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MSFT MRT Removes mbshlext.dll?

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I'm sorry if I've missed a discussion on this, but I'm surprised it isn't making more waves.

Ever install a Windows Update only to have your Scan with Malwarebytes context menu in Explorer disappear?  It appears that Microsoft's Malicious Software Removal Tool is just deleting a key component of Malwarebytes:  mbshlext.dll

After Windows Updates I have to go restore mbshlext.dll from one of my backups to its former home in folder C:\Program Files\Malwarebytes\Anti-Malware.

Sure seems rather anti-competitive to me...


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I have before and after listings from the following SysInternals AutoRuns command:

autorunsc64 -a *

The one just before the application of cumulative Windows 8.1 updates on June 15 at 7am showed this:

     c:\program files\malwarebytes\anti-malware\mbshlext.dll
     1/25/2017 5:37 PM

The one just after the update showed this:

     File not found: C:\Program Files\Malwarebytes\Anti-Malware\mbshlext.dll


Do you know of specific logs emitted by the MRT?  I'll be happy to dig into them.


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I can't offer any other reason a Windows Update should remove the above mentioned file, but MRT didn't log the deletion.  That being said, it's certain that the Windows Update process is what caused it.  It's not the first time I've seen it happen during a Windows Update (I compare my AutoRuns output every time I run a Windows Update).  This is the pertinent section of the MRT log.

Microsoft Windows Malicious Software Removal Tool v5.61, June 2018 (build 5.61.14929.3)
Started On Fri Jun 15 07:14:11 2018

Engine: 1.1.14901.4
Run Mode: Scan Run From Windows Update

Results Summary:
No infection found.
Microsoft Windows Malicious Software Removal Tool Finished On Fri Jun 15 07:16:40 2018

Return code: 0 (0x0)


I can only guess that if they're engaging in anti-competitive behavior they wouldn't log it.


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I seem to have accumulated a lot of stuff in there.

Bear in mind this was not a Windows in-place upgrade.  I brought a Win 8.1 x64 Pro MCE system up to date from December patch level to June patch level.

Any particular folder you'd like me to send you from this set?

C:\TEMP>dir C:\Windows\Panther /s
 Volume in drive C is C - NoelC4 SSD
 Volume Serial Number is 00ED-C11E

 Directory of C:\Windows\Panther

11/13/2013  01:05 PM    <DIR>          .
11/13/2013  01:05 PM    <DIR>          ..
11/13/2013  12:07 PM            42,475 cbs.log
11/13/2013  12:08 PM                68 Contents0.dir
11/13/2013  12:13 PM                68 Contents1.dir
11/13/2013  12:11 PM             2,844 DDACLSys.log
11/13/2013  12:13 PM             5,718 diagerr.xml
11/13/2013  12:13 PM            16,086 diagwrn.xml
11/13/2013  01:05 PM    <DIR>          FastCleanup
11/13/2013  12:08 PM            28,812 MainQueueOnline0.que
11/13/2013  12:13 PM            27,456 MainQueueOnline1.que
11/13/2013  01:05 PM           434,176 setup.etl
11/13/2013  12:11 PM    <DIR>          setup.exe
11/13/2013  12:13 PM           540,754 setupact.log
11/13/2013  11:59 AM                 0 setuperr.log
11/13/2013  12:08 PM           440,576 setupinfo
11/13/2013  12:11 PM    <DIR>          UnattendGC
08/22/2013  07:18 AM           929,792 _s_AEE9.tmp
08/22/2013  08:41 AM           442,772 _s_B40C.tmp
              14 File(s)      2,911,597 bytes

 Directory of C:\Windows\Panther\FastCleanup

11/13/2013  01:05 PM    <DIR>          .
11/13/2013  01:05 PM    <DIR>          ..
11/13/2013  01:05 PM             1,908 diagerr.xml
11/13/2013  01:05 PM             1,908 diagwrn.xml
11/13/2013  01:05 PM               456 setupact.log
11/13/2013  01:05 PM                 0 setuperr.log
               4 File(s)          4,272 bytes

 Directory of C:\Windows\Panther\setup.exe

11/13/2013  12:11 PM    <DIR>          .
11/13/2013  12:11 PM    <DIR>          ..
               0 File(s)              0 bytes

 Directory of C:\Windows\Panther\UnattendGC

11/13/2013  12:11 PM    <DIR>          .
11/13/2013  12:11 PM    <DIR>          ..
11/13/2013  01:05 PM             4,123 diagerr.xml
11/13/2013  01:05 PM             3,813 diagwrn.xml
11/13/2013  01:05 PM            58,469 setupact.log
11/13/2013  01:05 PM               123 setuperr.log
               4 File(s)         66,528 bytes

     Total Files Listed:
              22 File(s)      2,982,397 bytes
              11 Dir(s)  605,448,335,360 bytes free


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Thanks, Devin.  Let me know if there's anything more I can do.

Oh, and could you please verify that the version of the dll ( that I restored from my backup is the one that's supposed to go with the latest MWB package (


Edited by NoelC
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