The updated Yandex anti-fraud system identifies and blocks some fraudsters even before the ad is shown. Previously, the system filtered "bot clicks" after the transition to the site, but now it analyzes behavioral signals and prevents the display of ads to bots and users with suspicious activity.
If a fraudster remains unrecognized at an early stage, the anti-fraud system will trigger at the moment of clicking on the ad and show such a user a "captcha". A successfully passed check opens access to the site — but the advertiser does not pay for such clicks and conversions. Fraudulent conversions also do not participate in the training of the advertising system algorithm. Yandex emphasized:
Thus, following the launch, the number of fraudulent conversions decreased by a factor of 2, and the number of fraudulent applications decreased by a factor of 3.5. At the same time, advertisers still only pay for real actions by real users.