A CAPTCHA bot is a computer program that automatically fills in the CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) with the answer it has been programmed to guess.
How does it work?
A CAPTCHA bot program works by utilizing a brute force method to guess the answer to a CAPTCHA. This involves running through all possible answers until one of them is correct, and then continuing with the next question. Therefore, this type of cyberattack can take an extensive amount of time and resources to complete. Because of this, CAPTCHA bots are typically used in conjunction with other types of cyberattacks such as phishing campaigns or malware distribution to increase their likelihood of success.
Why are they used?
CAPTCHA bots are generally used for two purposes:
- To gain access to systems without permission. CAPTCHA bots are used to get unauthorized access to systems by repeatedly filling out forms with guessed answers, or sending requests with proper authorization credentials to be approved multiple times over. This type of cyberattack can result in massive distributed denial-of-service (DDoS) attacks on websites that require users to sign up or log in to an account before using their services.
- To circumvent the security of a system. CAPTCHA bots are utilized when cybercriminals attempt to commit fraud by defeating the security measures put in place by banks, credit card companies, and other financial institutions. This type of cyberattack often takes the form of phishing campaigns or malware distribution, which can include cryptojacking scripts that mine cryptocurrency on an affected device without permission.
How to protect yourself against CAPTCHA bots?
To protect yourself against these types of attacks you should follow some best security practices:
- Only use secure websites for banking or purchasing online services.
- Look at the address bar of your browser before entering any personal information through a website.
- Update your software regularly.
- Never click on links in emails claiming to offer refunds for errors made by their company.
- Use multi-factor authentication whenever possible (e.g., text messages, authenticator apps, security keys).