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Analyzing CAPTCHAs

Posted by CmdrTaco on from the i-fail-more-than-i-win dept.

Bruce Schneier's blog pointed me to a research paper on "Attacks and Design of Image Recognition CAPTCHAs" (PDF). The abstract says, "We systematically study the design of image recognition CAPTCHAs (IRCs) in this paper. We first review and examine all IRCs schemes known to us and evaluate each scheme against the practical requirements in CAPTCHA applications, particularly in large-scale real-life applications such as Gmail and Hotmail."

4 of 105 comments (clear)

  1. Chinese CAPTCHA farms by Anonymous Coward · · Score: 2, Informative

    I have a friend that used to bot WoW for a couple years until Blizzard got the law on their side^H^H^H^H^H^H^H^H^H^H^H^H^H in their pocket. Turns out he used to redirect bot checking CAPTCHAs to an IRC channel where the paid minions would solve them.

    CAPTCHA has been a moot point to me since I witnessed this process occur in real time.

    1. Re:Chinese CAPTCHA farms by buck-yar · · Score: 3, Informative

      I heard porn sites were require a captcha to view an image, but it was really a redirect from another captcha. So porn surfers were solving captchas for bots.

  2. Re:hmm... by SirKveldulv · · Score: 2, Informative

    Yes you can. Costs From $2-7/1000.

  3. I dread Craptcha by GarryFre · · Score: 2, Informative

    Have you ever ran into Captcha that claims your response is wrong when its obvious that is is NOT wrong and tried the audio stuff? The audio version is so retarded its disgusting. It usually features two guys with grossly distorted voices uttering what sounds like 14 words of gibberish in some short conversation at the breakneck speed of an auctioneer or bugs bunny on Helium. Not a single word can be understood, and then it asks for the two words in the sentences. The worst I had ever seen of this kind of foolishness was Dev Shack. It sounds like a great site for programming resources but I can never join because I can't get past their defective Captcha. I can't even tell them its broken because the Captcha prevents any such messages from getting through. This is what I call "Craptcha" and this is no Fraudian slop. I used to run into a few like this, but not lately, but when I do, I still get that sick sinking feeling.

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