Elastic Security Detection Rules

Rare SMB Connection to the Internet

Last updated 5 months ago on 2025-03-20
Created 2 years ago on 2023-12-04

About

This rule detects rare internet network connections via the SMB protocol. SMB is commonly used to leak NTLM credentials via rogue UNC path injection.
Tags
Domain: EndpointOS: WindowsUse Case: Threat DetectionTactic: ExfiltrationData Source: Elastic EndgameData Source: Elastic DefendData Source: Microsoft Defender for EndpointData Source: SysmonData Source: SentinelOneLanguage: kuery
Severity
medium
Risk Score
47
MITRE ATT&CK™

Exfiltration (TA0010)(opens in a new tab or window)

↳ Exfiltration Over Alternative Protocol (T1048)(opens in a new tab or window)

License
Elastic License v2(opens in a new tab or window)

Definition

Rule Type
New Terms Rule
Integration Pack
Prebuilt Security Detection Rules
Index Patterns
logs-endpoint.events.network-*winlogbeat-*logs-windows.sysmon_operational-*endgame-*logs-m365_defender.event-*logs-sentinel_one_cloud_funnel.*
Related Integrations

endpoint(opens in a new tab or window)

windows(opens in a new tab or window)

m365_defender(opens in a new tab or window)

sentinel_one_cloud_funnel(opens in a new tab or window)

Query
event.category:network and host.os.type:windows and process.pid:4 and
  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
    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"
  )

Install detection rules in Elastic Security

Detect Rare SMB Connection to the Internet in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(opens in a new tab or window).