Question Windows 10 quick scan only 43 files and last 5 seconds all of a sudden

Sep 18, 2019
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Whereas the quick scan would scan several thousand files and take around a minute or so. Also, "Tamper Protection" was somehow disabled on its own. I immediately enabled it but that raised an eyebrow.

Googling this for the past ~40 minutes to no avail. Went to the Science and Tech section on Twitch with the hopes I could get a quick response and was advised to perform a windows refresh/reset.

This is just strange to me. Any thoughts?
 
Are you referring to the 'quick scan option'/default option within and by Windows Security/Defender, or with some other AV solution?

I do not even see the option to manipulate that/exclude certain locations within Windows Defender Quick Scan option, even if one actually desired to ....

You are right to be concerned, if not an outright breech, some application did this for a reason...; any newly installed software from questionable sources, or, might some other user have been possibly tricked into one of the infamous 'Adobe Flash Updates'?

Even with an M.2 NVME drive, a Defender quick scan takes me 30 seconds...

When in doubt...scan with both Roguekiller64 and Malwarebytes Antimalware....
 
Sep 18, 2019
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Within Windows Defender in Virus & Threat protection. I hit the "Quick scan" every single time after booting up and always right after I run a Malwarebytes scan. The quick scan always scans several thousand files in around a minute or so... until today.

I haven't visited any questionable or nefarious sites or d/l'ed anything of the sort to the best of my recollection. But now that you mention it, I seem to vaguely remember installing an Adobe Flash update for some reason while using Foxfire. But that would've been a few days ago.

Not familiar with Roguekiller64 but will check it out right now. I'm really getting stressed out about this. Thanks for helping out.

ETA: I forgot to mention that I tried running Windows offline scan twice and although it did reboot my pc, it never appeared at all to do any kind of scan and upon rebooting it never led me to any results. Checked the "Protection history" under Virus and Threat protection and that had 0 results. Also ran MB anti-rootkit which found nothing.
 
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Sep 18, 2019
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Installed and ran Roguekiller64. Nothing detected. Continued running the full scan in Defender and same result: only 43 files scanned in 5 seconds. Ran a custom scan on my c: and e: folder. Those scanned all the files and took the expected corresponding amount of time to do it. Nothing detected.

Searched for Adobe in control panel/programs to uninstall it but it doesn't show that it has been installed.

Yet, after all this, both quick and full scans in Windows Defender still completes in 5 seconds with only 43 files scanned. I just don't know what to make of it.
 
Sep 18, 2019
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Same here with me... After a update to Windows Defender now my scan last 7 seconds, be it Full Scan or Quick Scan, and only 48 files are verified. Strange...
 
Sep 18, 2019
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I already did a scan with Malwarebytes and Nod32 Antivirus and nothing was found. So I tried to search on Google and here I am now...

Well, I think Microsoft did something really speacial with WD...
 
Sep 18, 2019
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Same here with me... After a update to Windows Defender now my scan last 7 seconds, be it Full Scan or Quick Scan, and only 48 files are verified. Strange...
Was your "Tamper Protection" disabled by any chance? Windows Security>Virus & Threat protection>Virus & Threat protection settings>Manage settings. Should be the fourth one down.

Glad you replied. Let's me know it isn't just me all of a sudden.
 
Sep 18, 2019
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Was your "Tamper Protection" disabled by any chance? Windows Security>Virus & Threat protection>Virus & Threat protection settings>Manage settings. Should be the fourth one down.

Glad you replied. Let's me know it isn't just me all of a sudden.
I checked now the Tamper Protection... No, it wasn't disabled.

My hardware is a Core i5 3570, 16GB RAM Kingston, a GTX 1050 and a Kingston SSD A400 240GB... If it helps in some way.

Before the full scan last 23 to 25 minutes. So I was really surprised today when last only 7 seconds...

This is the only thread I found talking about it.

My guess is the new update in some way did it with Windows Defender, but I cannot understand why now it scan only 48 files.

I hope someone clarify it to us...
 
Sep 18, 2019
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Ok, my Tamper Protection was oddly disabled for whatever reason...

Yeah, prior to posting here, I spent a solid 40 minutes or so trying to find a similar issue reported but absolutely nothing returned on it. Only the exact opposite; issues with the scans taking too long to complete.

Anyhow, we can't be the only two with this exact issue all of a sudden.
I'm going to give the Defender Offline scan another shot and see if will actually scan and return a result this time. I've done the Offline scan before and it took around 10-15 minutes iirc and also gave me a prompt/window showing that it completed. Now, it just reboots my pc and I get no notification, window or prompt about the scan and checking the "Protection history" shows 0 results.

This is just odd behavior all of a sudden...
 
Sep 18, 2019
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Ok, my Tamper Protection was oddly disabled for whatever reason...

