Anti-cheat software historically ran entirely in usermode (Ring 3), the same privilege level as the game and most applications. This made it easier to develop and safer to deploy, but it also meant the anti-cheat could be blinded or manipulated by anything else running at the same or higher privilege level.
Why Kernel-Mode (Ring 0)
By installing a signed kernel driver, anti-cheat vendors like Easy Anti-Cheat and BattlEye gain visibility into system activity that usermode software cannot see or control — including other drivers, raw hardware access attempts, and low-level process manipulation. This closes off an entire category of attacks that relied on hiding from a weaker vantage point.
Trade-offs
Kernel-mode anti-cheat is more invasive, requires a driver signed by Microsoft, and has drawn public scrutiny over privacy and system stability — most notably during the 2020 launch of Riot Games' Vanguard driver, which sparked debate about always-on kernel monitoring.
Conceptual Scope Note
This page describes architectural motivation only. It intentionally does not enumerate specific kernel APIs, driver communication mechanisms, or memory-access primitives, as that level of detail functions as implementation guidance rather than education.