Question Question on a Strange Antivirus app behaviour

[krakadoros]

I have on my Desktop an .exe file.
Copy this file and past on Desktop.

Now i have two .exe files (same, except their names).

1. Right click the first one and scan with my antivirus.
Result >> Antivirus find virus and remove the .exe file.
Now i have only one .exe file (the second).

2.Using a software and extract the second .exe file in a Folder on Desktop.
Now i have the second .exe file and a Folder with the extracted files from the second .exe file.

3.Right click the second .exe file and scan with my antivirus.
Result >> Antivirus find virus and remove the .exe file.

4. Right click the Folder with the extracted files from the second .exe file.
Result >> Antivirus find nothing.

Question :

Is the Folder with the extracted files from the second .exe file, save to use, ie to click on
the setup.exe file (inside the Folder), to execute the installation ?

Thanks.

my system
Win10 32bit

 

[rgd1101]

what anti virus do you have? it is up to date?

 

[krakadoros]

Thanks for reply.
Windows Defender. And yes it is updated.
But the question is how comes and the first time (when the .exe file is not extracted), the virus detected, and the second time (when the exe. file is extracted in a Folder), the virus do not detected.
I think this is not have to do with if the Antivirus is updated or not. If it was not updated, then the first time the virus have not been detected and removed.
If there is another virus (except the one that have been detected) inside the .exe file, and did not detected, this could be a subject of update but this is a different case.
Here we have one detection only.
The only thing i can think is that the Extractor application, remove the virus, during the extraction. So i made an experiment. I create a virus. Put it in a zip folder (i compressed it) and then i extract it in a folder. Then try my Antivirus to check both. The virus file and the folder with the extracted virus inside of it.
Results :
Antivirus found and remove the virus in both cases (the virus alone and the virus inside the folder with the extracted virus).
So it seems that my though about the Extractor app removing Virus during the extract processes it is not truth.
So what else can it be ???
Can i safely click on setup.exe in the folder where the original .exe file were extracted ?

 

[rgd1101]

could be a bug. contact microsoft

 

[krakadoros]

Unfortunately it was a bug. And say unfortunately because i deside to install with the .exe file inside the Folder, and it prooved to be a real virus, and very dangerous. It delete some of my files.
I recover the files, thanks to backups i have made.
The conclusion is that the Antivirus software mistakenly though there was no virus in the extracted Folder.
Anyway thanks for your interest.

 

[rgd1101]

could be something new that it not pickup by signature