Detection rules › Sigma

Potential Ransomware or Unauthorized MBR Tampering Via Bcdedit.EXE

Status
test
Severity
medium
Log source
category process_creation, product windows
Author
@neu5ron
Source
github.com/SigmaHQ/sigma

Detects potential malicious and unauthorized usage of bcdedit.exe

MITRE ATT&CK coverage

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 1: Process creation

Rule body

title: Potential Ransomware or Unauthorized MBR Tampering Via Bcdedit.EXE
id: c9fbe8e9-119d-40a6-9b59-dd58a5d84429
status: test
description: Detects potential malicious and unauthorized usage of bcdedit.exe
references:
    - https://learn.microsoft.com/en-us/windows-hardware/drivers/devtest/bcdedit--set
    - https://twitter.com/malwrhunterteam/status/1372536434125512712/photo/2
author: '@neu5ron'
date: 2019-02-07
modified: 2023-02-15
tags:
    - attack.stealth
    - attack.t1070
    - attack.persistence
    - attack.t1542.003
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\bcdedit.exe'
        - OriginalFileName: 'bcdedit.exe'
    selection_cli:
        CommandLine|contains:
            - 'delete'
            - 'deletevalue'
            - 'import'
            - 'safeboot'
            - 'network'
    condition: all of selection_*
level: medium

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_img

selection_img:
    - Image|endswith: '\bcdedit.exe'
    - OriginalFileName: 'bcdedit.exe'

Stage 2: selection_cli

selection_cli:
    CommandLine|contains:
        - 'delete'
        - 'deletevalue'
        - 'import'
        - 'safeboot'
        - 'network'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
CommandLinematch
  • delete corpus 31 (sigma 16, elastic 8, splunk 6, kusto 1)
  • deletevalue corpus 2 (sigma 2)
  • import corpus 4 (sigma 4)
  • network corpus 3 (sigma 2, splunk 1)
  • safeboot corpus 3 (splunk 2, sigma 1)
field:"CommandLine" kind:match
Imageends_with
  • \bcdedit.exe corpus 5 (sigma 5)
field:"Image" kind:ends_with value:"\bcdedit.exe"
OriginalFileNameeq
  • bcdedit.exe corpus 13 (elastic 11, sigma 2)
field:"OriginalFileName" kind:eq value:"bcdedit.exe"