shackspace hacker samuirai is always on the prowl for something to break^W fix.

The latest thing he fixed is the minteye CAPTCHA system.  The CAPTCHA works by having the user move a slider left and right which directy affects a distorted image.  There’s one setting of the slider where the image is no longer distorted which is the correct solution to the CAPTCHA.

This works quite well if you can see but not if you’re blind.  To ensure accessibility there’s also a voice output feature which comes with three handy messages allowing you to solve the test and identify yourself as a human: 1) move slider to the left, 2) move slider to the right, 3) slider is in correct position.

The thing that was missing (and is now fixed) was an easy way to do this annoying task automatically so your friendly computer can login in your stead ;)

To solve this samuirai didn’t actually attack the system via the images it displays but instead used Google’s speech2text API to have the messages for blind users translated into text which can then easily be evaluated automatically by a script that tries to find the right position for the slider iteratively.

He’s got a write-up of his hack available online on Github and there’s also a short YouTube video showing the automatic CAPTCHA solver script doing its magic.

 

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Urspünglich gepostet: Januar 13th, 2013
Tags: Allgemein

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