Yeah, prior to posting here, I spent a solid 40 minutes or so trying to find a similar issue reported but absolutely nothing returned on it. Only the exact opposite; issues with the scans taking too long to complete.

Anyhow, we can't be the only two with this exact issue all of a sudden.
I'm going to give the Defender Offline scan another shot and see if will actually scan and return a result this time. I've done the Offline scan before and it took around 10-15 minutes iirc and also gave me a prompt/window showing that it completed. Now, it just reboots my pc and I get no notification, window or prompt about the scan and checking the "Protection history" shows 0 results.

This is just odd behavior all of a sudden...
I tried to restart my PC and do the scan again... same "problem", only 7 seconds with 48 files scanned, be it Quick or Full Scan.

Well, Malwarebytes quick scan is also quite fast... I wonder if this is now a improvement on Windows Defender, instead of a defect. We can say that Microsoft knows everything about the Windows... if MB can do a so quick scan, maybe WD can also do. Maybe in some way the files are all scanned in the background, so there is no need to scan them manually again.

Well... let's see if more persons come here to tell us more about it.
 
Sep 18, 2019
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Interesting your MB scan is now much faster too. My MB scan time remained unchanged; about 30 seconds as always.

Made a third attempt to do a Defender Offline scan and this time it took around 10 minutes and showed it was actually scanning, or at least appearing to... I say that because after the reboot, I didn't receive a window or prompt showing me results and once again, Protection History showed nothing was done.

I agree on the wait and see if others are experiencing this too. Hopefully, we'll see if it's been acknowledged by MS and get an explanation.
 
Sep 18, 2019
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Interesting your MB scan is now much faster too. My MB scan time remained unchanged; about 30 seconds as always.

Made a third attempt to do a Defender Offline scan and this time it took around 10 minutes and showed it was actually scanning, or at least appearing to... I say that because after the reboot, I didn't receive a window or prompt showing me results and once again, Protection History showed nothing was done.

I agree on the wait and see if others are experiencing this too. Hopefully, we'll see if it's been acknowledged by MS and get an explanation.
It was my Malwarebytes Quick scan that is quite fast... about 8 seconds. It was always like that... The full scan of my Malwarebytes is something like 7 or 8 minutes.

My Windows Defender full scan took now 21 seconds and scanned the 48 files that the Quick scan also scanned.

The Windows Defender Quick scan last 7 seconds now.

Sorry, English is not my first language... so sometimes I can do a bit of confusion.
 
Sep 18, 2019
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No worries, would never have guessed it wasn't your first language. Anyhow, you prompted me to check if I've been running a full scan all along in MB and I noticed that scanning for rootkits was disabled. Enabled it and did another scan and it adds an extra 30 seconds which isn't too bad. Just glad it didn't find anything.
 
Sep 18, 2019
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No worries, would never have guessed it wasn't your first language. Anyhow, you prompted me to check if I've been running a full scan all along in MB and I noticed that scanning for rootkits was disabled. Enabled it and did another scan and it adds an extra 30 seconds which isn't too bad. Just glad it didn't find anything.
I think its a improvement in Windows 10 and in Windows Defender... not a virus, not any malware... I think Microsoft did something in these last updates.
 

Ralston18

Titan
Moderator
Hmm...my own rig (which just did a Windows update a few hours ago) also only scanned 29 files in the Defender Quick Scan option...

Not sure if that is due to the addition of some very advanced whitelisting (possibly excluding several hundred thousand files known to be unchanged, perhaps?), or what happened or what changes occurred, but...at least we all now know it's not malware. :)
 
Sep 18, 2019
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Hmm...my own rig (which just did a Windows update a few hours ago) also only scanned 29 files in the Defender Quick Scan option...

Not sure if that is due to the addition of some very advanced whitelisting (possibly excluding several hundred thousand files known to be unchanged, perhaps?), or what happened or what changes occurred, but...at least we all now know it's not malware. :)
I think Windows 10 is becoming so light and advanced that hours or even minutes of scan of it's own antivirus is no longer necessary.
 
Sep 18, 2019
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Was your "Tamper Protection" disabled by any chance? Windows Security>Virus & Threat protection>Virus & Threat protection settings>Manage settings. Should be the fourth one down.
I am seeing the same behavior on two win10 systems, one Home, one Pro. Quick Scan only did 47/48 files in 8/9 seconds, respectively. Tamper Protection for both systems is still On. Both just updated Adobe Flash too. Coincidence? I think just yesterday, or the day before, Quick Scans checked over thousands of files. It would vary. Sometimes 27,000, sometimes over 100,000, on the same system. Took minutes, not seconds.

