Implementation Vulnerability

CAPTCHA Implementation Vulnerability

Overview of the Vulnerability

A Computer Automated Public Turing Test test to tell Computers and Humans Apart (CAPTCHA) allows applications to tell whether a user is a human or a robot. A CAPTCHA can be bypassed when the implementation or its workflow is misconfigured, or when software can be used to bypass the challenge.

An attacker can leverage scripts and tools to bypass the CAPTCHA and make requests to critical functionality without a rate limit. Forms that are often firewalled by a CAPTCHA can also deny service for users when executing multiple read and write functions from the database.

Business Impact

CAPTCHA misconfiguration can lead to reputational damage for the business due to a loss in confidence and trust by users.

Steps to Reproduce

  1. Navigate to the following endpoint with CAPTCHA: {{value}}

  2. Use {{software}} to bypass CAPTCHA

Proof of Concept (PoC)

The screenshot(s) below demonstrates the CAPTCHA being bypassed:

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Recommendation(s)

The configuration of CAPTCHAs should be thoroughly tested for design and implementation flaws to prevent an attacker bypassing the CAPTCHA.

For more information, please see:

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