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Can a CSRF CAPTCHA be defeated?

Is it to possible break captcha? If yes, how? If no, why websites use difficult captcha systems?

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You might want to try searching for existing CAPTCHA questions to see if any fit your inquiry. Particularly this one may be of interest. – Iszi Aug 9 '12 at 18:24

marked as duplicate by Rory Alsop♦ Aug 9 '12 at 18:47

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

2 Answers

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Yes. CAPTCHA is broken and I have actually used software that breaks it.

I forget the toolkit. Its on my laptop and I'm at work right now but I just googled and found this one http://code.google.com/p/captcha-breaker/

There have been some successful attacks against reCAPTCHA as well but I think they have been mitigated.

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Yes. The most foolproof method is using humans for low wages, who will break ~1000 CAPTCHAs for ~$2. Certain CAPTCHAs have been broken at various times (though they often get upgraded to become more difficult), but still present a difficult barrier for spammers (who often will go to easier targets instead).

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What about AES? For low wadges, they could be researching and analysing like NSA. Or factoring keys using scientific calculators with wifi. When human decision making makes difference, why not. – Andrew Smith Aug 9 '12 at 21:04
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@AndrewSmith - that made absolutely no sense. AES (Advanced Encryption Standard) is a symmetric encryption cipher. It has nothing to do with CAPTCHAs or presenting a barrier to spammers. – dr jimbob Aug 9 '12 at 21:24
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@drjimbob By this point I'm relatively sure that Andrew is just a neural net with a string generator attached. SELECT * FROM words WHERE meaning ~= subject ORDER BY RAND() – Polynomial Aug 10 '12 at 5:53

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