http.sys

What is http.sys?

http.sys is Windows' kernel-mode HTTP listener that accepts and routes incoming HTTP requests for IIS and other Windows networking components. It runs in kernel space to minimize context switches and improve throughput, handling connections at the earliest point in the network stack before they reach user‑mode processes.

HTTP.sys processes requests in the kernel, dispatching them to user-mode workers or apps. It provides efficient queuing, TLS handling, and security filtering, enabling scalable web hosting on Windows.

Types of HTTP.sys Tasks

• Kernel Listener: Listens for incoming HTTP connections at the system level (ports 80/443) and dispatches requests.
• Request Router: Routes requests to appropriate worker processes or apps.
• Security Filter: Applies authentication and TLS checks before handing off.
• Lifecycle Manager: Manages binding lifetimes, back pressure, and connection limits.
• Performance Optimizer: Coordinates connection pooling and caching with the Windows HTTP stack.

Is http.sys Safe?

Yes, http.sys is safe when it is the genuine Microsoft kernel driver included with Windows and not tampered with.

Is http.sys a Virus or Malware?

The real http.sys is NOT a virus. Malware can masquerade as system files, so verification is important.

How to Tell if http.sys is Legitimate

1. File Location: Ensure the file is at C:\Windows\System32\drivers\http.sys.
2. Digital Signature: Right-click http.sys in File Explorer -> Properties -> Digital Signatures. Should show "Microsoft Windows" as signer.
3. Resource Usage: Kernel driver should show minimal user-mode CPU usage; monitor via Performance Monitor or Resource Monitor.
4. Behavior: HTTP.sys should be loaded automatically by the System, not run as a standalone user-mode process.

Why Is http.sys Running on My PC?

http.sys runs to support Windows HTTP services. It loads during boot or when IIS and related services start to listen for HTTP requests on the system.

Reasons it's running:

• Active IIS or HTTP listeners: IIS or other HTTP-based services use HTTP.sys to accept and dispatch requests.
• Kernel-mode processing: HTTP.sys handles request parsing and queuing in the kernel to reduce context switches.
• Startup integration: Windows loads http.sys at startup to ensure web services are ready on demand.
• TLS and security filtering: TLS termination and early authentication are performed by HTTP.sys as part of the security stack.
• High network demand: On busy servers, HTTP.sys scales by pooling worker threads for concurrent connections.

Can I Disable or Remove http.sys?

NO http.sys is a core Windows kernel component required by IIS and the Windows networking stack.

How to Stop http.sys

• Disable IIS features: Turn off IIS or stop web services in Windows Features or Services.msc to reduce http.sys activity.
• Disable related apps: Stop apps that explicitly rely on HTTP.sys like IIS, Web Deploy, or other web servers.
• Configure server to minimize load: Adjust application pool limits and request queue length in IIS Manager.
• Restart Windows services: Restart the System or specific web services to reset http.sys activity.
• Monitor but do not remove: Keep Windows networking components enabled; you can disable specific site bindings or ports if necessary.

How to Uninstall http.sys

• ✔ There is no supported method to remove http.sys because it is part of Windows. Consider disabling dependent services (IIS, WebDAV) and turning off features you don't need.
• ✔ If you suspect tampering, run System File Checker: sfc /scannow from an elevated command prompt and apply Windows Updates to repair components.
• ✔ For complete removal, a repair install or OS reinstallation is required.

Common Problems: HTTP.sys Related Issues

If http.sys-related components are acting up, use these causes and solutions to triage common server-side HTTP issues.

Common Causes & Solutions

• IIS or HTTP services misconfiguration: Open IIS Manager and verify site bindings, app pools, and request queue length; reset on changes.
• High request volume: Enable request queuing, tune worker process limits, and consider load balancing.
• Outdated Windows/HTTP components: Install pending Windows Updates to refresh http.sys and security fixes.
• TLS certificate or cipher misconfiguration: Verify certificate bindings, update TLS settings, and ensure Schannel config matches clients.
• Port conflicts with another service: Check listening ports (netstat -ano) and rebind IIS sites or stop conflicting services.
• Corrupted driver or system files: Run sfc /scannow and DISM to repair system files; consider repair install if needed.

Related Processes