How Anti‑Cheat SDKs Work (Kernel vs User Mode)

What Do “User Mode” and “Kernel Mode” Actually Mean?

On Windows, code runs in two broad privilege levels:

• User mode: where apps live. If something crashes here, it usually doesn’t take down the whole OS. Access to system memory and other processes is restricted.
• Kernel mode: where core OS components and drivers run with full system privileges. A crash here can blue‑screen the system, but this level has the visibility/power to monitor tampering at a deeper layer.

Why anti‑cheat cares: Cheats can hook game processes, drivers, and even the boot process. If anti‑cheat only lives in user mode, sophisticated cheats can hide beneath it. Kernel‑mode components are harder to evade—though not impossible—and can watch for low‑level manipulations.

⚙️ Live production tech can get tricky. We break down NDI vs SRT vs RTMP in simple terms so you know which protocol to pick.

How Anti‑Cheat SDKs Work at a High Level

Most modern stacks combine:

1. A client component that loads with the game to check integrity, watch for injected code, and enforce rules.
2. (Optionally) a kernel driver to observe privileged operations (e.g., suspicious drivers, memory tampering, hypervisor tricks).
3. Server‑side analytics and mitigations (shadow bans, “damage shields,” cloaking cheaters from others) that react to detections without ruining normal players’ matches.

Vendors vary in how long their components run. For example, EAC’s Windows service starts when an EAC‑protected game starts and stops when the game stops; RICOCHET’s kernel driver only operates while you’re playing.

Examples of Popular Anti-Cheat Systems

Riot Vanguard (VALORANT, League of Legends)

• What it is: Riot’s in‑house game security platform with a client + kernel‑mode driver.
• How it runs: Riot recently added a system‑tray toggle so players can disable Vanguard when not gaming; to play again, you must re‑enable (often via reboot), and games protected by Vanguard will not launch if it’s disabled.
• Why kernel: to observe deeper tampering that user‑mode tools might miss. (Riot positions privacy and safety as core design constraints in its support docs.)

Activision RICOCHET (Call of Duty)

• What it is: A multi‑layer anti‑cheat with a PC kernel‑level driver plus server‑side mitigations (e.g., Damage Shield, Cloaking) that degrade confirmed cheaters’ effectiveness.
• How it runs: Not always on; the driver starts with the game and stops when you exit.

Easy Anti‑Cheat (EAC)

• What it is: Widely used anti‑cheat from Epic.
• How it runs: On Windows, EAC includes a service component that starts with a protected game and stops when it stops.
• Modern security prerequisites: Games using EAC may require Secure Boot, TPM 2.0, or IOMMU (VT‑d/AMD‑Vi)—especially in ranked/competitive modes or for high‑risk accounts—to make boot‑level and DMA hardware cheats harder. (Exact requirements are set by each game.)

BattlEye

• What it is: A long‑running anti‑cheat used by titles like DayZ, Tarkov, and others.
• How it runs: Uses a Windows driver commonly known as BEDaisy.sys; when that driver can’t load (e.g., due to certain Windows security features), you’ll see specific driver‑load errors. This indicates the system is relying on kernel‑mode capabilities.

Valve Anti‑Cheat (VAC)

• What it is: Valve’s system for VAC‑secured servers.
• How it runs: Automated, signature‑based detection; if cheats are identified while connected to a VAC‑secured server, the account is banned from that game’s VAC‑secured servers going forward. (Valve does not publish details about driver privilege levels.)

Kernel-Level vs User-Mode Anti-Cheat: Detailed Comparison

At a glance: Kernel-mode anti-cheat offers deeper system visibility for detecting low-level cheats, but it also carries greater responsibility for maintaining stability, safeguarding user privacy, and ensuring transparent communication about data access. [Microsoft Learn, Activision RICOCHET, EAC Security Docs]

Sources for table claims: Microsoft Learn — User vs Kernel Mode, Activision RICOCHET Overview, Easy Anti-Cheat — Security Requirements, [Vendor driver documentation & community-reported stability issues].

Modern Gaming Security Requirements: TPM 2.0, Secure Boot, IOMMU, and DMA Protections Explained

• Secure Boot blocks unsigned/unauthorized code at boot so cheats can’t slip in before Windows starts.
• TPM 2.0 helps attest that those boot settings really were enforced (measured boot), so “fake” Secure Boot states are harder to forge.
• IOMMU (Intel VT‑d / AMD‑Vi) gives the OS control over Direct Memory Access (DMA) from PCIe devices used in hardware‑based cheats that read game memory from a second PC.
  These features don’t necessarily run during gameplay; they validate boot integrity and constrain DMA, raising the bar for whole classes of cheats. Vendors increasingly allow (or require) games to enforce them.

Concrete trend: in 2025, reporting highlighted Call of Duty: Black Ops 7 and Battlefield 6 enforcing Secure Boot + TPM 2.0 on PC to harden anti‑cheat.

Steam’s Kernel-Level Anti-Cheat Policy and the Future of Game Security Standards

• Steam’s disclosure label (Oct 31, 2024): Valve surfaces kernel-level anti-cheat on Steam store pages and requires developers to disclose it in the Steamworks release flow.
• Linux/Steam Deck compatibility: Publishers sometimes disable Linux/Proton access where their threat model isn’t met; for example, On Nov 1, 2024, Apex Legends blocked Linux/SteamOS access (affecting Steam Deck) citing anti‑cheat abuse from Linux environments.

Privacy, Risks, and Ethical Concerns Around Kernel-Mode Anti-Cheat Drivers

Academic and security research has examined whether kernel-level anti-cheat resembles “rootkit-like” behavior and what guardrails are appropriate.

