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Description

This search is to detect a suspicious bcdedit commandline to configure the host to boot in safe mode with network config. This technique was seen in blackMatter ransomware where it force the compromised host to boot in safe mode to continue its encryption and bring back to normal boot using bcdedit deletevalue command. This TTP can be a good alert for host that booted from safe mode forcefully since it need to modify the boot configuration to bring it back to normal.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-09-06
  • Author: Teoderick Contreras, Splunk
  • ID: 81f1dce0-0f18-11ec-a5d7-acde48001122

ATT&CK

ID Technique Tactic
T1490 Inhibit System Recovery Impact

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name = bcdedit.exe Processes.process="*/set*" Processes.process="*{current}*"  Processes.process="*safeboot*" Processes.process="*network*" by Processes.process_name Processes.process Processes.parent_process_name Processes.dest Processes.user 
|`drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `change_to_safe_mode_with_network_config_filter`

Associated Analytic Story

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. Tune and filter known instances where renamed rundll32.exe may be used.

Required field

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

Kill Chain Phase

  • Exploitation

Known False Positives

unknown

RBA

Risk Score Impact Confidence Message
25.0 50 50 bcdedit process with commandline $process$ to force safemode boot the $dest$

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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