Adaptive Captcha

ALTCHA Sentinel includes a feature called Adaptive Captcha that enables frictionless verification for legitimate users while enforcing a code challenge for high-risk users or those who have misbehaved recently.

Feature Highlights

• Provides frictionless verification for legitimate users with additional checks for flagged users
• Implements code challenges as an additional obstacle for bots and suspicious users
• Offers accessible, WCAG-compliant audio playback options for assistive technologies
• Automatically managed by Autopilot

Code Challenge Example

This demonstration shows the interface of the code challenge presented to flagged users:

Note: This is a demonstration showing only the user interface without full functionality.

How Adaptive Captcha Works

The system evaluates multiple factors during each verification, using the combined score to determine whether to require the additional code challenge.

Evaluated factors include:

• Bot activity: Activated when bots, crawlers, or AI agents are detected
• Suspicious networks: Triggered when connecting from malicious or TOR networks
• High-risk countries: Activated for connections originating from high-risk locations
• Non-standard browsers: Triggered when standard headers are missing or contain unusual values
• User penalties: Includes recent penalties for misbehavior like excessive requests
• Server load: Triggered during high-traffic periods when the server is under stress

Accessibility

To maintain accessibility with assistive technologies such as screen readers, audio playback of the challenge code is available. The audio supports multiple languages to accommodate users worldwide.

Supported Languages

Since the code is always generated using only the Latin alphabet, some languages are not supported, and the audio challenge defaults to English instead.

The audio challenge supports the following languages:

• Afrikaans (af)
• Bosnian (bs)
• Czech (cs)
• Croatian (hr)
• Danish (da)
• Dutch (nl)
• English (en)
• Estonian (et)
• Finnish (fi)
• French (fr)
• German (de)
• Hungarian (hu)
• Icelandic (is)
• Indonesian (id)
• Irish (ga)
• Italian (it)
• Latvian (lv)
• Lithuanian (lt)
• Maltese (mt)
• Norwegian Bokmål (nb)
• Polish (pl)
• Portuguese (pt)
• Romanian (ro)
• Serbian (sr)
• Slovak (sk)
• Slovenian (sl)
• Spanish (es)
• Swedish (sv)
• Turkish (tr)
• Vietnamese (vi)

Enabling Adaptive Captcha

You can configure Adaptive Captcha settings in each Security Group within Sentinel.

There are two ways to enable Adaptive Captcha:

1. Autopilot: When enabled, this feature automatically manages adaptive captcha as needed
2. Manual configuration: If not using Autopilot:
   • Enable the Code Challenge feature
   • Activate Adaptive Mode