When the bots attack! [closed]

Question

What are some popular spam prevention methods besides CAPTCHA?

Answer 1

Invisble form fields. Make a form field that doesn't appear on the screen to the user. using display: none as a css style so that it doesn't show up. For accessibility's sake, you could even put hidden text so that people using screen readers would know not to fill it in. Bots almost always fill in all fields, so you could block any post that filled in the invisible field.

Answer 2

I have tried doing 'honeypots' where you put a field and then hide it with CSS (marking it as 'leave blank' for anyone with stylesheets disabled) but I have found that a lot of bots are able to get past it very quickly. There are also techniques like setting fields to a certain value and changing them with JS, calculating times between load time and submit time, checking the referer URL, and a million other things. They all have their pitfalls and pretty much all you can hope for is to filter as much as you can with them while not alienating who you're here for: the users.

At the end of the day, though, if you really, really, don't want bots to be sending things through your form you're going to want to put a CAPTCHA on it - best one I've seen that takes care of mostly everything is reCAPTCHA - but thanks to India's CAPTCHA solving market and the ingenuity of spammers everywhere that's not even successful all of the time. I would beware using something that is 'ingenious' but kind of 'out there' as it would be more of a 'wtf' for users that are at least somewhat used to your usual CAPTCHAs.

Answer 3

The most common ones I've observed orient around user input to solve simple puzzles e.g. of the following is a picture of a cat. (displaying pictures of thumbnails of dogs surrounding a cat). Or simple math problems.

While interesting I'm sure the arms race will also overwhelm those systems too.

Answer 4

Try Akismet

Captchas or any form of human-only questions are horrible from a usability perspective. Sometimes they're necessary, but I prefer to kill spam using filters like Akismet.

Akismet was originally built to thwart spam comments on WordPress blogs, but the API is capabable of being adapted for other uses.

Update: We've started using the ruby library Rakismet on our Rails app, Yarp.com. So far, it's been working great to thwart the spam bots.

Answer 5

Block access based on a blacklist of spammers IP addresses.

Answer 6

Mollom is supposedly good at stopping spam. Both personal (free) and professional versions are available.