Hard Captcha
Why captchas are getting harder – Vox
It’s not you — captchas really are getting harder. The worst thing is that you’re partly to blame.
A captcha is a simple test that intends to distinguish between humans and computers. While the test itself is simple, there’s a lot happening behind the scenes. The answers we give captchas end up being used to make AI smarter, thus ratcheting up the difficulty of future captcha tests.
Is there any feeling more frustrating than clicking all the correct answers and getting a “please try again”?
Screenshot, Edward Vega
But captchas can be broken by hackers. The tests we’re most familiar with have already been broken. Captcha makers try to stay ahead of the curve but have to balance increasing the difficulty of the test with making sure any person — regardless of age, education, language, etc. — can still pass it. And eventually, they might have to phase out the test almost entirely.
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Correction, May 19: At 5:22 in the video, there is an incorrect statement on Google’s use of reCaptcha V2 data. While Google have used V2 tests to help improve Google Maps, according to an email from Waymo (Google’s self-driving car project), the company isn’t using this image data to train their autonomous cars. For more on the future of self-driving cars, check out this article from Vox’s Kelsey Piper.
How to bypass CAPTCHAs easily using Python and other methods
Internet service providers generally face the risk of authentication-related attacks, spam, Denial-of-Service attacks, and data mining bots. Completely Automated Public Turing test, to tell Computers and Humans apart, popularly known as CAPTCHA, is a challenge-response test created to selectively restrict access to computer systems. As a type of Human Interaction Proof, or a human authentication mechanism, CAPTCHA generates challenges to identify users. In essence, a CAPTCHA test can tell machines/ computers and humans apart. This has caused a heightened adoption of CAPTCHAs across various online businesses and services.
The concept of CAPTCHA depends on human sensory and cognitive skills. These skills enable humans to read a distorted text image or choose specific images from several different images. Generally, computers and computer programs such as bots are not capable of interpreting a CAPTCHA as they generate distorted images with text or numbers, which most Optical Character Recognition (OCR) technologies fail to make sense of. However, with the help of Artificial Intelligence, algorithms are getting smarter and bots are now capable of cracking these tests. For instance, there are bots that are capable of solving a text CAPTCHA through letter segmentation mechanisms. That said, there aren’t a lot of automated CAPTCHA solving algorithms available.
This article outlines the various methods of generating and verifying CAPTCHAs, their application, and multiple ways to bypass CAPTCHAs.
Reasons for using CAPTCHA
Web developers deploy CAPTCHAs on websites to ensure that they are protected against bots. CAPTCHAs are generally used to prevent:
Bots from registering for services such as free email.
Scraper bots from gathering your credentials or personal information, upon logging in or while making online payments.
Bots from submitting online responses.
Brute-force bot attacks.
Search engine bots from indexing pages with personal/ sensitive information.
General flow of CAPTCHA generation and verification
The image below represents the common method of generating and verifying CAPTCHAs:
Application of different types of CAPTCHA and how to bypass them
I. reCAPTCHA and the protection of websites
Google reCAPTCHA is a free service offered to prevent spam and abuse of websites. It uses advanced risk analysis techniques and allows only valid users to proceed.
Process flow diagram of Google reCAPTCHA
How to bypass reCAPTCHA?
Verification using browser extensions
Browser extensions such as Buster help solve CAPTCHA verification challenges. Buster, for instance, uses speech recognition software to bypass reCAPTCHA audio challenges. reCAPTCHA allows users to download audio files. Once it is downloaded, Google’s own Speech Recognition API can be used to solve the audio challenge.
CAPTCHA solving services
Online CAPTCHA solving services offer human based services. Such services involve actual human beings hired to solve CAPTCHAs.
II. Real person CAPTCHA and automated form submissions
The jQuery real person CAPTCHA plugin prevents automated form submissions by bots. These plugins offer text-based CAPTCHAs in a dotted font. This solves the problem of fake form submissions.
How to bypass real person CAPTCHA?
The following steps can be used to solve real person CAPTCHAs:
A. Create data set
In this one-time process:
Collect texts from real person HTML tags
Group the texts based on the words
Create data set model for A-Z words (training data)
B. Testing to predict the solutions
After successfully completing process A, set up a process to:
Fetch the word from the data set model created in process A.
