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Detection rules › Sigma

Suspicious Reg Add BitLocker

Status
test
Severity
high
Log source
product windows, category process_creation
Author
frack113
Source
github.com/SigmaHQ/sigma

Detects suspicious addition to BitLocker related registry keys via the reg.exe utility

MITRE ATT&CK coverage

TacticTechniques
ImpactT1486 Data Encrypted for Impact

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation
Security-AuditingEvent ID 4688A new process has been created.

Rule body yaml

title: Suspicious Reg Add BitLocker
id: 0e0255bf-2548-47b8-9582-c0955c9283f5
status: test
description: Detects suspicious addition to BitLocker related registry keys via the reg.exe utility
references:
    - https://thedfirreport.com/2021/11/15/exchange-exploit-leads-to-domain-wide-ransomware/
author: frack113
date: 2021-11-15
modified: 2022-09-09
tags:
    - attack.impact
    - attack.t1486
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        CommandLine|contains|all:
            - 'REG'
            - 'ADD'
            - '\SOFTWARE\Policies\Microsoft\FVE'
            - '/v'
            - '/f'
        CommandLine|contains:
            - 'EnableBDEWithNoTPM'
            - 'UseAdvancedStartup'
            - 'UseTPM'
            - 'UseTPMKey'
            - 'UseTPMKeyPIN'
            - 'RecoveryKeyMessageSource'
            - 'UseTPMPIN'
            - 'RecoveryKeyMessage'
    condition: selection
falsepositives:
    - Unlikely
level: high

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    CommandLine|contains|all:
        - 'REG'
        - 'ADD'
        - '\SOFTWARE\Policies\Microsoft\FVE'
        - '/v'
        - '/f'
    CommandLine|contains:
        - 'EnableBDEWithNoTPM'
        - 'UseAdvancedStartup'
        - 'UseTPM'
        - 'UseTPMKey'
        - 'UseTPMKeyPIN'
        - 'RecoveryKeyMessageSource'
        - 'UseTPMPIN'
        - 'RecoveryKeyMessage'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
CommandLinematch
  • /f corpus 7 (sigma 5, splunk 1, kusto 1)
  • /v corpus 5 (sigma 4, kusto 1)
  • ADD corpus 34 (sigma 26, splunk 4, chronicle 2, kusto 2)
  • EnableBDEWithNoTPM corpus 3 (sigma 2, kusto 1)
  • REG corpus 7 (sigma 5, splunk 1, kusto 1)
  • RecoveryKeyMessage corpus 3 (sigma 2, kusto 1)
  • RecoveryKeyMessageSource corpus 3 (sigma 2, kusto 1)
  • UseAdvancedStartup corpus 3 (sigma 2, kusto 1)
  • UseTPM corpus 2 (sigma 2)
  • UseTPMKey corpus 3 (sigma 2, kusto 1)
  • UseTPMKeyPIN corpus 3 (sigma 2, kusto 1)
  • UseTPMPIN corpus 2 (sigma 2)
  • \SOFTWARE\Policies\Microsoft\FVE corpus 2 (sigma 2)