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Windows 7: Safe to remove many GB of accumulating Microsoft Antimalware files?

25 Oct 2014   #1

Safe to remove many GB of accumulating Microsoft Antimalware files?

My backup drive has gotten crammed full and I need to delete some old backups, but along the way, I see that some of the worst garbage accumulating is in c:\ProgramData\Microsoft Antimalware subdirectories.

Under .\Scans I see about 18 GB of files of the form mpcache-FC50A510897E3C2CD9FF30B4F4D8752A515DB662.bin.67 and the like.

There are another 10 GB of files under .\Definition Updates\

All told, this MSE pig has consumed over 15% of my disk.

Is this crapware (don't want to call it malware) that I can remove? How can I prevent it from accumulating? What is the proper procedure (e.g. services to turn off first? safe to delete the files, or entire subdirectory? will it automatically recreate as needed? etc.)

Thanks guys and gals.

After 30 some years of trying to polish Windows clean, got myself a shiny new Apple today. Next I will have to dig into how Microsoft profited so well last quarter.

My System SpecsSystem Spec
25 Oct 2014   #2

Windows 8

CCleaner ( has an option to clean MS Essentials and Windows Defender's folders automatically, you might want to check it.

Here is a link about what files exactly get deleted : Microsoft Security Essentials - CCleaner Bug Reporting - Piriform Community Forums
%CommonAppDAta% = C:\ProgramData\ in your case.

You can manually delete those if you don't want to install this application.

I'm not certain about the "Scans" and "Definition Updates" folders though. I assume deleting old definition updates is safe, but not certain.

You could try renaming them first to something like *.OLD and check if it still works. If it does than you can safely delete them for good.
My System SpecsSystem Spec

 Safe to remove many GB of accumulating Microsoft Antimalware files?

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