A google brought me here, too, after I noticed this a.m. that my daily scheduled scans on both systems only took a few seconds. Ran Malwarebytes on both. Clean. Ran Quick Scans again, manually, and tooks seconds. Running custom scans on C: now. Seem to be working.

First C: scan finished. About 800,000 files, 14 minutes (3.2GHz quad core Xeon with an SSD). Slower system still scanning. Just noticed. Quick Scans seem to just use one thread, but this Custom scan used all 8.

Edit: Slow system C: scan finished. Almost 800k files, 21 minutes. Again, no threats found.
 
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Sep 18, 2019
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Just out of curiosity I checked my Windows Defender/Quick Scan.
Tamper Protection was off.
Ran Quick Scan - 18,181 files in 42 seconds.
Turned Tamper Protection on - no other changes:
Ran Quick Scan - 19,136 files in 41 seconds.
You may be interested in the following Microsoft link:
https://docs.microsoft.com/en-us/windows/security/threat-protection/microsoft-defender-atp/microsoft-defender-advanced-threat-protection
Are you running the latest updates? I am getting truncated Quick Scans with the latest 9/10/2019 Quality updates (cum Win10, cum .NET, and security Adobe Flash) and 9/18/2019 Definition updates for Defender.

Microsoft Windows [Version 10.0.18362.356] on both Home and Pro. Your link is interesting, but I don't think it applies to either of my systems. I'm not running Enterprise.
 
I'm sure my quick scan of only a one or two days ago did hundreds of thousands of files...

WIndows updated 12 hours ago, now it only finds 23 files worthy of scanning...; it's entirely possible MS is only scanning changed files in critical areas, rather than all of them if they have not been changed...(in which case that might be a very wise move. Let's not assume it is broken, it might just be 'different', and (oddly enough for MS!) .....<gulp> drastically imp[roved? :)

I can find no google searches/youtube complaints of this yet, although I did post of it on Microsoft's automated virtual expert thingies...
 
Sep 18, 2019
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After a couple more security signature updates, both quick and full scans still take only 5 seconds with only 43 files scanned. Prior to last night, a quick scan always scanned either 13k or 23k files (my memory is failing me here) and always took around a minute or so. A full scan taking much longer.

For whatever reason, Windows Defender has determined that my system only has 43 files worth its consideration. I have little experience regarding such matters and am just alleviated that it wasn't just me. It just threw me for a loop. Also having Tamper Protection suddenly disabled on my end without my doing didn't help matters...

It'll be interesting to see what the rhyme and reason is for the quite drastic change in scanning all of a sudden.
 

britechguy

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Jul 2, 2019
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I am on Version 1903, Build 18362.356, Windows 10 Pro.

My last quick scan, as of the moment was on 9/17/2019 at 9:08PM and is stated as having taken 20 minutes and 2 seconds, covering 32888 files.

I'm kicking off another quick scan and will report back on it and whether the time or files scanned is significantly different.

Personally, I'm hoping that they're making Quick Scan function similarly to File History, in that an index of files that have been scanned, with the date-time stamps and file sizes for each and last scan time for each, are kept between quick scans. There is no point in scanning the same files again and again and again if they remain unchanged since the last time they were scanned.
 
Sep 18, 2019
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After a couple more security signature updates, both quick and full scans still take only 5 seconds with only 43 files scanned.
To clarify, I get about the same for Quick and Full scans. I had to run Custom scans, choosing my C: drives, to get the ~800k files, 14/21 minute results I posted above.

Windows and App are on C: (SSD). I seldom(never?) scan my D: (big, slow HDD) drives. I got into the habit of running Custom scans on C: because a Full scan did all drives.

Maybe this is an optimization. It'd be nice. Makes sense, too, if I file hasn't changed, why bother scanning it. Sort of like incremental file system backups. I don't know if this is a valid optimization when it comes to security protocols?
 
Sep 18, 2019
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To clarify, I get about the same for Quick and Full scans. I had to run Custom scans, choosing my C: drives, to get the ~800k files, 14/21 minute results I posted above.

Windows and App are on C: (SSD). I seldom(never?) scan my D: (big, slow HDD) drives. I got into the habit of running Custom scans on C: because a Full scan did all drives.

Maybe this is an optimization. It'd be nice. Makes sense, too, if I file hasn't changed, why bother scanning it. Sort of like incremental file system backups. I don't know if this is a valid optimization when it comes to security protocols?
I also have 2 HDDs of 1TB each one and it's like the Full Scan didn't even bother to scan them. Another strange thing to me. Both are with 600GB of free space.

And now I see that my Malwarebytes full scan took 1 minute and 39 seconds... I said before it take more or less 7 minutes but now is just one to two minutes.

I hope this is really a good thing to us... I don't want to install another antivirus or malware protection because the scans are too fast in the ones I use now.
 

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