captcha not cutting it

[Cardale]

On my site I use a captcha to attempt and stop spam bots from registering at my site.  So far it has worked fairly well, but I am still getting bots probing and getting through every once in awhile.  I need to beef it up.  Any recommendations?

[jamiet757]

www.recapcha.net

 

It is very simple to integrate, and it works great.

 

http://recaptcha.net/plugins/php/

this will help you integrate it

[Cardale]

I remember reading something about this one being beaten by bots as well.

[jamiet757]

I don't know, I am sure there are some bots out there that can get around anything, but I would say there are very few that could defeat recaptcha. I still think it is your best bet, even though some bots might slip through.

[fbemo]

There are some people offering services to beat captcha, they sell the captcha images

and using iMacors to by pass it.

[Cardale]

Any other ideas?

[oni-kun]

Any other ideas?

 

Any captcha is crackable. Use recaptcha's API to create something complex, or , Oh WHAT!? add a "What is x + x?" question. That'll automatically invalidate every bot who can crack the previous captcha. It's not that hard.

[PFMaBiSmAd]

Text based math questions are already being solved by one simple line of php code using eval() to parse the equation. Even trying to be clever and using the 'word' form of operators and numbers (plus, add, subtract, minus, times, one, two, three...) can be solved by using a simple array replace followed by an eval() statement.

 

However, by outputting the math question as a word problem in a dynamically generated image (even if there is no background noise in the image) makes finding and solving the math question significantly harder (it is fairly easy to use OCR to find 4-6 letters/numbers in an image, but it is much harder to read and parse a complete sentence from an image.)