Online scams have existed since the dawn of the Internet, with attackers trying various methods to bypass security mechanisms. One of the oldest and most effective security methods to stop online scams has been CAPTCHA or Completely Automated Public Turing Test to tell Computers and Humans Apart. CAPTCHA has served as a control to differentiate if the requester accessing a website or platform is a human being or an automated bot,  and helps ensure that only legitimate human users can access these systems and carry out activities. CAPTCHA has been a powerful tool against automated attacks for many years. However, cybercriminals are evolving their tactics to bypass even this tried and tested control. In this article we go over how CAPTCHA scams, how these controls can be circumvented and what these new tactics mean for the security of online systems. 

Why is CAPTCHA needed?

Cybercriminals have often used bots to automate malicious activities such as data scraping, brute forcing, spamming, etc. CAPTCHA has served to deter such actions by providing a challenge that requires human intelligence to solve. This can be a puzzle, distorted image, text, or audio. The point is to make it difficult for bots to understand and bypass this challenge, and CAPTCHA is commonly found in login pages, comment sections, and other interactive areas where a bot is at risk of gaining access and spamming legitimate users.  CAPTCHA has proved to be an effective security control for many years now due to its requirement for a human-dependent task to be carried out. 

CAPTCHA’s challenges are typically too complex for bots to interpret, stopping them in their tracks. However, cybercriminal’s motivation for compromising CAPTCHA has remained high as it can allow them to mass create fake accounts, spam emails, plant malicious links and even launch Denial of Service attacks without any restrictions. Hence cybercriminals have been continually improving the sophistication and effectiveness of their attacks with CAPTCHA scams bypassing these controls becoming a growing menace. 

CAPTCHA Challenges

As attacks increase in intelligence, CAPTCHA now faces the following challenges: 

• Bots have become more sophisticated and intelligent over the years and can now solve simple CAPTCHA challenges by analyzing them. Cybercriminals have employed advanced techniques to reverse engineer CAPTCHA algorithms enabling them to identify patterns and trends within the code that can be exploited. This allows them to develop bots that use these vulnerabilities and bypass CAPTCHA controls.  
• The rise of AI is another risk, as bots powered by machine learning can analyze pictures and complex text meant for humans and interpret it, allowing them to bypass CAPTCHA protection. These bots are trained on massive datasets with CAPTCHA images and their answers, allowing them to solve these challenges quickly.  
• Human agents are present who are willing to solve CAPTCHA challenges for a small fee. These services are available for cybercriminals to take advantage of, saving them time and resources. These agents are typically present in third-world countries allowing attackers to take advantage of cheap labor.

If CAPTCHA scams are able to bypass this security control, it can have severe implications for the security of online systems. Attackers could gain access to sensitive functions within a system, allowing them to scrape data, spread malware and spam users without any restrictions. CAPTCHA is a ubiquitous control used by thousands of companies worldwide, and bypassing its security features can become a risk to millions of users across the globe. 

How to protect against the new wave of attacks

To counter this new wave of advanced attackers, cybersecurity teams need to invest and implement more advanced CAPTCHA solutions capable of detecting and protecting against their techniques. Instead of simple image or audio challenges, more complex human-intuitive challenges can be introduced, like games that are easy for human beings to understand but difficult for bots. 

CAPTCHA can also be augmented with AI-based controls that analyze behavioral risk of users who attempt to answer its challenges. By analyzing multiple context-based factors such as keystrokes, location, browsing patterns, etc. CAPTCHA can infer if the requester is a human or a bot. This  can be effective against humans who are simply there to solve CAPTCHA challenges with malicious intentions. 

Conclusion

As a control, CAPTCHA needs to evolve with the times to stay relevant. It is clear that modern attacks have become too sophisticated for standard CAPTCHA controls, and a rethink is needed. New and more innovative styles of challenges need to be implemented within these security controls, along with the ability to detect if the user is a bot or a human. This will help apply multiple layers of security that can stop even the most intelligent bot in its tracks. Using contextual-based rules powered by AI and machine learning, CAPTCHA can even identify human agents who only try to bypass it with malicious intentions. 

Cybersecurity is an ongoing cat-and-mouse game between cybercriminals and security teams. As attacks become increasingly sophisticated, the answer is not to shelve security controls like CAPTCHA but to evolve them and harden them against modern-day attacks. Provided we mature and improve this control, CAPTCHA scams will not succeed and this control has a long future ahead in the world of cybersecurity.

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