Example:
from selenium import webdriver
import time
dataset = {‘ * * * * * ******* ‘: ‘J’,
‘******* * * * * * *’: ‘L’,
‘******** * ** * ** * ** * ** * * ** ** ‘: ‘B’,
‘* * * **** * * * ‘: ‘Y’,
‘* * * ******** * * ‘: ‘T’,
‘ ***** * ** ** ** ** * * * ‘: ‘C’,
‘******** * ** * ** * ** ** ** *’: ‘E’,
‘******** ** ** ** ** * ***** ‘: ‘D’,
‘* ** ** ********* ** ** *’: ‘I’,
‘ ***** * ** ** ** ** * ***** ‘: ‘O’,
‘******* * * * * * *******’: ‘M’,
‘******* * * * * * *******’: ‘N’,
‘******** * * * * * * * * ‘: ‘F’,
‘ ** * * * ** * ** * ** * ** * * * ** ‘: ‘S’,
‘ ***** * ** ** ** * ** * **** *’: ‘Q’,
‘******* * * * * * * * * * * *’: ‘K’,
‘ ** ** ** * * * ** * ** **’: ‘A’,
‘****** * * * * ******* ‘: ‘U’,
‘******* * * * * * *******’: ‘H’,
‘** ** ** * ** ** ** ‘: ‘V’,
‘* ** *** * ** * ** * *** ** *’: ‘Z’,
‘******** * * * * * * * * * ** ‘: ‘P’,
‘* * * * * * * * * * * * *’: ‘X’,
‘ ***** * ** ** ** * ** * * * ** ‘: ‘G’,
‘******** * * * * * * ** * * * ** *’: ‘R’,
‘******* * * * * * *******’: ‘W’}
def group_captcha_string(word_pos):
captcha_string = ”
for i in range(len(word_pos[0])):
temp_list = []
temp_string = ”
for j in range(len(word_pos)):
val = word_pos[j][i]
temp_string += val
if ():
(val)
if temp_list:
captcha_string += temp_string
else:
captcha_string += ‘sp’
return (“spsp”)
# create client
client = ()
(“)
(3)
# indexing text
_get = lambda _in: {index: val for index, val in enumerate(_in)}
# get text from html tag
captcha = nd_element_by_css_selector(‘form [class=”realperson-text”]’)(‘\n’)
word_pos = list(map(_get, captcha))
# group text
text = group_captcha_string(word_pos)
# get text(test)
captcha_text = ”(list(map(lambda x: dataset[x] if x else ”, text)))
print(“captcha:”, captcha_text)
III. Text-in-image CAPTCHA
Text-based/ text-in-image CAPTCHAs are the most commonly deployed kind and they use distorted text rendered in an image. There are two types of text-based CAPTCHAs:
Simple CAPTCHA
Simple CAPTCHAs can be bypassed using the Optical Character Recognition (OCR) technology that recognizes the text inside images, such as scanned documents and photographs. This technology converts images containing written text into machine-readable text data.
import pytesseract
import sys
import argparse
try:
import Image
except ImportError:
from PIL import Image
from subprocess import check_output
def resolve(path):
print(“Resampling the Image”)
check_output([‘convert’, path, ‘-resample’, ‘600’, path])
return age_to_string((path))
if __name__==”__main__”:
argparser = gumentParser()
d_argument(‘path’, help = ‘Captcha file path’)
args = rse_args()
path =
print(‘Resolving Captcha’)
captcha_text = resolve(path)
print(‘Extracted Text’, captcha_text)
# command to run script
python3
Complicated CAPTCHA
These text-in-image CAPTCHAs are too complex to be solved using the OCR technology. Instead the following measures can be considered:
Build machine learning models such as Convolutional Neural Network (CNN) or Recurrent Neural Network (RNN)
Resort to CAPTCHA solving services
IV. Sum of integers or logical operations
This unique challenge involves solving mathematical problems, particularly, finding the sum of integers.
To bypass this challenge, one can:
Extract text from HTML tags or images
Identify the operator
Perform the logic
Get the result
V. Mitigating DDoS attacks using CAPTCHAs
In distributed denial-of-service attacks, cyber criminals target network resources and render them inaccessible to users. These attacks temporarily or indefinitely slows down the target resource by flooding the target with incoming traffic from several hosts. To prevent such attacks, businesses use CAPTCHAs.
The following methods or programs can be used to bypass DDoS protected sites:
JavaScript supported browsers (Chrome/ Firefox)
Deriving logic to generate DDoS answers
Fetch the DDoS problem on the site and execute it using
Senior Software Engineer
He is a Senior Software Engineer working as a part of the Data Acquisition team at CloudSEK. In his role, he is responsible for writing reusable codes and scalable web crawlers for XVigil. In his spare time, Sellamani loves to take on new challenges and find solutions to real-time problems.
Cyber Intelligence Editor,
CloudSEK
Total Posts: 2
She is a Cyber Intelligence Editor at CloudSEK. A lawyer by training and a content writer by choice, she prefers to write on matters concerning current affairs, security, and human frailty.
What to Do When CAPTCHAs Won’t Work – LiveAbout
How to Deal With Invalid CAPTCHA Codes
CAPTCHAs are distorted letters and numbers that aim to block bots and scripts from submitting forms online. This is a benefit for real people who want to enter sweepstakes, because it helps prevent cheaters from entering.
However, bots become more adept at deciphering CAPTCHAs over time, which means programmers have to make CAPTCHAs increasingly difficult to read. And that can make entering a form frustrating for real humans as well.
