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splunk-security_content/dev/endpoint/prevent_automatic_repair_mode_using_bcdedit.yml
2023-01-20 13:24:15 +01:00

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YAML

name: Prevent Automatic Repair Mode using Bcdedit
id: 7742aa92-c9d9-11eb-bbfc-acde48001122
version: 1
date: '2021-06-10'
author: Teoderick Contreras, Splunk
status: production
type: TTP
description: This search is to detect a suspicious bcdedit.exe execution to ignore
all failures. This technique was used by ransomware to prevent the compromise machine
automatically boot in repair mode.
data_source:
- Sysmon Event ID 1
search:
selection1:
CommandLine: '*bootstatuspolicy*'
Image|endswith: bcdedit.exe
selection2:
CommandLine: '*ignoreallfailures*'
condition: selection1 and selection2
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 bcdedit.exe may be used.
known_false_positives: Administrators may modify the boot configuration ignore failure
during testing and debugging.
references:
- https://jsac.jpcert.or.jp/archive/2020/pdf/JSAC2020_1_tamada-yamazaki-nakatsuru_en.pdf
tags:
analytic_story:
- Ransomware
asset_type: Endpoint
confidence: 80
impact: 70
message: A suspicious process $process_name$ with process id $process_id$ contains
commandline $process$ to ignore all bcdedit execution failure in host $dest$
mitre_attack_id:
- T1490
observable:
- name: dest
type: Hostname
role:
- Victim
- name: user
type: User
role:
- Victim
product:
- Splunk Enterprise
- Splunk Enterprise Security
- Splunk Cloud
risk_score: 56
security_domain: endpoint
tests:
- name: True Positive Test
attack_data:
- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/malware/ransomware_ttp/data1/windows-sysmon.log
source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
sourcetype: xmlwineventlog