Darknet Sites Use Complex CAPTCHAs to Block Automated Access

Summary

DarkOwl describes CAPTCHA designs on darknet markets and forums, including language, image, logic, and timed challenges used to impede bots and make sites harder for researchers and law enforcement to access or crawl.

Key points

• Darknet sites use CAPTCHAs to restrict automated traffic, including crawling and other malicious activity.
• Examples include Cyrillic character entry, odd-one-out image puzzles, changing pixels, and timed challenges.
• Other designs require solving math problems, identifying missing images, reading a clock, or following character-selection prompts.
• Some challenges use multiple steps or highlight characters to enter in order to help users verify they are on the intended site.
• The article says these CAPTCHAs can impede security researchers and law enforcement seeking to access or scrape darknet sites.