comment notifications I might have missed a few good posts. If you don't see a legitimate post of yours left whithin the last two months, I apologize; please post again.

UPDATE (sep 16th): the math comment plugin does really work !!! I have actually received only one spam message in a period of more than a week, while in the past I had to go through hundreds of spam messages daily to see if there was any legit among them.

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11 Comments

this plug-in is very good but need some more features like for the error handling (post something within IE with the wrong sum).

I modified the plugin to get written numbers because after a while the comment spam was not over :(

SPAM: fighting back...

Comment spam is a big problem for every blog owner, while a lot of spam is send to the trackback URI is there also a lot of spam send directly to the comment form. This article gives a good idea how to prevent spam using the wordpress plugin "Math Com...

Well might seem like a good idea but it's very easy to bypass.
Just read up on parsing text, the bot could easily find 3 + 4, calculate it without any hussle and pass it into the text field.

It's just a matter of time before this will not work anymore.

Yes, spam is a big problem now. I add to my forum captcha for registration, and now I have changed url to nofollow in posts. On blogs it looks similar. Sometimes I have problem to solve these complicated math tools, but it is necessary protection on spam now.

Thanks for the link, will give that a bash. I had the same problem with Joomla content management system - managed to get a CAPCHA form plugin for that, and the spam went away - for now. These math sum checkers seem really good.

Absolutely spam is a global problem not only for search engines but for people who use mail.

Seacrh engines like Google and Yahoo are overfilled by spam. What will be the next?

well after having read your entry I wonder if automated spam is the main source of the spam you used to receive, since if it is, the spma filter you added is useful, but if it is not, I agree with others when sayign that it's a matter of time before viagra comment notifications appear. However this entry is from september 2007.... have it worked well?