What is usbstor?

Usbstor.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 usbstor.sys is a Windows system file or if it belongs to an application that you can trust.

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

Usbstor.sys file information

The process known as USB Mass Storage Class Driver or USB-Massenspeichergerät-Klassentreiber belongs to software Microsoft Windows Operating System or Betriebssystem Microsoft Windows by Microsoft (

Description: The original usbstor.sys is an important part of Windows and rarely causes problems. Usbstor.sys is located in the C:\Windows\System32\drivers folder. Known file sizes on Windows 10/8/7/XP are 26,368 bytes (42% of all occurrences), 76,288 bytes or 26,496 bytes. 
The driver can be started or stopped from Services in the Control Panel or by other programs. The program has no visible window. It is a Microsoft signed file. There is no detailed description of this service. usbstor.sys appears to be a compressed file. Therefore the technical security rating is 1% dangerous, however you should also read the user reviews.

Recommended: Identify usbstor.sys related errors

Important: Some malware disguises itself as usbstor.sys, particularly when not located in the C:\Windows\System32\drivers folder. Therefore, you should check the usbstor.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.


User Comments

Driver for a six-in-one storage card reader (external)
Microsoft's driver for USB interface with storage devices.
  Jason F.  
i neden windows 98 se dont have it it says that is in
This has to be the most bug ridden file that microsoft have ever released :@ my version re-sets my computer every time its loaded apart from when i insert an empty card reader 1st.
Reading it from the hard drive during startup holds up my boot times by about 15 seconds.
  Raymond Lee MSc  
cuz im missing it and i need it, to run my camera-usb driver
It's used to enable or disable USB storage devices for System Admins.
It likes to break sometimes when you update Windows.
It is used for USB storage devices lke external hardrives and is stored in %sysfolder%\system32\drivers
  Kevin Balenzuela   (further information)
I have an usb storage devise it's new but I can't format it or do any other action
My USB flash disk does not detect on my computer
It's a process that contros USB flash drives and external hard drives
usbstor driver for windows xp
Avast Found it Virus
scanned it with F-secure and USBSTOR shutted it down.
Driver required to run usb storage devices

Rating chart

Summary: Average user rating of usbstor.sys: based on 30 votes with 18 user comments. 23 users think usbstor.sys is essential for Windows or an installed application. 2 users think it's probably harmless. 2 users think it's neither essential nor dangerous. One user suspects danger. 2 users think usbstor.sys is dangerous and recommend removing it. 4 users don't grade usbstor.sys ("not sure about it").

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Best practices for resolving usbstor issues

A clean and tidy computer is the key requirement for avoiding problems with usbstor. 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 usbstor.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

usbstor.sys [all]