Question on Zeek SMB Logs and action "SMB::FILE OPEN"

Zeek
1

Hi
I’m running Security Onion with Zeek 3.0.7.

I have a client accessing a NAS. Whenever a client accesses a folder containing executables, Zeek will detect a “bro_smb_files” event type for all the executable in the folder, even though the client did not open these executables.

There would be an action of “SMB::FILE OPEN” for all these executables and it would be extracted to the “nsm/bro/extracted” folder.

Is this the default behaviour as it seems odd that the files are extracted even though they did not cross the wire?

I’m also a little confused over “SMB::FILE OPEN” action when I referenced Zeek documentation. Does it mean the file was “open” even though the client only accessed the mapped folder?

The follow up question on this would be forensic integrity of the files. Would this weird SMB behavior affect the “access” date of the file (I am referring to MACB dates of file).

thank you