BCDEdit Failure Recovery Modification

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Description

This search looks for flags passed to bcdedit.exe modifications to the built-in Windows error recovery boot configurations. This is typically used by ransomware to prevent recovery.

• Type: TTP

• Product: Splunk Behavioral Analytics

• Last Updated: 2021-12-07
• Author: Michael Haag, Splunk
• ID: 76d79d6e-25bb-40f6-b3b2-e0a6b7e5ea13

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1490	Inhibit System Recovery	Impact

Kill Chain Phase

• Actions On Objectives

NIST

• DE.CM

CIS20

• CIS 10

CVE

Search

 $main = from source  
| eval timestamp = time  
| eval metadata_uid = metadata.uid  
| eval process_pid = process.pid 
| eval process_file = process.file 
| eval process_file_path = process_file.path 
| eval process_file_name = lower(process_file.name) 
| eval process_cmd_line = process.cmd_line 
| eval actor_user = actor.user 
| eval actor_user_name = actor_user.name 
| eval actor_process = actor.process 
| eval actor_process_pid = actor_process.pid 
| eval actor_process_file = actor_process.file 
| eval actor_process_file_path = actor_process_file.path 
| eval actor_process_file_name = actor_process_file.name 
| eval device_hostname = device.hostname 
| where process_file_name="bcdedit.exe" AND (process_cmd_line LIKE "%no%" AND process_cmd_line LIKE "%recoveryenabled%") --finding_report--

Macros

The SPL above uses the following Macros:

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

Required fields

List of fields required to use this analytic.

• process.pid
• process.file.path
• process.file.name
• process.cmd_line
• actor.user.name
• actor.process.pid
• actor.process.file.path
• actor.process.file.name
• device.hostname

How To Implement

To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the Endpoint_Processess datamodel.

Known False Positives

Administrators may modify the boot configuration.

Associated Analytic Story

• Ryuk Ransomware
• Ransomware
• Information Sabotage

RBA

Risk Score	Impact	Confidence	Message
80.0	100	80	An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest_device_id$ by user $dest_user_id$ attempting disable the ability to recover the endpoint.

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

• https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1490/T1490.md#atomic-test-4—windows—disable-windows-recovery-console-repair

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: 4