How to remove the mssys virus

Most antivirus programs identify mssys.exe as malware.

The free file information forum can help you find out how to remove it. If you have additional information about this file, please leave a comment or a suggestion for other users.

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Mssys.exe file information

The process known as Microsoft® Windows® Operating System or Windows Services and Controller App belongs to software Microsoft® Windows® Operating System or Windows Services and Controller App or stub by Microsoft (

Description: Mssys.exe is not essential for Windows and will often cause problems. The file mssys.exe is located in a subfolder of C:\Windows. Known file sizes on Windows 10/8/7/XP are 1,032,192 bytes (50% of all occurrences) or 448,000 bytes. 
It is located in the Windows folder, but it is not a Windows core file. The program is not visible. The file is not a Windows core file. Mssys.exe is able to record keyboard and mouse inputs and monitor applications. Therefore the technical security rating is 63% dangerous.

Recommended: Identify mssys.exe related errors

If mssys.exe is located in the C:\Windows folder, the security rating is 100% dangerous. The file size is 933,299 bytes. It is a file with no information about its developer. It is an unknown file in the Windows folder. The program is not visible. The process starts upon Windows startup (see Registry key: MACHINE\Run, MACHINE\RunServices, MACHINE\RunOnceEx, MACHINE\RunOnce, win.ini, Winlogon\Shell). The application uses ports to connect to or from a LAN or the Internet. It is not a Windows system file. Mssys.exe is able to record keyboard and mouse inputs, monitor applications and manipulate other programs.

External information from Paul Collins:
There are different files with the same name:

Important: You should check the mssys.exe 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 mssys issues

The following programs have also been shown useful for a deeper analysis: Security Task Manager examines the active mssys process on your computer and clearly tells you what it is doing. Malwarebytes' well-known anti-malware tool tells you if the mssys.exe on your computer displays annoying ads, slowing it down. This type of unwanted adware program is not considered by some antivirus software to be a virus and is therefore not marked for cleanup.

A clean and tidy computer is the key requirement for avoiding PC trouble. This means running a scan for malware, cleaning your hard drive using cleanmgr and sfc /scannow, uninstalling programs that you no longer need, checking for Autostart programs (using msconfig) and enabling Windows' Automatic 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 resmon 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 DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

Other processes

mssys.exe [all]