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Has the file size of maintenanceservice_installer.exe changed above 157,698 bytes (security sw complains)?

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  • 3 zinale nkinga
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  • Igcine ukuphendulwa ngu dave_b

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In the past, my Firefox has updated automatically. This (I understand) means the file "maintenanceservice_installer.exe" has been running, allowing the dialog box that would ask me permission to update to be avoided. Now, today, my employer's security software complains that this file should be blocked, and do I want to allow it to run. This is consistent with the file signature having been changed (as by malware, such as from a couple on non-standard websites I visited yesterday). The actual file size on my disk is: 192, 768, dated Wed, 12/5/12 9:32:22 AM. But, checking on the Internet, this file has been known, in the past, to be 157, 608 bytes in size. So, has the file been intentially changed by Mozilla, or has my file been corrupted. If the latter, how should I proceed - delete the file, and would that cause that to be loaded again from the source?

Isisombululo esikhethiwe

Like Firefox itself, the Mozilla Maintenance service gets updated as well. You can check the current version by right-clicking maintenanceservice.exe and choosing Properties. This information can be found under the Details tab.

File size is not a very useful indicator of software authenticity. In the file properties window, check the Digital Signatures tab. If the signature is missing, invalid, or from someone other than “Mozilla Corporation”, then you have reason to worry.


The simplest thing to do is to download the Firefox installer and install on top of your current version while Firefox is closed. Your profile data (bookmarks, passwords, cookies and such) will not be affected.

The more complicated thing to do is

  1. Uninstall the Mozilla Maintenance Service from the Windows Control Panel.
  2. Delete the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Mozilla\MaintenanceService
  3. When Firefox is next updated, the maintenance service should be reinstalled automatically.
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Isisombululo Esikhethiwe

Like Firefox itself, the Mozilla Maintenance service gets updated as well. You can check the current version by right-clicking maintenanceservice.exe and choosing Properties. This information can be found under the Details tab.

File size is not a very useful indicator of software authenticity. In the file properties window, check the Digital Signatures tab. If the signature is missing, invalid, or from someone other than “Mozilla Corporation”, then you have reason to worry.


The simplest thing to do is to download the Firefox installer and install on top of your current version while Firefox is closed. Your profile data (bookmarks, passwords, cookies and such) will not be affected.

The more complicated thing to do is

  1. Uninstall the Mozilla Maintenance Service from the Windows Control Panel.
  2. Delete the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Mozilla\MaintenanceService
  3. When Firefox is next updated, the maintenance service should be reinstalled automatically.
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Thanks, gingerbread_man, for your sage advice. In my case, the digital signature was from Mozilla, so it's reasonable to think the file was updated by Mozilla itself. On the file size, though, while I agree that file size is not all that useful an indicator, it's nonetheless a red flag when the size of a file increases from its previous size. Just being careful. Thanks for the guidance. - dave_b