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Description

This search is to detect execution of wevtutil.exe to disable logs. This technique was seen in several ransomware to disable the event logs to evade alerts and detections.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint- Datasource: Splunk Add-on for Sysmon
  • Last Updated: 2021-06-10
  • Author: Teoderick Contreras, Splunk
  • ID: 236e7c8e-c9d9-11eb-a824-acde48001122

Annotations

ATT&CK
ID Technique Tactic
T1070 Indicator Removal on Host Defense Evasion
T1070.001 Clear Windows Event Logs Defense Evasion
Kill Chain Phase
  • Exploitation
NIST
CIS20
CVE
1
2
3
4
5
6
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name = "wevtutil.exe" Processes.process = "*sl*" Processes.process = "*/e:false*" by Processes.parent_process_name Processes.parent_process Processes.process_name Processes.process Processes.dest Processes.user Processes.process_id Processes.process_guid 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `disable_logs_using_wevtutil_filter`

Macros

The SPL above uses the following Macros:

Note that disable_logs_using_wevtutil_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

  • _time
  • Processes.parent_process_name
  • Processes.parent_process
  • Processes.process_name
  • Processes.process
  • Processes.dest
  • Processes.user
  • Processes.process_id
  • Processes.process_guid

How To Implement

To successfully implement this search, you need to be ingesting logs with the process name, parent process, and command-line executions from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.

Known False Positives

network operator may disable audit event logs for debugging purposes.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
24.0 30 80 WevtUtil.exe used to disable Event Logging on $dest

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

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