Windows Raw Access To Master Boot Record Drive

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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.

• Type: TTP

• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

• Last Updated: 2024-05-11
• Author: Teoderick Contreras, Splunk
• ID: 7b83f666-900c-11ec-a2d9-acde48001122

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1561.002	Disk Structure Wipe	Impact

T1561

Disk Wipe

Impact

Kill Chain Phase

• Actions On Objectives

NIST

• DE.CM

CIS20

• CIS 10

CVE

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 Computer Image Device ProcessGuid ProcessId EventDescription EventCode 
| rename Computer as dest 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_raw_access_to_master_boot_record_drive_filter`

Macros

The SPL above uses the following Macros:

• security_content_ctime
• sysmon

windows_raw_access_to_master_boot_record_drive_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

• _time
• dest
• Image
• Device
• ProcessGuid
• ProcessId
• EventDescription
• EventCode

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

This event is really notable but we found minimal number of normal application from system32 folder like svchost.exe accessing it too. In this case we used 'system32' and 'syswow64' path as a filter for this detection.

Associated Analytic Story

• CISA AA22-264A
• WhisperGate
• Graceful Wipe Out Attack
• Data Destruction
• Hermetic Wiper
• Caddy Wiper
• BlackByte Ransomware
• NjRAT

RBA

Risk Score	Impact	Confidence	Message
90.0	90	100	process accessing MBR $Device$ on $dest$

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

• 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/

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

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