Luckily, there are some strategies that can help. Try these tips if you can’t get a CAPTCHA code to work.
If at First You Don’t Succeed, Load, Load Again
Frustrated by CAPTCHAs? Here Are Some Strategies to Try.
Hero Images/Getty Images
If your CAPTCHA isn’t being accepted, the problem might not be with your reading or your typing, the code may simply have expired. If you didn’t submit your entry form right away, your CAPTCHA might be invalid.
For example, a strategy to enter sweepstakes faster is to open several entry forms at the same time, fill them out, and submit them one after another. But when you do this, it can take a while to actually fill out the entry form.
Many CAPTCHAs have an anti-hacking feature that causes them to expire after a few minutes. This prevents hackers from, say, sending the CAPTCHA image to a CAPTCHA mill service, where low-wage workers crack the code and send it back to a hacker.
To see if this is the problem, try reloading the page to get a new code, then fill out and submit the form right away.
Llamas, Iguanas, and the Number 1
Depending on the font a CAPTCHA uses, a lower-case “l” as in “llama” can look exactly the same as an uppercase “I” as in “Iguana”, or even the number “1. ” Confusion between these three characters could be the reason why you can’t get the CAPTCHA to work properly.
If your CAPTCHA won’t submit, check for these symbols. If it contains one of them, try the other possibilities.
O, Those Zeros
It can be very difficult to tell the difference between an uppercase letter “O” as in “Ocean” and the numeral “0” or zero. This is especially true when the CAPTCHA has distorted the characters.
If you’ve been trying the letter O or the number zero and the CAPTCHA won’t go through, try the other option.
Forget 2, 4 the Problem’s 6 and 8
The numbers “6” and “8” are clearly different, right? Well, they are until CAPTCHAs put squiggly lines behind them to confuse automatic image readers. One of those squiggles could easily make it hard to tell the difference between the two numerals.
Squiggles can confuse many other characters as well. Depending on placement and font, a “c” can look like an “o, ” an “o” look like an “a, ” and other characters can be hard to distinguish.
If your CAPTCHA is being rejected, take a close look to make sure that your eyes aren’t being thrown off by background graphics.
A Case of the Wrong Case
Some CAPTCHAs don’t care if the letters you enter are upper or lowercase, but others are case-sensitive. That means that your shift key might be the reason why your CAPTCHA isn’t going through.
If the CAPTCHA shows both upper and lowercase letters, be sure to enter your characters exactly as displayed. If all of the letters have the same case, you might be able to enter it either way, but if your entry is refused, try typing it exactly as it’s shown.
When Case Sensitivity Is Too Sensitive
Of course, case-sensitive captchas open the door for even more confusing letters. For example, an uppercase “O” can look a lot like a lowercase “o” when letters are different sizes, and the same with “C” and “c. ”
If your CAPTCHA is being stubborn, try changing the case of letters that look the same in upper- and lower-case to see if it helps.
When the Eyes Don’t Have It
One of the drawbacks of CAPTCHAs is that they are difficult for people with visual impairments to use. To get around this problem, some sweepstakes offer an audio version of their captchas.
If this is an option, try listening to a hard-to-enter code. Look for a small speaker symbol near the CAPTCHA to turn on audio mode. It’s often easier to hear the code than to read it.
Use a CAPTCHA Solver
Some companies offer software to solve the problem of difficult CAPTCHAs. If you are getting too frustrated with trying to solve them yourself, try an extension. For some suggestions, check out 4 Extensions to Auto Solve and Bypass CAPTCHA.
There’s No Shame in Admitting Defeat
If you’re still having trouble with a CAPTCHA, you don’t have to let it drive you crazy. Instead, try reloading it to get a different code that might be easier to decipher.
You can usually do this by reloading the page in your browser. Some entry forms also offer the option to click on the code or press a reload button to get an easier-to-read captcha.
Don’t Get Frustrated!
When you enter sweepstakes, annoying CAPTCHAs are just one of the frustrations you might face. Remember, being a winner is a marathon, not a sprint. Be patient and persistent and the prizes will come!
Frequently Asked Questions about hard captcha
Why is CAPTCHA so hard?
While the test itself is simple, there’s a lot happening behind the scenes. The answers we give captchas end up being used to make AI smarter, thus ratcheting up the difficulty of future captcha tests. But captchas can be broken by hackers. The tests we’re most familiar with have already been broken.May 14, 2021
Can I bypass CAPTCHA?
Simple CAPTCHAs can be bypassed using the Optical Character Recognition (OCR) technology that recognizes the text inside images, such as scanned documents and photographs. This technology converts images containing written text into machine-readable text data.
What is bad CAPTCHA?
CAPTCHAs are distorted letters and numbers that aim to block bots and scripts from submitting forms online. … And that can make entering a form frustrating for real humans as well. Luckily, there are some strategies that can help.May 30, 2021
