Detection rules › Splunk

Windows Raw Access To Master Boot Record Drive

Status
production
Severity
medium
Group by
Device, dest, dvc, process_guid, process_id, process_name, signature, signature_id, user_id, vendor_product
Author
Teoderick Contreras, Splunk
Source
github.com/splunk/security_content

The following analytic detects suspicious raw access reads to the drive containing the Master Boot Record (MBR). It leverages Sysmon EventCode 9 to identify processes attempting to read or write to the MBR sector, excluding legitimate system processes. This activity is significant because adversaries often target the MBR to wipe, encrypt, or overwrite it as part of their impact payload. If confirmed malicious, this could lead to system instability, data loss, or a complete system compromise, severely impacting the organization's operations.

Known false positives

  • There are som minimal number of normal applications from system32 folder like svchost.exe accessing the MBR. In this case we used 'system32' and 'syswow64' path as a filter for this detection.

MITRE ATT&CK coverage

Telemetry coverage

ProviderRecord / event type
SysmonEvent ID 9: RawAccessRead

Rule body

name: Windows Raw Access To Master Boot Record Drive
id: 7b83f666-900c-11ec-a2d9-acde48001122
version: 13
creation_date: '2022-02-18'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: TTP
description: The following analytic detects suspicious raw access reads to the drive containing the Master Boot Record (MBR). It leverages Sysmon EventCode 9 to identify processes attempting to read or write to the MBR sector, excluding legitimate system processes. This activity is significant because adversaries often target the MBR to wipe, encrypt, or overwrite it as part of their impact payload. If confirmed malicious, this could lead to system instability, data loss, or a complete system compromise, severely impacting the organization's operations.
data_source:
    - Sysmon EventID 9
search: '`sysmon` EventCode=9 Device = \\Device\\Harddisk0\\DR0 NOT (Image IN("*\\Windows\\System32\\*", "*\\Windows\\SysWOW64\\*")) | stats count min(_time) as firstTime max(_time) as lastTime by dest dvc process_exec process_guid process_id process_name process_path signature signature_id user_id vendor_product Device Image | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_raw_access_to_master_boot_record_drive_filter`'
how_to_implement: To successfully implement this search, you need to be ingesting logs with the raw access read event (like sysmon eventcode 9), process name and process guid from your endpoints. If you are using Sysmon, you must have at least version 6.0.4 of the Sysmon TA.
known_false_positives: There are som minimal number of normal applications from system32 folder like svchost.exe accessing the MBR. In this case we used 'system32' and 'syswow64' path as a filter for this detection.
references:
    - https://www.splunk.com/en_us/blog/security/threat-advisory-strt-ta02-destructive-software.html
    - https://www.crowdstrike.com/blog/technical-analysis-of-whispergate-malware/
    - https://www.microsoft.com/security/blog/2022/01/15/destructive-malware-targeting-ukrainian-organizations/
finding:
    title: process accessing MBR $Device$ on $dest$
    entity:
        field: dest
        type: system
        score: 50
analytic_story:
    - CISA AA22-264A
    - WhisperGate
    - Graceful Wipe Out Attack
    - Data Destruction
    - Hermetic Wiper
    - Caddy Wiper
    - BlackByte Ransomware
    - NjRAT
    - Disk Wiper
    - PathWiper
    - Void Manticore
asset_type: Endpoint
mitre_attack_id:
    - T1561.002
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint

Stages and Predicates

Stage 1: search

`sysmon` EventCode=9 Device = \\Device\\Harddisk0\\DR0 NOT (Image IN("*\\Windows\\System32\\*", "*\\Windows\\SysWOW64\\*"))

Stage 2: stats

| stats count min(_time) as firstTime max(_time) as lastTime by dest dvc process_exec process_guid process_id process_name process_path signature signature_id user_id vendor_product Device Image

Stage 3: search

| `security_content_ctime(firstTime)`

Stage 4: search

| `security_content_ctime(lastTime)`

Stage 5: search

| `windows_raw_access_to_master_boot_record_drive_filter`

Exclusions

The rule actively suppresses these predicates.

FieldKindExcluded valuesSearch
Imagein"*\\Windows\\SysWOW64\\*", "*\\Windows\\System32\\*"excludes:Image

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
Deviceeq
  • \\Device\\Harddisk0\\DR0
field:"Device" kind:eq value:"\\Device\\Harddisk0\\DR0"
EventCodeeq
  • 9 corpus 2 (splunk 2)
field:"EventID" kind:eq value:"9"