How can CAPTCHAs be cracked?

I heard recently that gmail's and window's live captchas already have been compromised by spam bots. That's some feat of cracking engineering, how in the hell did they manage to crack these?

http://www.websense.com/securitylabs/blo...

has a detailed write up of how they did it against google. As far as I can follow, the image is chopped up and distributed to many places for analysis. A study shows that computers are very good at single character recognition, even if those characters are skewed. So if you can divide up an image and process each letter, you can solve the captcha. (20% of the time)

yes, there are also shops in all over the world that pay people pennies to sit all day and decipher the captchas.

I think they have CAPTCHA sweatshops in China.

Thats amazing! Who knows maybe it read the screen by location! Haha no doubt the worlds security will be beaten by programs.

We still have to wait for an answer, given that they cannot figure it out either as mentioned on http://www.theregister.co.uk/2008/02/08/...

It's something sophisticated enough that manages to bypass the captcha about 1/3 of the times - I would say it's doing OCR but I doubt it's that simple.

A number of ways...one of the more creative ways I have seen was to pipe them into an application, and the user actually enters them in....why? Well, because the hot blondie on the screen takes off another article of clothing for each captcha that is entered...

There are some more sophisticated ways out there...but when they are cracked, they are shared amongst the malware community...

I've seen "job postings" similar to what the other user mentioned. The captchas are piped into an application and they are entered by people. I saw an ad for "Enter a simple code over and over, I will pay $5 per 5000 entered."

Sounds like this time it might be something else though.

Since that is a social device the cracking is also social. They piped the images of CAPTCHA to a harmless striptease site and trick others to read it for them.