Antoine Vastel

This report uncovers how bot ecosystems harvest and reuse real browser fingerprints, including signals from commercial anti-bot systems, to scale realistic impersonation. These fingerprints are becoming operational assets, enabling more efficient and harder-to-detect automation. The implication is clear: detection systems must assume replay and treat client-side signals as untrusted.

How XRumer and XEvil scaled forum spam by combining automation, CAPTCHA solving, and brittle fingerprinting.