How does the “I’m not a robot” checkbox work? – Medium
Asking you to click a checkbox to confirm that you are, in fact, human seems curiously today’s age, there’s a high chance that you, dear reader, are a machine. Maliciously-programmed internet bots (software applications that can run automated tasks) are an unfortunate commonplace on the internet. They can be used at various scales from generating fake social media accounts, to rapidly booking out all tickets for a popular concert and orchestrating a large-scale Distributed Denial of Service (DDoS) attack; a DDoS is an attempt to make an online service unavailable by overwhelming it with traffic. It’s the type of high-profile attack that can take down everything from banks to government websites. A dystopian world like this needs a reliable way to differentiate an evil bot from a well-intentioned human. How can a banking website be sure that an innocent grandma who is logging in to check that the holiday gift money was successfully transferred to her grandchildren, is in fact, an innocent grandma? Enter, the “Completely Automated Public Turing test to tell Computers and Humans Apart”, or more simply, the like internet bots themselves, and like much of the innovation on the internet, CAPTCHAs find their origin in the hacker community. Back in the ancient 1980s the hackers invented leetspeek to bypass security filtering on internet chat forums. Leet is a method of converting words to lookalike characters or abbreviations that cannot easily be interpreted by a computer:leet > I33tcensored > c3n50redporn (pornography) > pr0nIn the pre-Google days of the internet, websites would be manually submitted to search engines. In order to prevent the submission of fake websites, AltaVista implemented the first CAPTCHA-like system that required a user to type a series of distorted characters into a box. This approach, which we often still encounter when registering new accounts or submitting information on the internet, is based on three principles:Humans can more easily recognise highly distorted, rotated or skewed can more easily visually separate overlapped can more easily draw on context to understand visually distorted characters, for example, identifying a character based on the full word that it appears search engine Alta Vista was one of the first popular websites that introduced a CAPTCHA-like protection when submitting new websites to its 2003, a research team from Carnegie Mellon University published a pioneering research paper that described many different types of software programs that could distinguish humans from computers. It was this group that also coined the catchy acronym. As CAPTCHAs became a status quo of security on the Internet, Luis von Ahn, a member of the original research team, became increasingly uncomfortable with how much valuable time was being wasted on solving these mini puzzles. In a wonderful 2011 TED Talk, von Ahn estimated that humanity as a whole was wasting 500, 000 hours a day on completing Von Ahn discusses how the collective amount of time wasted on filling out CAPTCHAs inspired the reCAPTCHA ioning whether this time could be put to more powerful and meaningful use, he developed reCAPTCHA, which was eventually sold to Google in 2009. These days, there are a number of projects and companies (including Google Books, the Internet Archive, Amazon Kindle and The New York Times) that are scanning and indexing large numbers of books, documents and images for use on the web. reCAPTCHA works by taking any of the scanned words that cannot be recognised and presenting them to a human alongside a known word for interpretation. By typing the known word correctly, you identify yourself as a human and the reCAPTCHA system gains some confidence that you have correctly digitised the second. If 10 other people agree on the transcription of the unknown word, the system will assume this to be correct. Today reCAPTCHA helps to digitise millions of books a year and has also extended to support other efforts like digitising street names and numbers on Google Maps or recognising common objects in photos for Google original reCAPTCHA asks you to type a known scanned word to identify yourself as a human and to help transcribe another word that a computer was not able to forms of CAPTCHAs are also being used to help index images and data captured by Google Street are many other forms of CAPTCHAs, including an audio version for the visually impaired. But it is the curiously simple variety — the “I’m not a robot” checkbox seen on many of today’s websites — that inspired the original question behind this article. This checkbox, endearingly called the “no CAPTCHA reCAPTCHA”, is a Google product that unsurprisingly uses a combination of advanced Google technology to produce a very simple result. Google will analyse your behaviour before, during and after clicking the checkbox to determine whether you appear human. This analysis might include everything from your browsing history (malicious bots don’t necessarily watch a few YouTube videos and check their Gmail before signing up for a bank account), to the way you organically move your mouse on the page. If Google is still unsure of your humanness after clicking the checkbox, you will be shown a visual reCAPTCHA (with words, street signs or images) as an additional security measure. This multi-faceted approach is necessary as computers become more skilled at complex image recognition and with the rise of CAPTCHA sweatshopping (think a large room of underpaid workers tasked with generating a heap of fake social media accounts).
How does Google reCAPTCHA v2 work behind the scenes?
This post refers to Google ReCaptcha v2 (not the latest version)
Recently Google introduced a simplified “captcha” verification system (video) that enables users to pass the “captcha” just by clicking on it.
But how can it differentiate a bot from a person just by a click?
As per this answer, (assuming a similar implementation), at first “recaptcha” generates a hidden key and attaches it to a hidden input element and also lazily renders a check box (not an actual check box input but a div) with the same key which when clicked, sends an asynchronous request (XHR) to the Google backend servers to mark it as a valid verification key (i. e. a key that has to be validated when the form is submitted).
