Elastic high stable kql

SMB (Windows File Sharing) Activity from the Internet

This rule detects network events that may indicate inbound Windows file sharing (SMB or CIFS) traffic originating from the Internet. SMB should never be directly reachable from the Internet, as it is a primary target for exploitation by threat actors seeking initial access. Inbound SMB from a public IP is a direct precondition for attacks such as EternalBlue (MS17-010) and related SMB remote code execution vulnerabilities.

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Detection Logic

(data_stream.dataset:(fortinet_fortigate.log or network_traffic.flow or pfsense.log or zeek.smb_cmd or zeek.smb_files or zeek.smb_mapping) or event.category:(network or network_traffic))
  and network.transport:tcp and destination.port:(139 or 445)
  and destination.ip:(10.0.0.0/8 or 172.16.0.0/12 or 192.168.0.0/16)
  and not source.ip:(
    10.0.0.0/8
    or 100.64.0.0/10
    or 127.0.0.0/8
    or 169.254.0.0/16
    or 172.16.0.0/12
    or 192.0.0.0/24
    or 192.0.0.0/29
    or 192.0.0.10/32
    or 192.0.0.170/32
    or 192.0.0.171/32
    or 192.0.0.8/32
    or 192.0.0.9/32
    or 192.0.2.0/24
    or 192.168.0.0/16
    or 192.175.48.0/24
    or 192.31.196.0/24
    or 192.52.193.0/24
    or 192.88.99.0/24
    or 198.18.0.0/15
    or 198.51.100.0/24
    or 203.0.113.0/24
    or 224.0.0.0/4
    or 240.0.0.0/4
    or "::1"
    or "FE80::/10"
    or "FF00::/8"
  )

Field Validations

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