⚠️ WARNING THIS IS A EXPERIMENTAL DETECTION

We have not been able to test, simulate or build datasets for it, use at your own risk!

Try in Splunk Security Cloud

Description

This search looks for spikes in the number of Server Message Block (SMB) traffic connections.

  • Type: Anomaly
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Network_Traffic
  • Last Updated: 2020-07-22
  • Author: David Dorsey, Splunk
  • ID: 7f5fb3e1-4209-4914-90db-0ec21b936378

ATT&CK

ID Technique Tactic
T1021.002 SMB/Windows Admin Shares Lateral Movement
T1021 Remote Services Lateral Movement

| tstats `security_content_summariesonly` count from datamodel=Network_Traffic where All_Traffic.dest_port=139 OR All_Traffic.dest_port=445 OR All_Traffic.app=smb by _time span=1h, All_Traffic.src 
| `drop_dm_object_name("All_Traffic")` 
| eventstats max(_time) as maxtime 
| stats count as num_data_samples max(eval(if(_time >= relative_time(maxtime, "-70m@m"), count, null))) as count avg(eval(if(_time<relative_time(maxtime, "-70m@m"), count, null))) as avg stdev(eval(if(_time<relative_time(maxtime, "-70m@m"), count, null))) as stdev by src 
| eval upperBound=(avg+stdev*2), isOutlier=if(count > upperBound AND num_data_samples >=50, 1, 0) 
| where isOutlier=1 
| table src count 
| `smb_traffic_spike_filter` 

Associated Analytic Story

How To Implement

This search requires you to be ingesting your network traffic logs and populating the Network_Traffic data model.

Required field

  • _time
  • All_Traffic.dest_port
  • All_Traffic.app
  • All_Traffic.src

Kill Chain Phase

  • Actions on Objectives

Known False Positives

A file server may experience high-demand loads that could cause this analytic to trigger.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

source | version: 3