Direct Outbound SMB Connection

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Identifies unexpected processes making network connections over port 445. Windows File Sharing is typically implemented over Server Message Block (SMB), which communicates between hosts using port 445. When legitimate, these network connections are established by the kernel. Processes making 445/tcp connections may be port scanners, exploits, or suspicious user-level processes moving laterally.

Rule type: eql

Rule indices:

  • winlogbeat-*
  • logs-endpoint.events.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

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

Maximum alerts per execution: 100

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Lateral Movement

Version: 5 (version history)

Added (Elastic Stack release): 7.6.0

Last modified (Elastic Stack release): 7.10.0

Rule authors: Elastic

Rule license: Elastic License

Rule query

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sequence by process.entity_id [process where event.type == "start"
and process.pid != 4] [network where destination.port == 445 and
process.pid != 4 and not cidrmatch(destination.ip, "127.0.0.1",
"::1")]

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 5 (7.10.0 release)
  • Updated query, changed from:

    event.category:network and event.type:connection and
    destination.port:445 and not process.pid:4 and not
    destination.ip:(127.0.0.1 or "::1")
Version 4 (7.9.1 release)
  • Formatting only
Version 3 (7.9.0 release)
  • Updated query, changed from:

    event.action:"Network connection detected (rule: NetworkConnect)" and
    destination.port:445 and not process.pid:4 and not
    destination.ip:(127.0.0.1 or "::1")
Version 2 (7.7.0 release)
  • Updated query, changed from:

    event.action:"Network connection detected (rule: NetworkConnect)" and
    destination.port:445 and not process.pid:4 and not
    destination.ip:("127.0.0.1" or "::1")