Suspicious Reg Add BitLocker

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

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

Known false positives

Unlikely

MITRE ATT&CK coverage

Tactic	Techniques
Impact	`T1486` Data Encrypted for Impact

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation
Security-Auditing	Event ID 4688: A new process has been created.

Rule body

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

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`/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)	`field:"CommandLine" kind:match`

Suspicious Reg Add BitLocker

Known false positives

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection

Indicators

Stage 0: `condition`

Stage 1: `selection`