A 2024 academic paper—If It Looks Like a Rootkit and Deceives Like a Rootkit (Dorner & Klausner)—argued that some kernel-level anti-cheats exhibit rootkit-like properties and urged greater transparency, third-party audits, and careful driver design to balance privacy protection with fair-play enforcement.

This is not a blanket indictment; it’s a reminder that high-privilege software must be carefully audited, clearly disclosed, and kept as minimal as possible.

Vendor transparency:

• RICOCHET documents what its driver observes (processes that interact with COD titles) and emphasizes that the driver runs only while the game runs.
• Riot publishes support notes on what Vanguard is and provides user controls (tray toggle, uninstall/reinstall).

Real-World Anti-Cheat Systems: Vanguard, RICOCHET, EAC, BattlEye, and VAC Explained

Here’s how today’s most popular anti-cheat SDKs operate in real games — from kernel-level drivers to user-mode services — and how each balances performance, privacy, and protection.

• Riot Vanguard: client + kernel driver; tray‑icon toggle; must be enabled to play Vanguard‑protected games.
• RICOCHET (COD): kernel driver that runs only during gameplay + server‑side mitigations (Damage Shield, Cloaking, Disarm, etc.).
• EAC: Windows service starts/stops with the game; games may require Secure Boot/TPM/IOMMU to resist boot‑time/DMA cheats.
• BattlEye: uses BEDaisy.sys driver on Windows (kernel‑mode); driver‑load issues are commonly documented across support forums.
• VAC: signature‑based detection for VAC‑secured servers; bans apply to VAC‑secured play for that game.

FAQ About Kernel-Level and User-Mode Anti-Cheat Systems

Is kernel‑level anti‑cheat “always on”?

No—this depends on the vendor. RICOCHET’s driver runs only when a COD title is running. Vanguard can be turned off from the system tray, but you must re‑enable (and often reboot) to play protected games.

Why does my game require Secure Boot and/or TPM 2.0?

To validate boot integrity and prevent cheats that inject before Windows loads; in 2025, COD: Black Ops 7 and Battlefield 6 announced enforcement of these features on PC.

Does kernel‑level anti‑cheat tank performance?

Implemented correctly, these checks primarily occur at startup/validation, not in the render loop;Activision communicated that enabling TPM 2.0 and Secure Boot for COD shouldn’t affect in‑game performance; these checks are about boot integrity rather than per‑frame gameplay. Actual impact varies by implementation and system configuration.

What about Linux/Steam Deck?

Threat models differ. Some publishers restrict access if they can’t meet their risk tolerance under Proton/Linux. Apex Legends explicitly dropped Steam Deck/Linux support citing anti‑cheat concerns.

What data do these systems collect?

Varies. RICOCHET describes monitoring processes that interact with the game to identify tampering; Riot points to privacy notices for data handling. Always review each vendor’s documentation and your region’s privacy notices.

Practical Guidance for Readers

If you’re a player

• Expect transparency labels on Steam for kernel‑mode anti‑cheat. If you’re uncomfortable with high‑privilege software, check the store page before buying.
• Enable platform security (Secure Boot, TPM 2.0) if your game requires it; this is becoming more common in competitive shooters.
• Know your controls: Vanguard can be toggled from the tray when you’re not playing; some systems only run while the game runs (RICOCHET, EAC service).

If you’re a developer or technical decision‑maker

• Align mode to threat model: user‑mode checks are lighter‑weight but easier to evade; kernel‑mode components raise the bar against sophisticated cheats, DMA tools, and boot‑level tampering.
• Harden the platform path: document and, where justified, require Secure Boot, TPM 2.0, and IOMMU in competitive contexts. Provide clear troubleshooting guides.
• Minimize and disclose: publish clear runtime behavior (when drivers run, what is inspected) and follow least‑privilege principles. Steam’s kernel-level label means players will scrutinize these drivers closely; clear disclosure builds long-term trust.
• Plan mitigations (not just bans): techniques like cloaking, damage shields, and disarming can preserve match integrity while you investigate.
• Engage with research & audits: the 2024 ARES paper highlights how some implementations mirror rootkit techniques; independent reviews and bug bounties reduce risk.

Closing Thought

Kernel‑level anti‑cheat is not a silver bullet—but for the most targeted games, it’s become part of a layered security posture alongside attested boot, device‑control (IOMMU), and server‑side mitigations. The practical question isn’t “kernel vs user” in isolation—it’s which mix of privileges, platform features, and operational transparency gives your game the best integrity with the least surprise to players.

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References & Further Reading

• Microsoft Learn. “User Mode and Kernel Mode.” (Windows Architecture Overview)
• Riot Games. “What Is Vanguard?” and “2XKO Vanguard Information.” Official Support Pages.
• Activision Blizzard. “RICOCHET Anti-Cheat: Kernel-Level Driver Overview and Mitigations.” Official COD Blog.
• Easy Anti-Cheat (Epic Games). “Windows Service Lifecycle” and “Additional Security Requirements (TPM, Secure Boot, IOMMU).”
• BattlEye. “BattlEye FAQ” and developer documentation referencing the BEDaisy.sys driver.
• Valve / Steam Support. “Valve Anti-Cheat (VAC) System Overview.”
• Valve Steamworks Announcement. “Kernel-Level Anti-Cheat Disclosure Label,” October 31 2024.
• Gaming Press (2025). Reports on Call of Duty: Black Ops 7 and Battlefield 6 requiring TPM 2.0 + Secure Boot (The Verge / Tom’s Hardware, Nov 2025).
• Dorner, S. & Klausner, M. (2024). *If It Looks Like a Rootkit and Deceives Like a Rootkit: An Analysis of Kernel-Level Anti-Cheat Drivers.* ARES Conference Paper.