Try in Splunk Security Cloud

Description

This analytic is to detect a suspicious high frequency copying/moving of files in network share as part of information sabotage. This anomaly event can be a good indicator of insider trying to sabotage data by transfering classified or internal files within network share to exfitrate it after or to lure evidence of insider attack to other user. This behavior may catch several noise if network share is a common place for classified or internal document processing.

  • Type: Anomaly
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-11-16
  • Author: Teoderick Contreras, Splunk
  • ID: 40925f12-4709-11ec-bb43-acde48001122

ATT&CK

ID Technique Tactic
T1537 Transfer Data to Cloud Account Exfiltration
`wineventlog_security` EventCode=5145 Relative_Target_Name IN ("*.doc","*.docx","*.xls","*.xlsx","*.ppt","*.pptx","*.log","*.txt","*.db","*.7z","*.zip","*.rar","*.tar","*.gz","*.jpg","*.gif","*.png","*.bmp","*.pdf","*.rtf","*.key") Object_Type=File Share_Name IN ("\\\\*\\C$","\\\\*\\IPC$","\\\\*\\admin$") Access_Mask= "0x2" 
|  bucket _time span=5m 
| stats values(Relative_Target_Name) as valRelativeTargetName, values(Share_Name) as valShareName, values(Object_Type) as valObjectType, values(Access_Mask) as valAccessmask, values(src_port) as valSrcPort, values(Source_Address) as valSrcAddress count as numShareName by dest, _time, EventCode, user 
| eventstats avg(numShareName) as avgShareName, stdev(numShareName) as stdShareName, count as numSlots by dest, _time, EventCode, user 
|  eval upperThreshold=(avgShareName + stdShareName *3) 
|  eval isOutlier=if(avgShareName > 20 and avgShareName >= upperThreshold, 1, 0) 
|  search isOutlier=1 
| `high_frequency_copy_of_files_in_network_share_filter`

Associated Analytic Story

How To Implement

o successfully implement this search, you need to be ingesting Windows Security Event Logs with 5145 EventCode enabled. The Windows TA is also required. Also enable the object Audit access success/failure in your group policy.

Required field

  • _time
  • EventCode
  • Share_Name
  • Relative_Target_Name
  • Object_Type
  • Access_Mask
  • user
  • src_port
  • Source_Address

Kill Chain Phase

  • Exfiltration

Known False Positives

this behavior may seen in normal transfer of file within network if network share is common place for sharing documents.

RBA

Risk Score Impact Confidence Message
9.0 30 30 high frequency copy of document in network share $Share_Name$ from $Source_Address$ by $user$

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: 1