But why can’t bots automate that click (at least, browser-based bots)?
How might this work?
asked Dec 4 ’14 at 4:19
8
This is speculation, but based on Google’s reference to the “risk analysis engine” they use ()
I would assume it looks at how you behaved prior to clicking, how your cursor moved on its way to the check (organic path/acceleration), which part of the checkbox was clicked (random places, or dead on center every time), browser fingerprint, Google cookies & contents, click location history tied to your fingerprint or account if it detects one etc.
It’s fairly difficult to fake “organic” behavior in such a way that it would fool a continuously learning pattern detection engine. In the cases where it’s not sure, it still prompts you to match an actual CAPTCHA string.
answered Dec 4 ’14 at 16:50
AgmLauncherAgmLauncher6, 5945 gold badges38 silver badges63 bronze badges
18
A new paper has been released with several tests against reCAPTCHA:
Some highlights:
By keeping a cookie active for +9 days (by browsing sites with Google resources), you can then pass reCAPTCHA by only clicking the checkbox;
There are no restrictions based on requests per IP;
The browser’s user agent must be real, and Google run tests against your environment to ensure it matches the user agent;
Google tests if the browser can render a Canvas;
Screen resolution and mouse events don’t affect the results;
Google has already fixed the cookie vulnerability and is probably restricting some behaviors based on IPs.
Another interesting finding is that Google runs a VM in JavaScript that obfuscates much of reCAPTCHA code and behavior. This VM is known as botguard and is used to protect other services besides reCAPTCHA:
UPDATE 2017
A recent paper (from August) was published on WOOT 2017 achieving 85% accuracy in solving noCAPTCHA reCAPTCHA audio challenges:
UPDATE 2018
Google is introducing reCAPTCHA v3, which looks like a “human score prediction engine” that is calibrated per website. It can be installed into different pages of a website (working like a Google Analytics script) to help reCAPTCHA and the website owner to understand the behaviour of humans vs. bots before filling a reCAPTCHA.
answered May 10 ’16 at 19:13
barbolobarbolo3, 5871 gold badge28 silver badges30 bronze badges
3
My Bots are running well against ReCaptcha.
Here my Solution.
Let your Bot do this Steps:
First write a Human Mouse Move Function to move your Mouse like a B-Spline (Ask me for Source Code). This is the most important Point.
Also use for better results a VPN like
For every Recpatcha do these Steps:
If you use VPN switch IP first
Clear all Browser Cookies
Clear all Browser Cache
Set one of these Useragents by Random:
a. Mozilla/5. 0 (compatible; MSIE 9. 0; Windows NT 6. 1; Trident/5. 0)
b. 0 (Windows NT 6. 1; WOW64; rv:44. 0) Gecko/20100101 Firefox/44. 0
5 Move your Mouse with the Human Mouse Move Funktion from a RandomPoint into the I am not a Robot Image every time with different 10×10 Randomrange
Then Click ever with random delay between
WM_LBUTTONDOWN
and
WM_LBUTTONUP
Take Screenshot from Image Captcha
Send Screenshot to
or
and let they solve.
After receiving click cooridinates from captcha solver use your Human Mouse move Funktion to move and Click Recaptcha Images
Use your Human Mouse Move Funktion to move and Click to the Recaptcha Verify Button
In 75% all trys Recaptcha will solved
Chears Google
Tom
answered May 13 ’16 at 22:21
IngoIngo4, 9521 gold badge26 silver badges23 bronze badges
May I present my guess, since this is not a open technology.
Google says it’s about combing information from before, during, after to distinguish human from robot. But I am more interested about that final click on the check box.
Say, the POST data (solved CAPTCHA) has a field called fingerprint, a string calculated from user behavior. I think there may be a field about that check box location. I guess this check box is in a coordinate system randomly generated by Google back-end and encrypted by the public key of my site. So, a robot may “guess/calculate” a location about this box, but when site owner makes the GET query with private key to verify user identity, Google will decrypt the coordinate system and say if the user click on the right place. So, only one possible right click(with some offsets, it’s a square box) location in this random coordinate system owned by only Google and site owners.
4ae1e16, 4187 gold badges40 silver badges72 bronze badges
answered Jan 3 ’15 at 4:26
hakunamihakunami2, 1444 gold badges26 silver badges46 bronze badges
Please remember that Google also use reCaptcha together with
Canvas fingerprinting
to uniquely recognize User/Browsers without cookies!
answered Oct 28 ’19 at 13:28
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CAPTCHA: Hard for Humans, Easy for Bots – PerimeterX
CAPTCHA: A Well-worn Approach to Bot Defense
For years, website owners have used a number of approaches and technologies to battle constantly evolving bot threats. One of the most common ways to battle bots has been to use CAPTCHAs, a challenge-response mechanism that promised an easy way to distinguish between a bot and a human. CAPTCHA is an acronym for completely automated public Turing test to tell computers and humans apart. Used in millions of sites, CAPTCHA is employed to help prevent bots from doing form submissions, executing logins and accessing sensitive pages or processes.
