What is cbfs4?

Cbfs4.sys is a Windows driver. A driver is a small software program that allows your computer to communicate with hardware or connected devices. This means that a driver has direct access to the internals of the operating system, hardware etc. The free file information forum can help you determine if cbfs4.sys is a Windows system file or if it belongs to an application that you can trust.

Run a free scan to check for cbfs4 drivers in need of updating

Cbfs4.sys file information

The process known as Callback File System Driver belongs to software Callback File System by EldoS (

Description: Cbfs4.sys is not essential for the Windows OS and causes relatively few problems. Cbfs4.sys is located in a subfolder of "C:\Program Files\Common Files". The file size on Windows 10/8/7/XP is 385,728 bytes. 
The driver can be started or stopped from Services in the Control Panel or by other programs. The program has no visible window. The cbfs4.sys file is a Verisign signed file. The cbfs4.sys file is certified by a trustworthy company. The service has no detailed description. Cbfs4.sys is not a Windows system file. cbfs4.sys appears to be a compressed file. Therefore the technical security rating is 20% dangerous.

Recommended: Identify cbfs4.sys related errors

If cbfs4.sys is located in the C:\Windows\System32\drivers folder, the security rating is 20% dangerous. The file size is 323,392 bytes. The program is not visible. The cbfs4.sys file is a Verisign signed file. It is certified by a trustworthy company. There is no detailed description of this service. Cbfs4.sys is not a Windows system file. cbfs4.sys appears to be a compressed file.

Important: Some malware camouflages itself as cbfs4.sys. Therefore, you should check the cbfs4.sys process on your PC to see if it is a threat. We recommend Security Task Manager for verifying your computer's security. This was one of the Top Download Picks of The Washington Post and PC World.


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Best practices for resolving cbfs4 issues

A clean and tidy computer is the key requirement for avoiding problems with cbfs4. This means running a scan for malware, cleaning your hard drive using 1cleanmgr and 2sfc /scannow, 3uninstalling programs that you no longer need, checking for Autostart programs (using 4msconfig) and enabling Windows' 5Automatic Update. Always remember to perform periodic backups, or at least to set restore points.

Should you experience an actual problem, try to recall the last thing you did, or the last thing you installed before the problem appeared for the first time. Use the 6resmon command to identify the processes that are causing your problem. Even for serious problems, rather than reinstalling Windows, you are better off repairing of your installation or, for Windows 8 and later versions, executing the 7DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the cbfs4.sys process on your computer, the following programs have proven to be helpful: ASecurity Task Manager displays all running Windows tasks, including embedded hidden processes, such as keyboard and browser monitoring or Autostart entries. A unique security risk rating indicates the likelihood of the process being potential spyware, malware or a Trojan. BMalwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

cbfs4.sys [all]