I, Me & Technology

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Tag Archives: Captcha

How CAPTCHA works

Simplest link to start: link

Dictionary attacks

These are kind of attacks where computer scripts attempt to login by using randomly generated strings, retrieved from dictionary, as passwords

How to use recaptcha:

1. Open up a URL:


This URL dumps a javascript like below on the browser:

var RecaptchaState = {
site : ‘6LcCg8wSAAAAANPY_SYuAMe7l_dObfxYaukMvFhy’,
rtl : false,
challenge : ’03AHJ_VustfccfCb4QLjCJMe6uC37xVFQZzDjwKloijcCHTlaXWbpZ5-5Q6I-B3iGP7dE-Ob4JSWexiU2RHGq2bHOtkVNTuH2mFl6cC4Zvjf8NLdZpgHzBrP0l_0KmvQNrsNb_ZTtqEgYwISoR3Qg5DJIaKK0XKnrkE7ocy-3cbP4Lr8M3vLKJzmw’,
is_incorrect : false,
programming_error : ”,
error_message : ”,
server : ‘https://www.google.com/recaptcha/api/’,
lang : ‘en’,
timeout : 1800


2. Look out for challenge field: Use the value in the challenge field with https://www.google.com/recaptcha/api/image?c=

U can get new captchas on every refresh of second url