Add SafeBoot Keys Via Reg Utility

Status: test
Severity: high
Log source: category process_creation, product windows
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects execution of "reg.exe" commands with the "add" or "copy" flags on safe boot registry keys. Often used by attacker to allow the ransomware to work in safe mode as some security products do not

Known false positives

Unlikely

MITRE ATT&CK coverage

Tactic	Techniques
Defense Impairment	`T1685` Disable or Modify Tools

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: Add SafeBoot Keys Via Reg Utility
id: d7662ff6-9e97-4596-a61d-9839e32dee8d
related:
    - id: fc0e89b5-adb0-43c1-b749-c12a10ec37de
      type: similar
status: test
description: Detects execution of "reg.exe" commands with the "add" or "copy" flags on safe boot registry keys. Often used by attacker to allow the ransomware to work in safe mode as some security products do not
references:
    - https://redacted.com/blog/bianlian-ransomware-gang-gives-it-a-go/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2022-09-02
modified: 2024-03-19
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\reg.exe'
        - OriginalFileName: 'reg.exe'
    selection_safeboot:
        CommandLine|contains: '\SYSTEM\CurrentControlSet\Control\SafeBoot'
    selection_flag:
        CommandLine|contains:
            - ' copy '
            - ' add '
    condition: all of selection*
falsepositives:
    - Unlikely
level: high
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_reg_add_safeboot/info.yml

Stages and Predicates

Stage 0: `condition`

all of selection*

Stage 1: `selection_img`

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

Stage 2: `selection_safeboot`

selection_safeboot:
    CommandLine|contains: '\SYSTEM\CurrentControlSet\Control\SafeBoot'

Stage 3: `selection_flag`

selection_flag:
    CommandLine|contains:
        - ' copy '
        - ' add '

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`add` corpus 15 (sigma 13, splunk 1, chronicle 1) `copy` corpus 4 (sigma 4) `\SYSTEM\CurrentControlSet\Control\SafeBoot` corpus 2 (sigma 2)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\reg.exe` corpus 58 (sigma 58)	`field:"Image" kind:ends_with value:"\reg.exe"`
`OriginalFileName`	eq	`reg.exe` corpus 43 (sigma 32, splunk 8, elastic 3)	`field:"OriginalFileName" kind:eq value:"reg.exe"`