Amazon WAF CAPTCHA puzzles
Amazon WAF provides standard CAPTCHA functionality that challenges users to confirm that they are human beings. CAPTCHA stands for Completely Automated Public Turing test to tell Computers and Humans Apart. CAPTCHA puzzles are designed to verify that a human is sending requests and to prevent activity like web scraping, credential stuffing, and spam. CAPTCHA puzzles can't weed out all unwanted requests. Many puzzles have been solved using machine learning and artificial intelligence. In an effort to circumvent CAPTCHA, some organizations supplement automated techniques with human intervention. In spite of this, CAPTCHA continues to be a useful tool to prevent less sophisticated bot traffic and to increase the resources required for large-scale operations.
Amazon WAF randomly generates its CAPTCHA puzzles and rotates through them to ensure that users are presented with unique challenges. Amazon WAF regularly adds new types and styles of puzzles to remain effective against automation techniques. In addition to the puzzles, the Amazon WAF CAPTCHA script gathers data about the client to ensure that the task is being completed by a human and to prevent replay attacks.
Each CAPTCHA puzzle includes a standard set of controls for the end user to request a new puzzle, switch between audio and visual puzzles, access additional instructions, and submit a puzzle solution. All puzzles include support for screen readers, keyboard controls, and contrasting colors.
The Amazon WAF CAPTCHA puzzles meet the requirements of the Web Content Accessibility Guidelines
(WCAG). For information, see Web Content
Accessibility Guidelines (WCAG) Overview