CAPTCHA
A CAPTCHA is a challenge-response test designed to distinguish human users from automated programs.
Grokking Web Application Security
A CAPTCHA is an automated challenge-response test designed to distinguish human users from computer programs.
- How it is used
- Protects login, sign-up, and password-reset forms from simple brute-force automation and unwanted email triggering.
- How deep it goes
- Explains reCAPTCHA installation through hidden fields, token generation, and server-side verification, while noting bypasses rather than solving them.
- Examples
- Uses image-selection and distorted-text widgets, invisible reCAPTCHA signals, authentication forms, and a Ruby verification request.
- What you can do after
- Apply it via Google reCAPTCHA by generating form tokens and verifying them server-side without exposing the secret key.
Read how Grokking Web Application Security explains CAPTCHA →
Secure APIs
A CAPTCHA is an automated challenge-response test intended to distinguish human users from automated programs.
- How it is used
- Mitigates automated requests against sensitive business flows accessed through web applications.
- How deep it goes
- Explains CAPTCHA’s defensive role and limits but does not detail challenge implementation.
- Examples
- Illustrates CAPTCHA protecting an API designed for consumption by a web application.
- What you can do after
- Apply CAPTCHA challenges as one layer of protection against suspected automated activity.
Related concepts
- brute-force attackaddresses · A brute-force attack systematically tries numerous possible credentials, keys, inputs, or combinations until one succeeds or the search space is exhausted.
- WPFormsused by · WPForms is a WordPress plugin for creating contact forms with configurable features and fields.
- unrestricted access to sensitive business flowsaddresses · Unrestricted access to sensitive business flows is a vulnerability in which users or automated actors can abuse API-controlled business processes without adequate safeguards.
- GPT modelused by · A GPT model is a generative pretrained Transformer language model that produces text autoregressively by predicting successive tokens from preceding context.
- computer visionaddressed by · Computer vision is the field of computing concerned with using computational methods to extract and interpret information from images, video, and other visual data.
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