What is MpSigStub.exe?

The .exe extension on a filename indicates an executable file. Executable files may, in some cases, harm your computer. Therefore, please read below to decide for yourself whether the MpSigStub.exe on your computer is a Trojan that you should remove, or whether it is a file belonging to the Windows operating system or to a trusted application.

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MpSigStub.exe file information

Windows Task Manager with MpSigStub
MpSigStub.exe process in Windows Task Manager

The process known as Microsoft Malware Protection Signature Update Stub belongs to software Microsoft Malware Protection by Microsoft (

Description: MpSigStub.exe is not essential for Windows and will often cause problems. The MpSigStub.exe file is located in a subfolder of C:\. Known file sizes on Windows 8/7/XP are 231,584 bytes (25% of all occurrences), 295,552 bytes and 4 more variants. 
The program is not visible. It is not a Windows core file. The software has no file description. Therefore the technical security rating is 53% dangerous, however you should also read the user reviews.

Recommended: Identify MpSigStub.exe related errors

If MpSigStub.exe is located in the C:\Windows\System32 folder, the security rating is 36% dangerous. The file size is 237,072 bytes (33% of all occurrences), 221,568 bytes or 231,584 bytes. The program has no visible window. It is certified by a trustworthy company. The file is not a Windows core file.
If you are having problems with MpSigStub.exe, you can do the following:
  1) remove the entire program Microsoft Corp. using Windows Control Panel
  2) ask the software vendor,, for advice.

Important: Some malware camouflages itself as MpSigStub.exe. Therefore, you should check the MpSigStub.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.


User Comments

The Forefront Client Security Antimalware Service updates the anti-malware engine files and the anti-malware definition files without leaving a gap in malware protection.
  Neil Tunnah   (further information)
It is part of the Windows Automatic Update tool.
  Sean Smith  
MpSigStub.exe is a Microsoft installer application used in conjunction with Windows Automatic Updates. It extracts update files to a temporary directory.
Microsoft Malware Protection Signature Update Stub
  Microsoft MVP   (further information)
It is required for Microsoft Windows Defender and I believe it is also needed for Microsoft Malware Removal Tool that is updated monthly. It is not Virus, Malware, Trojan, etc. When detected as such, report it as a false positive.
  Jenni L   (further information)
MpSigStub.exe is a MS installer application used in conjunction with Windows Automatic Updates. It extracts update files to a temporary directory.
  Alex   (further information)
MS Defender, MSMWRT, & Panda Cloud AV don't detect; McAfee does
stored in a random folder (in my case: E:\63bf18e751d3d39be7b19e12)
It was flagged by Bullguard as suspicious as it attempted to make a registry change
it is in a long random named folder started 2 days ago, i do not need it before so its trash
stored in an invisible folder on external hard drive I pluged in 3 secondes earlier, then realized it was the wrong hardrive, and tried to eject it. Zentimo said MpSigStub.exe was preventing the drive from ejecting, because it was running from a folder that did not exixt on the hard drive.
I believe there is a "real" file names MPSigStub" however mine was located in a random letter/number filename... deleted
on my pc it comes up automatic and seems to freeze the games that i am am playing which is very annoying
  bek strelley  
Mine is a virus. I had it in a random letters and numbers folder and now I can't delelte it.
It usually gets into my harddrive for some reason after i uninstall Norton. I can't remove it without network access authority.
I can neither conferm its danger or its harmlessness. I can not delete it from a second HDD fitted to my PC to hold lossless music files. I did manage to delete it earlier in the year by reformatting the HDD before reinstalling the lossless music files but as soon as Microsoft Updates came back in it reinstalled on the separate HDD.
It's in that folder in the root of c drive that not a suitable temporary location to be picked up by Disk Cleaner. Deleted.
It is in a randomly numbered folder on my secondary drive and I can't simply deleted. It says I need admin access but its my home computer
Mpsigstub.exe is store in a folder named 0a83a9928b30c2eebcbbb8 on my local disk (c) when i tried opening the folder it said i needed admin permissions. dont know if i should delete it or leave it. but by all these comments i might just keep it.
  Fernando L  

Rating chart

Summary: Average user rating of MpSigStub.exe: based on 21 votes with 19 user comments. 6 users think MpSigStub.exe is essential for Windows or an installed application. 2 users think it's probably harmless. 7 users think it's neither essential nor dangerous. 3 users suspect danger. 3 users think MpSigStub.exe is dangerous and recommend removing it. 4 users don't grade MpSigStub.exe ("not sure about it").

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Best practices for resolving MpSigStub issues

A clean and tidy computer is the key requirement for avoiding problems with MpSigStub. 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 doing a repair of your installation, or in the case of Windows 8, executing the DISM.exe /Online /Cleanup-image /Restorehealth command. This allows you to repair the operating system without losing data.

To help you analyze the MpSigStub.exe process on your computer, the following programs have proven to be helpful: Security 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. Malwarebytes Anti-Malware detects and removes sleeping spyware, adware, Trojans, keyloggers, malware and trackers from your hard drive.

Other processes

MpSigStub.exe [all]