I had the same issue - searching across the Endpoint.Filesystem dataset would return the file_hash field with the value unknown. I noticed that the calculated field (source::XmlWinEventLog:Microsoft-Windows-Sysmon/Operational : EVAL-file_hash) = case( EventCode IN ("15"), Hash, EventCode IN ("23","26"), Hashes ), and the event type for ms-sysmon-filemod = (source="WinEventLog:Microsoft-Windows-Sysmon/Operational" OR source="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational") (EventCode IN ("2","11","23","26") ). I modified the ms-sysmon-filemod to = (source="WinEventLog:Microsoft-Windows-Sysmon/Operational" OR source="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational") (EventCode IN ("2","11", "15","23","26") ) For some reason Event Code 15 was showing in the event type ms-sysmon-process = (source="WinEventLog:Microsoft-Windows-Sysmon/Operational" OR source="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational") (EventCode IN ("1","5","6","7","8","9","10", "15","17","18","24","25") )
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