IMPORTANT: No additional bug fixes or documentation updates will be released for this version. For the latest information, see the current release documentation.

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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:

packetbeat-*
auditbeat-*
filebeat-*
logs-network_traffic.*

Severity: high

Risk score: 73

Runs every: 5m

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

Maximum alerts per execution: 100

References:

https://www.iana.org/assignments/iana-ipv4-special-registry/iana-ipv4-special-registry.xhtml

Tags:

Tactic: Initial Access
Domain: Endpoint
Use Case: Threat Detection

Version: 103

Rule authors:

Elastic

Rule license: Elastic License v2

Rule query

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(event.dataset: network_traffic.flow or (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"
  )

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Initial Access
- ID: TA0001
- Reference URL: https://attack.mitre.org/tactics/TA0001/
Technique:
- Name: Exploit Public-Facing Application
- ID: T1190
- Reference URL: https://attack.mitre.org/techniques/T1190/
Tactic:
- Name: Exfiltration
- ID: TA0010
- Reference URL: https://attack.mitre.org/tactics/TA0010/
Technique:
- Name: Exfiltration Over Alternative Protocol
- ID: T1048
- Reference URL: https://attack.mitre.org/techniques/T1048/

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