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Elastic Docs ›Elastic Security Solution [7.16] ›Detections and alerts ›Prebuilt rule reference

SMB (Windows File Sharing) Activity to the Internet

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SMB (Windows File Sharing) Activity to the Internet

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This rule detects network events that may indicate the use of Windows file sharing (also called SMB or CIFS) traffic to the Internet. SMB is commonly used within networks to share files, printers, and other system resources amongst trusted systems. It should almost never be directly exposed to the Internet, as it is frequently targeted and exploited by threat actors as an initial access or backdoor vector or for data exfiltration.

Rule type: query

Rule indices:

  • auditbeat-*
  • filebeat-*
  • packetbeat-*
  • logs-endpoint.events.*

Severity: high

Risk score: 73

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Host
  • Network
  • Threat Detection
  • Initial Access
  • Host

Version: 11 (version history)

Added (Elastic Stack release): 7.6.0

Last modified (Elastic Stack release): 7.15.0

Rule authors: Elastic

Rule license: Elastic License v2

Rule query

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

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 11 (7.15.0 release)
  • Formatting only
Version 10 (7.14.0 release)

  • Updated query, changed from:

    event.category:(network or network_traffic) and network.transport:tcp
and (destination.port:(139 or 445) or event.dataset:zeek.smb) and
source.ip:( 10.0.0.0/8 or 172.16.0.0/12 or 192.168.0.0/16 ) and not
destination.ip:( 10.0.0.0/8 or 127.0.0.0/8 or 169.254.0.0/16 or
172.16.0.0/12 or 192.168.0.0/16 or 224.0.0.0/4 or "::1" or "FE80::/10"
or "FF00::/8" )
Version 8 (7.12.0 release)
  • Formatting only
Version 7 (7.11.2 release)
  • Formatting only
Version 6 (7.11.0 release)

  • Updated query, changed from:

    event.category:(network or network_traffic) and network.transport:tcp
and (destination.port:(139 or 445) or event.dataset:zeek.smb) and
source.ip:(10.0.0.0/8 or 172.16.0.0/12 or 192.168.0.0/16) and not
destination.ip:(10.0.0.0/8 or 127.0.0.0/8 or 172.16.0.0/12 or
192.168.0.0/16 or "::1")
Version 5 (7.10.0 release)
  • Formatting only
Version 4 (7.9.0 release)

  • Updated query, changed from:

    network.transport:tcp and destination.port:(139 or 445) and
source.ip:(10.0.0.0/8 or 172.16.0.0/12 or 192.168.0.0/16) and not
destination.ip:(10.0.0.0/8 or 127.0.0.0/8 or 172.16.0.0/12 or
192.168.0.0/16 or "::1")
Version 3 (7.7.0 release)

  • Updated query, changed from:

    network.transport: tcp and destination.port: (139 or 445) and (
network.direction: outbound or ( source.ip: (10.0.0.0/8 or
172.16.0.0/12 or 192.168.0.0/16) and not destination.ip: (10.0.0.0/8
or 172.16.0.0/12 or 192.168.0.0/16) ) )
Version 2 (7.6.1 release)
  • Removed auditbeat-*, packetbeat-*, and winlogbeat-* from the rule indices.
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