How CAPTCHA Has Evolved
As bot-based threats have evolved, so have the CAPTCHA mechanisms intended to stop them. In its early forms, users were asked to read distorted text and submit it in a form.
An example of one of the types of Google reCAPTCHAs that are most commonly used today.
Today, Google reCAPTCHA represents the dominant form of CAPTCHA technology in use. One study found that, across one million of the world’s top websites that employ CAPTCHA, Google reCAPTCHA was deployed by 94% of them.
How CAPTCHA Is Failing
In spite of its widespread, continued usage, there are two very fundamental problems with CAPTCHA:
User experience: From a user standpoint, as just about anyone alive can tell you, the experience is a poor one. It’s time-consuming, increasingly difficult, and can often keep legitimate users from doing what they want and need to do.
Efficacy: From a security standpoint, quite simply, it doesn’t work. The challenge is supposed to be easy for users, and hard for bots, but in fact, it’s become quite the opposite.
Following is an overview of the plethora of options available that make it easy to bypass CAPTCHA challenges.
How Attackers are Easily Bypassing CAPTCHA Challenges
There are a number of CAPTCHA-solving technologies and services available to attackers today. Attackers choose the solvers that work best against the type of CAPTCHA used on a target site. Here are two high-level categories:
Automated Technologies and Plug-ins
There is a range of automated technologies, including APIs, browser plug-ins and extensions that enable attackers to bypass or solve CAPTCHA challenges. Here are a few examples:
A group of researchers from Lancaster University, Northwest University and Peking University used the concept of a generative adversarial network (GAN) in order to create an extremely fast and accurate CAPTCHA solver.
There are several free online CAPTCHA solving services and libraries that leverage deep learning-based technologies, including GRIS, Alchemy, Clarifai and NeuralTalk. Academic studies show that deep-learning-based approaches are highly accurate in solving CAPTCHA challenges.
DeCaptcher is an example of one of the solving services available via APIs making it easy to integrate into applications. Based on an optical character recognition system, the service solves challenges and provides a file to download that details the time, the challenge image, and the text used to solve the challenges.
Open-source tools and browser extensions, including Buster and UnCaptcha, use audio recognition that was intended to help visually impaired users and abuses it to bypass CAPTCHA mechanisms in an automated fashion.
Human-assisted Solving Services
In addition, there are also human-powered services that are available. These services are often staffed by people who work in so-called farms. These services are easy to find via a simple Google search. These services make it cost-effective for attackers to bypass the object recognition challenges used in reCAPTCHA.
2captcha and anti-captcha are some of the most popular examples of such a service. At a high level, these services enable customers to submit target websites, often via an API, to the vendor. The vendor’s staff will solve the challenge and provide the solution back to the customer. These vendors advertise solving 1, 000 regular CAPTCHA challenges for as little as $1. 00, and 1, 000 reCAPTCHA challenges for between $1. 99 and $2. 99.
Increasing Prevalence and Usage of CAPTCHA Solvers
Given their low/no cost, availability and efficacy, the use of CAPTCHA solvers continues to grow. With our PerimeterX Bot Defender solution, we’ve detected a rapid expansion in the use of CAPTCHA solvers. As the diagram below illustrates, between August 2019 and March 2020, we saw a significant increase in the volume of attempted attacks that employed CAPTCHA solvers.
Given their accessibility and ease, the use of CAPTCHA solvers has grown rapidly.
Conclusion
It’s abundantly clear that users and businesses can’t stand CAPTCHA mechanisms that interrupt the user flow and ultimately lower conversions on websites. Particularly as artificial intelligence continues to improve, standalone visual-challenge-response approaches aren’t viable. Quite simply, organizations can’t rely solely on CAPTCHA-based mechanisms to combat bots, given the abundance of CAPTCHA solvers. These realities are exposing a very clear demand for advanced mechanisms that don’t frustrate users and are difficult for bots to solve.
Frequently Asked Questions about how does the new recaptcha work
How does Google captcha work?
and let they solve.After receiving click cooridinates from captcha solver use your Human Mouse move Funktion to move and Click Recaptcha Images.Use your Human Mouse Move Funktion to move and Click to the Recaptcha Verify Button.May 11, 2016
Does reCAPTCHA really work?
Efficacy: From a security standpoint, quite simply, it doesn’t work. The challenge is supposed to be easy for users, and hard for bots, but in fact, it’s become quite the opposite.Mar 26, 2020
How does Protected by reCAPTCHA work?
reCAPTCHA protects your website from fraud and abuse without creating friction. reCAPTCHA uses an advanced risk analysis engine and adaptive challenges to keep malicious software from engaging in abusive activities on your website.