Preventing comment spam with math

I came to the realisation yesterday when I posted about Apollo that the spam protection I was using was actually stopping all visitors from leaving comments on my blog. I disabled it for about 12 hours and in that time watched the spam flow in. The solution: Math Comment Spam Protection Plugin

Hopefully everyone’s elementary math is up to scratch. Good thing I didn’t install the “Fourier Transform Comment Spam Protection Plugin” instead 😉

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5 thoughts on “Preventing comment spam with math”

  1. I use the same technique. Works a treat without over-engineering or potentially blocking real folks. I imagine if the technique becomes terribly popular, though, it’ll eventually be worked around.

  2. I always thought Flash would be a good tool to have an authentication box. Not impossible, but it is a much greater pain to disassemble an SWF. Also, with flash focus issues, that has got to make bots more of a pain to utilize too.

  3. If the math method becomes ‘work(ed) around’ because a bot can read the characters 3+6, then simply combine CAPTCHA and math.

    Regarding brushing up on math skills, if one isn’t bright enough to add two single digit numbers, I don’t want them commenting on my blog anyway! 😉

  4. I have been using a similar method in my website for my “Ask Mark” Pod, but instead of mathematical symbols I just ask, What is 4 plus 5. I know they can work round it but so far I haven’t had any spam (cross fingers!)

  5. Thanks for the comments, rest assured the rather simple spam protection method is indeed working. I haven’t received a single unwanted comment in the last 24 hours, but rather refreshingly received 6 that were all interesting reads. No idea what caused my other spam plugin to cease working (I’m guessing it was GD related) but here’s hoping the bots out there don’t learn simple arithmetic anytime soon!

    As for Flash being a possible solution, I’ve seen it on other blogs and I’m sure it would stifle most spam attempts. And Mr. Smith, I agree that this plugin does ensure a certain level of intelligence from those posting comments 😉


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