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CAPTCHA, “Completely Automated Public Turing Test To Tell Computers and Humans Apart”, has been the main method for websites to combat spam, DDoS, and other types of malicious bot attacks for decades.
However, these malicious bots have become much more advanced, and recent developments in machine learning have allowed today’s AIs to consistently and accurately solve Google’s reCAPTCHA.
Meaning, there is a growing concern that CAPTCHAs are simply no longer effective in protecting our websites and networks from bot activities.
This is also made worse by the fact that to make CAPTCHA more effective, we have to make the challenge more difficult. However, the more difficult the test is, the worse user experience it will cause.
The good news is, there are actually various other techniques and methods, like the anti-spam honeypot, that are actually pretty effective in combating today’s malicious bots. Here, we will explore these methods.
CAPTCHA Alternatives That Work
As discussed, the main challenge of using CAPTCHA remains difficult to solve: to combat the increasingly smarter bots and AIs, we have to make the CAPTCHA challenge more complex. However, the harder/longer it is to solve the CAPTCHA the more you’ll disrupt your legitimate users’ activities.
With that being said, many cybersecurity experts have now implemented various other methods to replace CAPTCHA as the anti-bot management method, and here are some of them:
Simple Logical Question
The idea behind a CAPTCHA test is that the test should be as difficult as possible to solve by software (bots), but as easy as possible to solve by human users. Finding the right balance is the challenge.
A good alternative to CAPTCHA is to ask a simple logical (typically mathematical) question that is very easy to solve by humans, but hard to recognize and solve by bots.
For example:
“23-8”, with the numbers obscured so they can’t be recognized by OCR (Optical Character Recognition)
What is the color of Sakura trees in autumn?
The opposite of the south is….
And so on.
While really advanced bots can solve these questions, they can be more effective than regular CAPTCHAs.
Gamified Test
Similar in principle to the above technique, there are CAPTCHA providers that use games to challenge the bots, for example:
Again, they won’t stop the most advanced AIs, but users will be less annoyed compared to normal CAPTCHAs, and they are also more challenging for the bots.
Anti-Spam Honeypot
Honeypot is essentially putting a ‘pot of honey’ (a trap) to lure bots and automated programs so they’ll make mistakes and reveal their identities as bots.
The basic idea is to put something that is going to be detected by a bot (and is ‘attractive’ for its objective) but is hidden from human users. A very basic example is to use words with the same color as the site’s background, but we can also use Javascript or CSS to add a hidden field on the form. Human users won’t be able to see this field, but a bot will scan it.
So, we can filter out any client that clicks this hidden link or any form submissions with this hidden field filled.
There are various different ways we can use to implement the anti-spam honeypot strategy, but the basic principle is to lure the bots with something that is hidden from human users.
Time-Measuring
Another technique that is similar in principle to the anti-spam honeypot is to identify bot activities by measuring the time used by a client to fulfill its action.
Bots are naturally designed to be (much) faster than human users in performing their actions. So, the idea is that by measuring the time required by each client to complete a certain task, we can identify bots from human users.
While bots can deliberately slow down their operation, most bot operators won’t do that since it will mean wasting time and resources. Most bot operators (i.e. hackers) would like to perform the bot’s task as fast as possible, so hopefully, we can discourage them so they’ll simply move on to another target.
Bot Detection and Management Solution
Arguably the most effective and reliable CAPTCHA alternative you can use to detect and manage bot activities is to invest in a dedicated bot management system. This software solution is designed to detect bot activities, differentiate between good bots and bad bots, and manage activities coming from bad bots in real-time.
There are plenty of these solutions available in the market, but it’s very important to choose the right one because:
Today’s very advanced bots are using AI and advanced deep learning technologies to mask their identity as legitimate users. Identifying a bot from legitimate human users can be very challenging, and we wouldn’t want to accidentally block our valuable users.
There are actually good bots that are beneficial for our site (i.e. Googlebot), we also wouldn’t want to accidentally block these good bots that will hurt our site and business’s performance.
It’s best to use a bot management solution that is capable of AI-based, real-time detection like DataDome, which is capable of reliably differentiating between good bots and bad bots; and bots from human users. This way we can prevent false positives and false negatives.
Closing Thoughts
While traditional CAPTCHAs are now considered not very effective in combating today’s really sophisticated bots, there are other solutions besides CAPTCHA that we can use to prevent spam, DDoS, and other bot-related cybersecurity threats.
Anti-spam honeypot is a relatively cost-effective and easy tactic to implement, but arguably if you really wish to protect your network and system from bots, investing in an AI-powered bot detection and management solution that is capable of behavioral-based detection is the most viable CAPTCHA alternative.
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