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 Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2020-12-21
• Author: Michael Haag, Splunk
• ID: 809b31d2-5462-11eb-ae93-0242ac130002

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

| 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="*recoveryenabled*" (Processes.process="* no*") 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)` 
| `bcdedit_failure_recovery_modification_filter`

Macros

The SPL above uses the following Macros:

• security_content_ctime
• security_content_summariesonly

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.

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

How To Implement

You must be ingesting endpoint data that tracks process activity, including parent-child relationships from your endpoints to populate the Endpoint data model in the Processes node. Tune based on parent process names.

Known False Positives

Administrators may modify the boot configuration.

Associated Analytic Story

• Ryuk Ransomware
• Ransomware

RBA

Risk Score	Impact	Confidence	Message
80.0	100	80	An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ 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

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