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<p class="MsoNormal">For the “SMB::FILE OPEN” action, I believe you would see this action when viewing a network shared folder. The SMB::FILE OPEN action applies to both files and directories, and I believe there is a flag in one of the SMB headers that specifies
if it is a folder.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">For the “extracted files” issue, that sounds strange, but if the files appear in the “extracted” folder, then those executables are being transferred across the wire. I don’t think Zeek could collect those files otherwise. The only thing
I can think of at the moment is that Microsoft Windows has a feature called AutoRun or AutoPlay. Best practice is to disable it, but if it is enabled on your Windows machines, then perhaps it could explain the behavior.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Microsoft article on how to disable AutoRun/AutoPlay:<o:p></o:p></p>
<p class="MsoNormal">https://docs.microsoft.com/en-us/windows/win32/shell/autoplay-reg<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="color:#0033CC">Mark<o:p></o:p></span></p>
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<p class="MsoNormal"><b>From:</b> zeek-bounces@zeek.org <zeek-bounces@zeek.org> <b>
On Behalf Of </b>security devops<br>
<b>Sent:</b> Tuesday, June 16, 2020 4:28 AM<br>
<b>To:</b> zeek@zeek.org<br>
<b>Subject:</b> [EXT] [Zeek] Question on Zeek SMB Logs and action "SMB::FILE OPEN"<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Helvetica",sans-serif">Hi</span><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Helvetica",sans-serif">I'm running Security Onion with Zeek 3.0.7.</span><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Helvetica",sans-serif">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.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Helvetica",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Helvetica",sans-serif">There would be an action of "SMB::FILE OPEN" for all these executables and it would be extracted to the "nsm/bro/extracted" folder.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Helvetica",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Helvetica",sans-serif">Is this the default behaviour as it seems odd that the files are extracted even though they did not cross the wire?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Helvetica",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Helvetica",sans-serif">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?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Helvetica",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Helvetica",sans-serif">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).<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Helvetica",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Helvetica",sans-serif">thank you<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt;font-family:"Helvetica",sans-serif"><o:p> </o:p></span></p>
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