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CAPTCHAs and how they might affect your scan
CAPTCHAs and how they might affect your scan

Learn more about the CAPTCHA test and its complications towards scanning your target.

Martim Valente avatar
Written by Martim Valente
Updated over a week ago

A CAPTCHA, short for "Completely Automated Public Turing test to tell Computers and Humans Apart," is a challenge-response test used to confirm whether the user is human.

Examples include:

Different types of CAPTCHAs

Different types of CAPTCHAs

The primary goal of a CAPTCHA challenge is to ensure that a human initiates all actions taken on a website. This is typically accomplished through letter and image recognition.

Implementing a CAPTCHA on a website can help protect against bots and spam, and it is highly recommended for use in production.

Helping Probely bypass a CAPTCHA

When using Probely, it's important to allow full access to the target you wish to scan.

The crawler, an automated module that crawls the target and gathers endpoints and injection points for the scanner, cannot solve a CAPTCHA independently.

As a result, a CAPTCHA can block the crawling of a target and hinder the scanning process.

To help Probely bypass a CAPTCHA, you can disable the challenge on a target in a staging environment or allow Probely's outbound IPs to bypass the CAPTCHA in its settings.

If these options do not work, add a cookie that, when presented in a request, will disable the CAPTCHA and allow Probely to bypass it successfully.

Suggested workflow

The cookie (implemented on your target) will check if the requests are being made using the configured header, disabling the CAPTCHAS and giving clear access to the target.

if (isset($_COOKIE['disable_captcha']) && $_COOKIE['disable_captcha'] === 'aaaaaffff5557777777cccccc99812333ab') {}

Possible cookie snippet. Note: Do not use the value of the cookie on this example.

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