List of weakness
hn free CAPTCHA
This is a free php-class for generating CAPTCHA-images, found at http://www.nogajski.de/horst/php/captcha/. This is one of the free CAPTCHA scripts from great service phpclasses.org, but unfortunately this class is not as great as service. Well, all I want to say is that many CAPTCHA-creators thinks that getting a lot of ttf-fonts, and spinnig letters with different colors is enough to create good CAPTCHA. And, for sure, this approach is easy to implement - writing lettes with ttf-font in different angle is the only font operation which GD PHP library allows. So, why this CAPTCHA is weak? Because a lot of fonts plus turned letters NOT EQUAL good CAPTCHA. Color model is ugly, anyone believes that it's hard to sepatare lettes from background? Writing OCR for this CAPTCHA is only a task of getting correlational masks for each letter (0-9A-F = 16) for each font. A task for one evening.
rapidshare.de
This CAPTCHA appears when trying to download something from rapidshare.de without premium account. It's the only real obstacle to make an automated downloader, which was made (rapidleech, etc) not once for prevoius versions of their CAPTCHA, but this one still was not breaked. But it's easy! This captcha of course can be cracked and breaked due to poor color management. Guys who made it decided to defence against the OCR which is intended to recongnize a normal text, not CAPTCHA. But if the task is to break exactly this CAPTCHA - no problem! By the way, author of this CAPTCHA is not a good and kind man. Try to find difference between O and 0 in this CAPTCHA. If this is an anti-OCR protection, it's also anti-user protection too :)
themail.com
Found at: http://themail.emailonyoursite.com/signup/
Well, position is not permanent, but bad color management make all noise just funny.
nnm.ru
Found at: http://www.nnm.ru/registration.html
Nice CAPTCHA with several weak places: arithmetic operations are not realy an obstacle. Bad noise, easy to remove. Same font, same size, same position. It helps a lot :)
mail.netman.ru
Found at: http://mail.netman.ru/register/?agree=yes
At least CAPTCHA which made with thinking about how it may be beated. Weakness: bad color model, no noise, several fonts, several sizes.
Liveinternet.ru
Found at: http://www.liveinternet.ru/journal_register.php
Well, a little bit harder. But the noise is easy to remove, then we have the same situation - same font, size, position...
freehosting.myplace.com
Found at: http://freehosting.myplace.com/
Still wery weak CAPTCHA - same font, same size, same position.
- F.A.Q.
Q: What does this list include?
A: This is the list of CAPTCHAs we found, which are easy to break, and we are either already broke it or we are absolutely sure we can do this.Q: What do you mean telling "broke"?
A: This mean that we have working application which takes image and outputs the text written on it with accuracy which allows to make automation process reasonable (or we sure we can do this).Q: Can you check CAPTCHA on my site and tell me it it's secure enough?
A: Yes, we can. Contact us.