Malwarebytes false negative?

[hamguy]

Windows 10 defender is reporting an exe file, has the Azden.B!cl virus, but Malwarebytes says the file is ok. How can I determine which is correct?

I am using Malwarebytes Premium 4.1.2 with all updates.

Thanks!

[Malwarebytes]

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[Porthos]

11 minutes ago, hamguy said:

but Malwarebytes says the file is ok. How can I determine which is correct?

There are items that Defender detects that Malwarebytes does not.

Malwarebytes does not target script files during a scan.. That means MB will not target; JS, HTML, VBS, .CLASS, SWF, BAT, CMD, PDF, PHP, etc.

It also does not target documents such as; PDF, DOC, DOCx, XLS, XLSx, PPT, PPS, ODF, etc.

It also does not target media files;  MP3, WMV, JPG, GIF, etc.

Malwarebytes will detect files like these on execution only.

What type of file is it?

[hamguy]

It is an ".exe" file - the newest version of VARA for digital HAM radio that all HAM radio operators in the world MUST update to by tomorrow, and only has been available in the last day or two. Hmmm, sounds like a made-for-hackers moment to me, so I didn't just bypass the warning and trust Malwarebytes. Just an hour ago, the creators of VARA verified that there is a problem with their ".exe" installation file, and they will be releasing a fix to it some time later today.

So, my question changes - Azden.B!cl is a serious ransomware threat; why did Malwarebytes not detect it? I attached the zip file that I downloaded which contains the new VARA installation file - so that you can inspect the ".exe" file (but don't run it!).

VARA HF v4.0.1 setup (do not install until June 30th)-1.zip

[Porthos]

7 minutes ago, hamguy said:

why did Malwarebytes not detect it?

Creation Time 1992-06-19 22:22:17

https://www.virustotal.com/gui/file/e7618dd48b763bd7dcf60a8d85dbbcc7269ec17b6c8604a68c7321bdc699a60a/detection

The file is too old to be in the MB database.

And it was removed from Microsoft's database in the last 2 hours.  Do a manual update for Defender.

 

[hamguy]

I did a manual update earlier using CMD to "C:\Program Files\Windows Defender>mpcmdrun -SignatureUpdate". I tried that command again, and received a "No updates needed". I rebooted windows 10 and tried running the ".exe" again with the same result. Since the microsoft update is only 2 hours old, it may not have made it around the world to all of their CDN servers. So, I'll try the same thing again tomorrow. Please let me know if it sounds like I am doing things correctly.

[Porthos]

51 minutes ago, hamguy said:

I did a manual update earlier using CMD to "C:\Program Files\Windows Defender>mpcmdrun -SignatureUpdate". I tried that command again, and received a "No updates needed". I rebooted windows 10 and tried running the ".exe" again with the same result. Since the microsoft update is only 2 hours old, it may not have made it around the world to all of their CDN servers. So, I'll try the same thing again tomorrow. Please let me know if it sounds like I am doing things correctly.

I just did a right click on the file you attached and I get no detection from Defender.

[hamguy]

You should unzip the ".exe" file first to a safe place on your local hard drive, then do a right click, then select "Scan with Windows Defender". This is the result I see (shows 3 different scans I have run)

[Porthos]

46 minutes ago, hamguy said:

You should unzip the ".exe" file first to a safe place on your local hard drive, then do a right click, then select "Scan with Windows Defender". This is the result I see (shows 3 different scans I have run)

I did that. ( not my first BBQ)

 

[hamguy]

Ok, I'm puzzled. Must be something wrong with my use of/or version of windows defender. Thank you for checking it out for me.

[Porthos]

Just now, hamguy said:

Must be something wrong with my use of/or version of windows defender

What version of 10 are you on.

[hamguy]

I am running Version 10.0.18363 Build 18363, and have seen advice to NOT update to the latest version of Windows 10 which apparently has serious bugs.

[Porthos]

40 minutes ago, hamguy said:

and have seen advice to NOT update to the latest version of Windows 10 which apparently has serious bugs.

Some have issues and some don't. It is the song and dance every 6 months. I am fully up to date with 2004. Defender seems to get better with every feature upgrade.

I and 62 of my clients run 2004 with no issue. Getting ready to do 63 and 64 tomorrow. I do some serious prep before upgrade and also do an Image of the computer before just in case.